Causes of short stature

INTRODUCTION — Short stature is a term applied to a child whose height is 2 standard deviations (SD) or more below the mean for children of that sex and chronologic age (and ideally of the same racial-ethnic group). This corresponds to a height that is below the 2.3^rd percentile. Short stature may be either a variant of normal growth or caused by a disease.

The most common causes of short stature beyond the first year or two of life are familial (genetic) short stature and delayed (constitutional) growth, which are normal, nonpathologic variants of growth. The goal of the evaluation of a child with short stature is to identify the subset of children with pathologic causes (such as Turner syndrome, inflammatory bowel disease or other underlying systemic disease, or growth hormone deficiency). The evaluation also assesses the severity of the short stature and likely growth trajectory, to facilitate decisions about intervention, if appropriate.

This topic will review the main causes of short stature. The diagnostic approach to children with short stature is discussed separately. (See "Diagnostic approach to children and adolescents with short stature".)

BIOLOGY OF LINEAR GROWTH — Emerging evidence reveals that normal and pathologic variations in linear growth depend on the balance between proliferation and senescence of chondrocytes at the growth plate. This process is regulated by many systems, including:

●Endocrine mechanisms – Growth hormone, insulin-like growth factor 1 (IGF-1), androgens, and thyroid hormone all stimulate chondrogenesis, while glucocorticoids inhibit chondrogenesis. Estrogens promote linear growth by stimulating growth hormone and IGF-1 secretion, but also accelerate chondrocyte senescence, leading to fusion of the growth plates and cessation of linear growth [1].

●Proinflammatory cytokines – Some cytokines negatively regulate growth plate function. These are elevated in chronic inflammatory diseases, in which they slow linear growth and also growth plate senescence, which permits catch-up growth after the cytokine effect resolves [2,3].

●Paracrine mechanisms – Including fibroblast growth factors, bone morphogenetic proteins, parathyroid hormone-related protein, and others [4].

●Cartilage extracellular matrix – Includes collagens, proteoglycans, and other proteins.

●Intracellular pathways – Chondrocyte transcription factors including SHOX, several SOX genes, and the MAPK signaling pathway. (See 'SHOX gene variants' below.)

Together, these effects on the growth plate explain the variations in linear growth observed clinically in health and disease, including normal growth and the pubertal growth spurt, normal variation in height, and "idiopathic" short stature due to polymorphisms in these or other genes (see 'Normal variants of growth' below), and growth delay due to malnutrition, inflammatory disease, or glucocorticoid exposure (see 'Pathologic causes of short stature' below), as well as severe growth failure seen in a variety of skeletal dysplasias (see "Skeletal dysplasias: Specific disorders"). In some cases, loss-of-function variants in a gene are associated with short stature, while gain-of-function variants in the same gene are associated with tall stature [5-7].

NORMAL VARIANTS OF GROWTH — Short children with normal height velocity usually have a normal variant of growth (a nonpathologic cause of short stature), categorized as familial short stature, constitutional delay of growth and puberty, or idiopathic short stature. Normal variants of growth represent the great majority of children with short stature.

Familial short stature — Familial or genetic short stature is most often a normal variant (figure 1). A child's genetic height potential can be estimated by calculating the mid-parental height, which is based upon the heights of both biologic parents and adjusted for the sex of the child (see "Diagnostic approach to children and adolescents with short stature"). Individuals with familial short stature usually have low-normal height velocity throughout life. The otherwise normal height velocity generally distinguishes these children from those with pathologic causes of short stature. Their bone age is consistent with their chronologic age, which helps distinguish them from children with constitutional delay of growth (table 1). (See 'Constitutional delay of growth and puberty' below.)

Constitutional delay of growth and puberty — Constitutional delay of growth and puberty (CDGP; sometimes called constitutional short stature for prepubertal children) results in childhood short stature but relatively normal adult height. Children with CDGP are usually of normal size at birth. However, a downward shift in growth begins at three to six months of age that is parallel to that seen in most normally growing children in this age group but tends to be more severe and prolonged. By three or four years of age, children with CDGP usually are growing at a low-normal rate (eg, approximately 4 to 5 cm/year in preadolescent girls and 3.5 to 4.5 cm/year in preadolescent boys). The result is a growth curve that remains below, but parallel to, the third percentile for height. In addition to a low preadolescent height velocity, they tend to have delayed pubertal maturation. This leads to a marked height discrepancy during the early teenage years compared with their peers but is followed by catch-up growth when they do enter puberty (figure 2).

