Congenital hypothyroidism or other causes of low total T4 at birth, with thyroid function test results

Cause	Incidence	Serum free T4	Serum T4	Serum TSH
Primary hypothyroidism	1:2000 to 1:4000	↓	↓	↑
Thyroid dysgenesis – Ectopia, aplasia, or hypoplasia		↓	↓	↑
Resistance to TSH*		Normal or ↓	Normal or ↓	↑
Inborn errors of thyroxine synthesis (dyshormonogenesis)		↓	↓	↑
Gland in situ^¶		↓	↓	↑
Defects in thyroid hormone transport (THCMTD)^Δ	Rare	↓	↓	Normal or slightly ↑
Defects in thyroid hormone action – Resistance to thyroid hormone	1:40,000	↑	↑	Normal or slightly ↑
Central hypothyroidism	1:16,404 to 1:29,000	↓	↓	Normal or ↓
Transient hypothyroidism
Iodine deficiency (worldwide, in areas of endemic iodine deficiency)		↓	↓	↑
Iodide excess (from topical iodine antiseptics, natural supplements, drugs, or contrast agents)		↓	↓	↑
Maternal antibody-mediated hypothyroidism	1:180,000	↓	↓	↑
Gland in situ^¶		↓	↓	↑
TBG deficiency (causes low serum total T4 concentrations^◊ but not hypothyroidism)	1:4000 to 1:8000	Normal	↓	Normal

T4: thyroxine; TSH: thyroid-stimulating hormone (thyrotropin); THCMTD: thyroid hormone cell membrane transport defect; TBG: thyroxine-binding globulin; T3: triiodothyronine.

* Resistance to TSH is usually due to a mutation in the TSH receptor.

¶ Gland in situ refers to a normal-sized or large thyroid gland in a normal location. In modern studies, this is the most common category of congenital hypothyroidism. While the underlying cause is often unknown, it likely represents a mild form of thyroid dyshormonogenesis. On follow-up, approximately one-half of thyroid gland in situ cases have transient hypothyroidism.

Δ THCMTD is characterized by high serum T3 and low reverse T3 concentrations.

◊ TBG deficiency is characterized by low serum total T4 but normal serum free T4 concentrations.

Graphic 68356 Version 15.0

خرید پکیج

Congenital hypothyroidism or other causes of low total T4 at birth, with thyroid function test results