The most common morbidities in Klinefelter syndrome

Morbidity	Frequency (%)	Comments
Children
Learning disability	>75
Delayed speech development	>40
Autism spectrum disorder	30 to 50	Most patients are diagnosed as children
Psychiatric disorder	>25	Anxiety and depressed mood are most common
Decreased penis size	10 to 25	May not meet strict criteria for micropenis
Cryptorchidism	25 to 40	Cryptorchidism is typically detected during childhood
Adults
Testosterone deficiency and infertility with azoospermia and small testes	99 to 100	A few males with Klinefelter syndrome (particularly mosaic Klinefelter syndrome) have normal serum testosterone concentrations and sperm in the ejaculate at time of diagnosis
Metabolic syndrome	40 to 50	Prevalence increases with age
Type 2 diabetes mellitus	10 to 40	Prevalence increases with age
Osteoporosis	40	Prevalence increases with age
Tremor	>25	Prevalence increases with age
Psychiatric disorder	>25	Anxiety and depressed mood are most common

Courtesy of Bradley D Anawalt, MD and Alvin M Matsumoto, MD.

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