The hallmark of CDGP is delayed skeletal age; it is more closely related to the height age (age at which one's height would be average) than the chronologic age (table 1). For these children and adolescents, height data should be interpreted according to bone age rather than chronologic age to accurately reflect height potential. Because the bone age is delayed, growth typically continues longer than normal, often resulting in adult stature within the normal range. In many cases, there is a family history of delayed growth and puberty in one or both parents (sometimes described as being a "late bloomer"). Severe CDGP may be difficult to differentiate from growth hormone deficiency, and stimulation testing with growth hormone secretagogues may be necessary. (See "Diagnosis of growth hormone deficiency in children".)

Idiopathic short stature — A practical definition of idiopathic short stature (ISS) is a height below 2 standard deviations (SD) of the mean for age, in the absence of any endocrine, metabolic, or other diagnosis. These children have normal (often at the lower limit) height velocity and no biochemical or other evidence for a specific growth-retarding condition, which implies normal results for endocrine screening tests, including those for growth hormone deficiency. Genome-wide studies indicate that the majority of the variation in adult height is explained by several hundred genetic variations, each with a small effect [8]. However, in a small proportion of the population, short stature is caused by specific genetic variations with larger effect. As an example, emerging evidence suggests that variants in the SHOX gene (short stature homeobox) are responsible for 1 to 4 percent of individuals who would otherwise have been classified as having "idiopathic" short stature (see 'SHOX gene variants' below). In a study of 565 individuals with unexplained short stature, whole-exome sequencing was performed in 200 subjects and was able to identify a genetic cause in 21 percent of syndromic cases and in 14 percent of those with isolated short stature [9]. In addition to these genetic contributors to ISS, it appears that epigenetic changes may play a role in some children with ISS. In one study, ISS was associated with increased methylation of two promoter regions for the insulin-like growth factor 1 (IGF-1) gene; these epigenetic changes are predicted to reduce the individual's sensitivity to growth hormone [10]. (See "Growth hormone insensitivity syndromes", section on 'Defects of IGF-1 synthesis'.)

Growth hormone therapy is approved in the United States for children with ISS, which is defined for this purpose by a more stringent threshold for height (below -2.25 SD of the mean, and a predicted adult height is <63 inches [160 cm] for males and <59 inches [150 cm] for girls). Treatment indications and efficacy are discussed in detail separately. (See "Growth hormone treatment for idiopathic short stature".)

ISS is a diagnosis of exclusion. The child's height percentile is below the range predicted by the mid-parental height and the bone age is not delayed, but there is no evidence of underlying genetic, systemic, or endocrine disease [11]. By definition, these patients do not have growth hormone deficiency. Nonetheless, in many cases, the diagnosis can be made based on clinical presentation and formal testing for growth hormone deficiency is not required. If a growth hormone stimulation test is performed, children with ISS do not meet criteria for growth hormone deficiency. (See "Diagnosis of growth hormone deficiency in children", section on 'Growth hormone stimulation tests'.)

Although ISS may be a variant of normal growth, patients with this growth pattern warrant monitoring for the possibility of unrecognized underlying disease. (See 'Other causes of short stature that may be pathologic' below.)

There is ongoing controversy about the nomenclature of ISS. Here, we use the term to refer to nonfamilial cases (ie, those without patterns of familial short stature). Others consider familial short stature and CDGP to be subcategories of ISS [11,12].

Small for gestational age infants with catch-up growth — Most infants born small for gestational age (SGA) experience catch-up growth by two years of age, sufficient to be within the normal range (length above -2 SD, ie, >2.3^rd percentile). (See "Infants with fetal (intrauterine) growth restriction".)

Approximately 10 percent of SGA infants, particularly those born with more severe SGA, do not experience catch-up growth to reach the normal range by two years of age. This group of SGA infants can be considered to have a pathologic pattern of growth, so they are discussed later in this topic review. (See 'Other causes of short stature that may be pathologic' below.)

PATHOLOGIC CAUSES OF SHORT STATURE — The hallmark of most pathologic causes of short stature is low height velocity.

Systemic disorders or processes with secondary effects on growth — Almost any serious disease can cause growth failure (table 2). The abnormalities of growth and maturation that occur in children with acute or chronic illnesses may result from the primary disease process because of increased energy needs or nutritional deprivation (eg, decreased intake or malabsorption). Growth also may be affected by treatments, such as radiation therapy (a permanent effect), glucocorticoids, stimulants used for attention deficit hyperactivity disorder, or chemotherapy (mostly transient effects but may have a small permanent effect if treatment is prolonged [13-16]). Some diseases may cause secondary derangements of the hormones that affect growth.

