Medical Care
Testosterone therapy in the form of 3 monthly intramuscular (IM) injections has been used to increase penis size in infants and children.
Testosterone therapy has generally been found effective in treating micropenis due to testosterone deficiency. In 1999, Bin-Abbas et al showed that 1 or 2 courses of 3 testosterone injections (25-50 mg) administered at 4-week intervals in infancy or childhood resulted in sufficient increase in penis sizes to reach the reference range for age. [3] With appropriate pubertal and adult replacement, patients achieved normal adult penis size and reported sexual activity and appropriate gender identity. [3] Thus, evidence suggests that treatment with testosterone during infancy or childhood primes the penis for later growth during puberty.
Infants with other hormonal deficiencies (growth hormone deficiency, hypothyroidism, adrenal insufficiency) should receive appropriate hormonal replacements.
A study by Becker et al of three related 46,XY males with PAIS found mixed results from the treatment of micropenis with topical dihydrotestosterone (4-month course of daily gel application). In the prepubertal patient, stretched penile length (SPL) increased from 2.5 cm to 3.5 cm, while in the peripubertal patient, it increased from 3.5 cm to 5.7 cm. However, an adult patient who had already undergone 1 year of weekly, high-dose testosterone treatment demonstrated no additional increase in SPL following topical therapy. [36]
A study by Xu et al supported the efficacy of short-term, low-dose, percutaneous dihydrotestosterone administration in the treatment of children with micropenis. Average stretched penile lengths in the study increased from 1.68 cm before treatment to 2.2, 2.6, and 2.9 cm following 1, 3, and 6 months of therapy, respectively. In 14 out of 23 cases (61%), standard penile length range was achieved. However, despite a lack of significant side effects in the study, aside from elevated serum dihydrotestosterone levels, the investigators urged caution in the use of this treatment, since long-term studies and determination of ideal dosage are still needed. [37]
A study by Stoupa et al of six infants with micropenis—due to isolated congenital hypogonadotropic hypogonadism (CHH; 4 patients), panhypopituitarism (1 patient), or PAIS (1 patient)—indicated that early postnatal infusion of gonadotropins is a safe and effective therapy. Micropenis resolved in all but one patient, with the stretched penile length in the CHH patients increasing from an initial 13.8 mm to 42.6 mm and in the PAIS patient from an initial 13 mm to 38 mm. [38]
A literature review by Krishnan et al indicated that in males with hypospadias, preoperative testosterone therapy can increase penile length and circumference, providing adequate tissue in patients with microphallus for successful urethral reconstruction. Evidence suggested that in patients undergoing the repair operation, preoperative testosterone treatment leads to fewer complications and improved cosmesis. The investigators added, however, that no consensus exists as to whether the testosterone would better be administered topically or parenterally. [39]
A study of 10 patients by Papadimitriou et al indicated that in infants with congenital hypogonadotropic hypogonadism, daily subcutaneous injections of luteinizing hormone/follicle-stimulating hormone (LH/FSH) (75/150 IU) for 3 months can successfully treat micropenis and cryptorchidism, with the regimen producing a mimicking of male minipuberty. While the pretreatment levels of LH and FSH were undetectable, LH attained a high-normal posttreatment level of 4.45 IU/L, and FSH, a supranormal level of 83 IU/L. Median anti-Müllerian hormone, inhibin B, and testosterone levels increased to normal, and stretched penile length, with a pretreatment median of 2 cm, increased to 3.8 cm. By the end of the third month, all patients had descended testes. [40]
Surgical Care
Gender reassignment with appropriate genitoplasty has been performed. Because most boys with micropenis and descended testes are sensitive to testosterone therapy, consider genitoplasty only in extreme situations in which testosterone insensitivity is demonstrated. Even then, some authors question the wisdom of gender reassignment. [9, 10]
Circumcision should be avoided, or at least delayed, until appropriate evaluation, gender assignment, and therapy are completed. If associated with penile growth, testosterone therapy may facilitate the circumcision (see Medical Care).
Consultations
As soon as an infant is discovered to have micropenis, a pediatric endocrinologist should be consulted. In some cases, the involvement of a pediatric urologist can also be helpful. Psychological support and social services assistance may be useful.
