Micropenis.

Abstract

Micropenis, i.e., a structurally normal but abnormally small penis is defined as stretched penile length (SPL) 2.5 SD below the mean for age and sexual stage. Several studies worldwide have published country-specific normative data on SPL; an appropriate cutoff for evaluation of micropenis as per international standards would be below 2cm at birth and below 4cm after 5 y of age. Testosterone production by fetal testes, its conversion to dihydrotestosterone (DHT) and its action on the androgen receptor is necessary for normal penile development. Hypothalamo-pituitary disorders (gonadotropin or growth hormone deficiencies), genetic syndromes, partial gonadal dysgenesis, testicular regression, disorders of testosterone biosynthesis and action constitute the various etiologies of micropenis. Associated hypospadias, incomplete scrotal fusion, and cryptorchidism are suggestive of disorders of sex development (DSD). Along with basal and human chorionic gonadotropins (HCG)-stimulated gonadotropins, testosterone, DHT, and androstenedione levels, karyotype assessment is equally important. Treatment aims at attaining penile length sufficient enough for urination and to perform sexual function. Hormonal therapy with intramuscular or topical testosterone, topical DHT or recombinant follicle stimulating hormone (FSH) and luteinizing hormone (LH) should be attempted in the neonatal or infancy period. The role of surgery for micropenis is limited and has variable patient satisfaction and complication outcomes. There is a need for long-term studies on the adult SPL achieved following treatment for micropenis in infancy and childhood.