Diseases or processes that are particularly important causes of growth failure are outlined below. Other disorders that can cause growth failure with weight loss are outlined in a separate topic review. (See "Evaluation of weight loss in infants over six months of age, children, and adolescents", section on 'Differential diagnosis'.)

Undernutrition — Undernutrition is the most common cause of poor growth globally. In many cases, undernutrition is isolated, caused by inadequate food supply (eg, due to poverty [17]) or self-imposed restriction (eg, due to fear of obesity [18]). In other cases, undernutrition is related to an underlying systemic disease that interferes with food intake or absorption or increases energy needs.

Insufficient nutrition tends to lead to short stature with a delayed pattern of growth; the hallmark is low weight-for-height.

Glucocorticoid therapy — Since glucocorticoids are used for treatment of a variety of diseases, they are a common cause of growth faltering in children. The growth failure can develop with or without other symptoms of glucocorticoid excess, known as Cushing syndrome (see 'Cushing syndrome' below). They suppress growth through several different mechanisms, including interference with endogenous growth hormone secretion and action, bone formation, nitrogen retention, and collagen formation [19]. The growth effects of glucocorticoids are related to the type, dose, and duration of the exposure. If glucocorticoids are discontinued, children usually experience some catch-up growth.

Growth impairment is more pronounced with agents with a longer duration of action (eg, dexamethasone > prednisone > hydrocortisone). It is most pronounced when glucocorticoids are administered daily as compared with an alternate-day regimen [19]. Some inhibition of linear growth occurs even at the doses that are used for physiologic replacement (ie, prednisone doses of 3 to 5 mg/m² per day; approximately 0.075 to 0.125 mg/kg per day), and progressive growth impairment occurs with increasing doses [20]. As an example, in a large series of children with growth failure due to chronic treatment with glucocorticoids for a systemic disease, the mean prednisone-equivalent dose was 0.5±0.6 mg/kg per day [20]. Growth impairment can even occur with prolonged administration of inhaled glucocorticoids during childhood, although the overall effect of these agents on adult height appears to be small [21,22]. (See "Pharmacologic use of glucocorticoids" and "Major side effects of inhaled glucocorticoids", section on 'Growth deceleration'.)

Prolonged treatment with systemic glucocorticoids may have persistent effects on growth after therapy is discontinued. In a study of 224 children with cystic fibrosis who previously had been treated for up to four years with either alternate-day prednisone or placebo, mean height after age 18 years (on average six to seven years after cessation of therapy) was significantly lower in boys who had received either high- or low-dose prednisone (170.5 and 170.7 versus 174.6 cm with placebo; p = 0.03) [23]. This effect was most pronounced in boys who had started taking prednisone at six to eight years of age. In contrast, there was no persistent growth impairment in girls treated similarly.

Gastrointestinal disease — Children with growth failure resulting from gastrointestinal disease tend to have a greater deficit in weight than height (ie, they are underweight-for-height) in contrast to those with endocrine disorders, who are often overweight-for-height (see below).

Approximately 30 percent of children with Crohn disease have a decrease in height velocity before the onset of gastrointestinal symptoms [24], and approximately 10 percent of children with Crohn disease have short stature when the Crohn disease is diagnosed [25,26]. The growth failure is closely related to the inflammatory disease process (mediated by proinflammatory cytokines), as well as decreased food intake, malabsorption, and/or high-dose glucocorticoids if used for treatment (see "Growth failure and pubertal delay in children with inflammatory bowel disease"). Similarly, celiac disease can present with growth failure, especially in younger children [27]. Both of these disorders are important considerations in the evaluation of a child whose linear growth has slowed, particularly if there are gastrointestinal symptoms and/or slow weight gain. (See "Epidemiology, pathogenesis, and clinical manifestations of celiac disease in children".)

Rheumatologic disease — Childhood rheumatologic diseases, especially systemic juvenile idiopathic arthritis, are frequently associated with growth retardation [28]. This may be a consequence of the proinflammatory cytokines associated with disease activity and is also caused by the high-dose glucocorticoids that are often used for treatment [29,30]. Common presenting symptoms in juvenile idiopathic arthritis are fever, arthralgias, rash, and lymphadenopathy, in addition to growth faltering. (See "Systemic juvenile idiopathic arthritis: Course, prognosis, and complications", section on 'Growth retardation'.)

Chronic kidney disease — Growth failure is seen in at least one-third of children with chronic kidney disease. The primary causes of growth faltering in children with chronic kidney disease are disturbances of growth hormone metabolism and its main mediator, insulin-like growth factor 1 (IGF-1). Other factors may include metabolic acidosis, uremia, poor nutrition secondary to dietary restrictions, anorexia of chronic illness, anemia, calcium and phosphorus imbalance, renal osteodystrophy, or use of high-dose glucocorticoids. Affected patients are candidates for growth hormone therapy until renal transplantation, and some of these patients may also benefit from growth hormone therapy after transplantation. (See "Growth failure in children with chronic kidney disease: Risk factors, evaluation, and diagnosis" and "Growth failure in children with chronic kidney disease: Treatment with growth hormone".)

Metabolic acidosis alone can also impair growth, as occurs in children with renal tubular acidosis [31]. Alkali therapy may lead to attainment and maintenance of normal growth and adult stature [31]. (See "Etiology and clinical manifestations of renal tubular acidosis in infants and children".)

Cancer — Children with cancer may grow poorly before diagnosis because of poor food intake, nausea, vomiting, and increased caloric utilization. After diagnosis, anorexia, nausea, and vomiting induced by chemotherapy and radiotherapy also can contribute to impaired growth. These effects often subside within one to two years of initiating treatment, and some children then have catch-up growth [32,33].

Late growth failure is common in children who received cranial radiotherapy because it can damage the hypothalamus and cause insufficiency of one or more hormones from the pituitary, including growth hormone, gonadotropins, and thyroid-stimulating hormone (TSH) [34-38]. In younger children, especially girls, cranial radiotherapy can cause precocious puberty and adult short stature. Primary hypothyroidism also can occur if the thyroid gland was in the radiation field. Spinal irradiation may result in slow growth of the spine with relative preservation of normal limb growth. (See "Bone problems in childhood cancer patients", section on 'Altered epiphyseal growth'.)

Pulmonary disease — Cystic fibrosis is predominantly a pulmonary and gastrointestinal disease. Growth failure in children with this disorder may be caused by multiple mechanisms, including poor food intake, maldigestion or malabsorption, chronic infection, and increased energy requirements (work of breathing) [39]. This "natural history" of cystic fibrosis is likely to change with the increasing use of cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy, which has substantial benefits for pulmonary disease and also improves growth and nutrition [40]. (See "Cystic fibrosis: Nutritional issues" and "Cystic fibrosis: Overview of the treatment of lung disease".)

Immune deficiencies also may present with pulmonary symptoms and/or growth failure. (See "Bronchiectasis in children: Pathophysiology and causes".)

Asthma has been associated with a diminished height velocity, which is most pronounced with severe disease. Growth failure in children with asthma is usually due to treatment with glucocorticoids, including inhaled glucocorticoids. (See 'Glucocorticoid therapy' above.)

Cardiac disease — Growth failure is common in children with severe heart disease of any cause. The major pathogenetic factors are thought to be hypoxia, anorexia, and increased basal energy requirements [41]. Occasionally, growth failure is the presenting feature of the heart disease. (See "Suspected heart disease in infants and children: Criteria for referral".)

Immunologic disease — Human immunodeficiency virus (HIV) infection is associated with growth failure. Mechanisms include anorexia, malabsorption, diarrhea, severe infections, and failure of one or more major organ systems [42]. (See "Pediatric HIV infection: Classification, clinical manifestations, and outcome", section on 'Wasting syndrome'.)

Growth failure also can occur with other immunologic deficiencies such as common variable immunodeficiency or severe combined immunodeficiency syndrome. As with HIV infection, multiple factors are probably involved. (See "Common variable immunodeficiency in children" and "Severe combined immunodeficiency (SCID): An overview".)

Metabolic diseases — Growth failure is common in children and adolescents with many of the inborn disorders of metabolism. Among acquired metabolic diseases, the most common is type 1 diabetes mellitus. In the past, type 1 diabetes mellitus was an important cause of short stature and attenuated growth because of caloric deficit resulting from severe glucosuria [43]. However, it is now rare because of improvements in therapy. Children with type 1 diabetes have some decrease in IGF-1 production or action, and there is a negative correlation between hemoglobin A1c percent (as an index of metabolic control) and adult height [44,45]. Nonetheless, in children with fair to good metabolic control, growth and adult height are usually within normal ranges. Occasionally, children with diabetes and very poor glycemic control develop Mauriac syndrome, characterized by attenuated linear growth, and delayed puberty, hepatomegaly, and Cushingoid features. (See "Complications and screening in children and adolescents with type 1 diabetes mellitus", section on 'Growth'.)

Any disorder associated with vitamin D deficiency or decreased vitamin D action can cause hypophosphatemia and rickets; rickets is characterized by abnormal epiphyseal development, bowing of the extremities, and diminished growth. Vitamin D deficiency in the absence of rickets does not seem to affect linear growth. (See "Overview of rickets in children" and "Hereditary hypophosphatemic rickets and tumor-induced osteomalacia".)

Endocrine causes of short stature — Primary endocrine disorders with effects on growth are uncommon but are important to identify because they can be treated (table 2). In general, these disorders are characterized by excessive weight for height. They should be considered in any child with markedly reduced height velocity, and especially in those with other pituitary disorders, brain tumors, optic nerve hypoplasia (also known as septo-optic dysplasia), midline brain and facial defects, neonatal hypoglycemia, history of cranial irradiation, or a familial pattern of growth hormone deficiency [46]. Any patient with an abnormality of one pituitary hormone (central hypothyroidism, Cushing disease, or growth hormone deficiency) should be evaluated for other pituitary hormone deficiencies.

Hypothyroidism — Growth failure is a well-recognized consequence of hypothyroidism during childhood and may be the presenting feature. The bone age is delayed; as a result, many children with hypothyroidism have a reasonably normal growth potential once the disorder is identified and treated. Children whose hypothyroidism is promptly diagnosed and treated often have good catch-up growth and normal adult height outcomes, unless they have other causes for short stature. The evaluation should include measurements of both TSH and free thyroxine to allow detection of both primary and central hypothyroidism.

Growth hormone deficiency

●Congenital – If growth hormone deficiency is congenital and severe, the diagnosis is relatively easy to confirm. Affected children present with pronounced postnatal growth failure, delayed bone age, and very low serum concentrations of growth hormone, IGF-1, and IGF-binding protein-3 (IGFBP-3; the major circulating binding protein for IGF-1) [46]. Additional findings are hypoglycemia, prolonged conjugated hyperbilirubinemia, midface hypoplasia, hypotonia, high-pitched voice, truncal adiposity, and micropenis in boys, especially if gonadotropins are deficient as well.

The degree of postnatal growth failure varies. The decision to undertake stimulation testing of growth hormone should be based on strict auxologic criteria. (See "Diagnosis of growth hormone deficiency in children".)

In some patients, only growth hormone is deficient (known as "isolated" growth hormone deficiency), which may be caused by one of several specific genetic disorders. In other patients, the growth hormone deficiency is or can later be associated with other pituitary hormone deficiencies, including ACTH, TSH, gonadotropins, and/or, rarely, antidiuretic hormone. The clinical manifestations depend on the type and severity of the pituitary hormone deficiencies. Multiple pituitary hormone defects may be related to structural central nervous system abnormalities or specific genetic disorders. (See "Diagnosis of growth hormone deficiency in children", section on 'Molecular genetics of growth hormone deficiency'.)

●Acquired – Causes of acquired growth hormone deficiency include intracranial tumor (eg, craniopharyngioma), cranial irradiation, and head trauma.

Sexual precocity — Several conditions are associated with increased secretion of gonadal steroids (estradiol in girls and testosterone in boys), which have two consequences. One is sexual precocity. The other is accelerated epiphyseal maturation, which causes rapid childhood growth but more rapid advancement of bone age. Without intervention, these initially tall children will be short adults because early epiphyseal closure stops linear growth prematurely.

There are two types of sexual precocity:

●Central precocious puberty, also known as gonadotropin-dependent precocious puberty, refers to the early occurrence of normal puberty. Precocious puberty historically had been defined as sexual maturation in girls before the age of eight years and in boys before the age of nine years; however, data for girls, particularly Black girls, indicate that the age of onset of normal puberty is younger [47-49]. The hallmarks of central precocious puberty are accelerated growth and advanced bone age, plus breast development in girls and testicular enlargement in boys [50]. The pattern of secretion of pituitary gonadotropins and gonadal sex steroids is normal but early. (See "Definition, etiology, and evaluation of precocious puberty", section on 'Causes of central precocious puberty'.)

●Peripheral precocious puberty, also known as gonadotropin-independent precocious puberty, refers to sexual precocity not mediated by activation of the hypothalamic-pituitary-gonadal axis. Causes include: adrenal or gonadal disorders, human chorionic gonadotropin-producing tumors, longstanding untreated hypothyroidism, McCune-Albright syndrome, testotoxicosis, and exposure to exogenous sex steroids. The clinical manifestations are similar to those of central precocious puberty, except that the sexual maturation may be that of the opposite sex, eg, androgenic effects in girls with congenital adrenal hyperplasia. For boys, there is no testicular enlargement with peripheral precocious puberty. (See "Definition, etiology, and evaluation of precocious puberty", section on 'Causes of peripheral precocity'.)

Cushing syndrome — Cushing syndrome is caused by excessive glucocorticoids and is characterized by the combination of weight gain and growth retardation, resulting in excessive weight-for-height (figure 3) [51-53].

Endogenous Cushing syndrome (caused by excessive endogenous production of cortisol) is rare in children. The most common cause is a corticotropin (ACTH)-secreting pituitary adenoma (Cushing disease) [51,53,54]. The syndrome also may be caused by an adrenal adenoma, especially in younger children. In one series of children with endogenous Cushing syndrome, growth retardation was common (83 percent), but most patients had bone age within normal limits at diagnosis [51]. Other key clinical features are central obesity, suprascapular fat pad ("buffalo hump"), abdominal striae, hirsutism, acne, and neuropsychological symptoms [53]. The best tests to establish the diagnosis are a 24-hour urine collection for free cortisol (and creatinine), or a dexamethasone suppression test. Measurements of serum cortisol are not reliable screening tests, unless performed late at night. (See "Epidemiology and clinical manifestations of Cushing syndrome" and "Establishing the diagnosis of Cushing syndrome".)

Exogenous sources of glucocorticoids (eg, due to glucocorticoid therapy for asthma or inflammatory bowel disease) are a much more common cause of Cushing syndrome. (See 'Glucocorticoid therapy' above.)

Pseudohypoparathyroidism — Type 1 pseudohypoparathyroidism is characterized by physical findings that may include brachydactyly, short stature, stocky build, early-onset obesity, ectopic ossifications, and, sometimes, neurodevelopmental deficits as well as resistance to parathyroid hormone. (See "Etiology of hypocalcemia in infants and children", section on 'Type 1 PHP'.)

Genetic diseases with primary effects on growth — Several genetic disorders have prominent effects on growth. These occasionally present with short stature as the initial clinical manifestation. Many other genetic disorders, such as Down syndrome, include short stature but are not listed here, because stature is not a primary identifying characteristic.

Turner syndrome — Turner syndrome is an important consideration in girls with short stature, and especially growth failure, because shortness may be the presenting feature of the syndrome; other physical abnormalities are variably expressed (table 3). Virtually all girls with Turner syndrome have short stature, with an average adult height approximately 20 cm shorter than predicted by the mid-parental height. In addition, affected patients usually have absent or very delayed pubertal maturation and may have a square "shield" chest, webbed neck, cubitus valgus (increased carrying angle of the arm), genu valgum (inward-tilting knees), shortened fourth metacarpals, and Madelung deformity of the forearm (picture 1 and image 1). A Madelung deformity is a growth disturbance in the distal radial epiphysis that results in volar- and ulnar-tilted distal radial articular surface, volar translation of the hand and wrist, and a dorsally prominent distal ulna and wrist pain; this condition is sometimes termed "bayonet wrist." Prompt diagnosis of Turner Syndrome is important because of associated cardiovascular, renal, and endocrine abnormalities, which may require treatment, including growth hormone therapy. (See "Clinical manifestations and diagnosis of Turner syndrome".)

SHOX gene variants — Variants in the SHOX (short stature homeobox)-containing gene on the X chromosome cause a syndrome in which the primary manifestation is short stature, which tends to be more severe in girls (MIM #300582). In addition to short stature, individuals with this variant tend to have shorter forearms and lower legs (with reductions in arm span and leg length compared with trunk), Madelung deformity of the forearm (focal dysplasia of the distal radial physis) (picture 1 and image 1), cubitus valgus (increased carrying angle of the arm), high-arched palate, and muscular hypertrophy (reflected as a short, stocky appearance), compared with those with idiopathic short stature (ISS) but no SHOX variant [55]. These skeletal abnormalities are similar to those seen in many patients with Turner syndrome. (See "Sex chromosome abnormalities", section on 'Xp22 SHOX deletions'.)

SHOX variants are present in approximately 1 to 4 percent of patients who would otherwise have been classified as having "idiopathic" short stature [55-57]. The SHOX gene is found in the pseudoautosomal region of both the X and Y chromosomes and is responsible for the short stature and skeletal deformities associated with Turner syndrome, Leri-Weill dyschondrosteosis, and Langer mesomelic dysplasia [56,58-61] (see "Skeletal dysplasias: Specific disorders", section on 'Leri-Weill dyschondrosteosis'). Growth hormone treatment is effective in increasing linear growth in patients with isolated SHOX deficiency [62-64]. (See "Growth hormone treatment for idiopathic short stature".)

Prader-Willi syndrome — Prader-Willi syndrome (MIM #176270) is the most common syndromic form of obesity. Obesity and hyperphagia typically develop during early childhood and can be severe. Other common clinical characteristics are hypotonia and feeding problems during infancy, developmental delay, and hypogonadism. Short stature is common but may not develop until late childhood when the child fails to undergo a pubertal growth spurt. Treatment with growth hormone increases linear growth and improves body composition. (See "Prader-Willi syndrome: Management".)

Noonan syndrome — Noonan syndrome (MIM #163950) is a relatively common autosomal dominant disorder that is associated with short stature and congenital heart disease, most often pulmonic stenosis. It is clinically and genetically heterogeneous and can present at any age. The most consistent clinical features are widely spaced eyes (hypertelorism) and low-set ears (>80 percent), short stature (>70 percent), and pulmonic stenosis (approximately 50 percent) [65]. Children with Noonan syndrome may present with short stature, a murmur indicating congenital heart disease, or delayed speech or motor milestones. Short stature associated with Noonan syndrome can be treated effectively with growth hormone. This disorder is discussed in detail in a separate topic review. (See "Noonan syndrome".)

Silver-Russell syndrome — Silver-Russell syndrome (MIM #180860, also known as Russell-Silver syndrome) is characterized by severe intrauterine growth restriction and postnatal growth retardation with a prominent forehead, triangular face, downturned corners of the mouth, and body asymmetry (hemihypertrophy) [66,67]. The facial features tend to become less obvious with age. The majority of infants have feeding difficulties, mild developmental delay that occurs in approximately one-third of subjects, and sleep-disordered breathing [68-70]. In approximately 60 percent of subjects, the syndrome is associated with epigenetic alterations involving either hypomethylation of an imprinting control region that regulates expression of the insulin-like growth factor 2 gene (IGF2) or others on chromosome 11p15.5. IGF-2 has important effects on growth, especially during fetal development. Approximately 10 percent of cases are caused by maternal uniparental disomy of chromosome 7 [71]. Accordingly, one study describes severe pre- and postnatal growth restriction in four members of the same family with clinical features of Silver-Russell syndrome, due to a paternally inherited variant in IGF2 [72].

A few reports suggest modest efficacy of growth hormone treatment of individuals with Silver-Russell syndrome [73-77]. In one study, the mean adult height was -1.3 standard deviations (SD) when growth hormone was started at a young age [73], compared with an adult height of -4.2 to -2.9 SD in untreated subjects with this disorder [73,77,78]. In a separate study, mean adult height in growth hormone-treated subjects was -2.17 SD, despite a mean total height gain of 1.3 SD [79]. Of note, individuals with the hypomethylation defect tend to have inappropriately high levels of IGF-1 and IGFBP-3, suggesting a reduced sensitivity to IGF-1 [68,80].

Skeletal dysplasias/growth plate abnormalities — Skeletal dysplasias associated with short stature are caused by inherited defects in cartilage/bone development and are often associated with disproportionate short stature (with limbs disproportionately short for the trunk or vice versa). Some present prenatally and are detected on prenatal ultrasound, whereas others present during childhood with short stature. These disorders should be suspected in a child presenting with short stature and bone deformities, recurrent fractures, or abnormal findings on radiographs (eg, enchondromas, bowing or shortening of the long bones, vertebral defects, or rib abnormalities).

There are a variety of skeletal dysplasias, with very variable phenotypes, including achondroplasia, hypochondroplasia, spondyloepiphyseal dysplasia, osteopetrosis, and osteogenesis imperfecta. In one study, subtle skeletal dysplasias were found in 18.5 percent of patients previously labeled as either ISS or having been born SGA [81]. The most common forms were dyschondrosteosis (due to SHOX variants in 61.5 percent of those undergoing genetic testing) and hypochondroplasia (due to FGFR3 [fibroblast growth factor receptor 3] variants in 25 percent of those subjects undergoing genetic testing). These disorders were especially prevalent among those with parents who are also very short. (See "Skeletal dysplasias: Specific disorders" and "Skeletal dysplasias: Approach to evaluation" and "Achondroplasia".)

Many genes participate in growth plate development, including SHOX (as discussed above), FGFR3, ACAN, NPR2, IHH, and FBN1 and PTPN11. Variants in these genes have been associated with distinct degrees of short stature with or without other mild features, such as slightly disproportionate growth and nonspecific skeletal abnormalities (eg, brachydactyly, short thumb, or midface hypoplasia) [82,83].

●Autosomal dominant variants in FGFR3 cause achondroplasia and related chondrodysplasia syndromes, including hypochondroplasia and thanatophoric dysplasia [84]. (See "Skeletal dysplasias: Specific disorders", section on 'Achondroplasia and hypochondroplasia'.)

●ACAN encodes a proteoglycan present in the extracellular matrix; it has a primordial structure and functional role in the growth plate cartilage. Variants in ACAN result in a broad phenotypic spectrum of autosomal dominant mild and proportionate short stature with advanced bone age (average adult height -3.0 SD) that is frequently associated with early-onset osteoarthritis and intervertebral disc disease [83].

●Homozygous defects in NPR2 cause a severe skeletal dysplasia, characterized by severe short stature, phalangeal-metacarpal abnormalities, and shortening and bowing of the limbs. Heterozygous NPR2 variants have been described in children with ISS [85,86].

●Variants in IHH are reported to cause brachydactyly type A1 and acrocapitofemoral dysplasia [87].

●FBN1 variants are reported in patients with acromelic dysplasia syndromes, consisting of severe short stature, short hands and feet, and skin thickening [88].

Conversely, other mutations in the NPR2 or FBN1 genes are associated with tall stature (Miura type of epiphyseal chondrodysplasia and Marfan syndrome, respectively). (See "The child with tall stature and/or abnormally rapid growth", section on 'Biology of linear growth'.)

Other causes of short stature that may be pathologic

●Idiopathic short stature – Some individuals with apparent ISS may have underlying disorders that are pathologic but not diagnosed during a standard evaluation. If the short stature is severe, these patients warrant a detailed evaluation and ongoing monitoring for the possibility of subclinical underlying systemic disease. As genetic testing becomes more widely available and cost-effective, it will be increasingly used to identify genetic causes of short stature in a significant proportion of these children. Some of these children may also be candidates for growth hormone therapy. (See 'Idiopathic short stature' above and "Diagnostic approach to children and adolescents with short stature", section on 'Laboratory and imaging studies' and "Growth hormone treatment for idiopathic short stature".)

●Small for gestational age – Approximately 10 percent of infants born SGA fail to experience catch-up growth sufficient to be within the normal range by two years of age. This growth pattern is more likely in those with severe SGA and can be considered pathologic, although the underlying mechanisms are unclear and likely vary. Multigene sequencing analysis of SGA children with isolated short stature may be able to identify a pathogenic or likely pathogenic genetic variant in 15 percent of patients [89]. Children with persistent short stature after ages two to four years may benefit from growth hormone therapy. (See "Growth hormone treatment for children born small for gestational age".)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Turner syndrome" and "Society guideline links: Growth hormone deficiency and other growth disorders".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topic (see "Patient education: My child is short (The Basics)")

SUMMARY

●Definition – Short stature is defined as height that is 2 standard deviations (SD) or more below the mean height for children of that sex and chronologic age in a given population. This translates to a height that is below the 2.3^rd percentile. (See 'Introduction' above.)

●Normal variants of growth – The two most common causes of short stature are familial (genetic) short stature and constitutional delay of growth and puberty (CDGP), which are normal variants of growth. These growth patterns often can be distinguished from one another, but some children have features of both (table 1). Another variant is idiopathic short stature, which is characterized by normal or near-normal height velocity and no evidence for a specific growth-retarding condition. (See 'Normal variants of growth' above.)

●Pathologic causes of short stature – Pathologic causes of short stature include (table 2):

•Systemic disorders – Almost any serious systemic disease can cause growth failure. Systemic disorders or processes that may present with growth failure and/or delayed puberty include undernutrition, glucocorticoid therapy, gastrointestinal disease (especially Crohn disease and celiac disease), and renal disease. (See 'Systemic disorders or processes with secondary effects on growth' above.)

•Endocrine causes of short stature – Endocrine causes of short stature include hypothyroidism, growth hormone deficiency, sexual precocity, Cushing syndrome, and pseudohypoparathyroidism type 1. (See 'Endocrine causes of short stature' above.)

•Genetic causes of short stature – A variety of genetic syndromes and congenital malformations are associated with short stature, including Turner, Prader-Willi, Noonan, Silver-Russell and Down syndromes and SHOX gene variants. Turner syndrome is particularly important because short stature and/or absent pubertal maturation may be the presenting feature, with or without other characteristic clinical features (table 3). (See 'Turner syndrome' above and 'Genetic diseases with primary effects on growth' above.)

Skeletal dysplasias/growth plate abnormalities are often associated with disproportionate short stature, including achondroplasia, hypochondroplasia, spondylodysplasia, osteopetrosis, and osteogenesis imperfecta. (See 'Skeletal dysplasias/growth plate abnormalities' above and "Skeletal dysplasias: Specific disorders".)