PENILE HEMODYNAMICS IN HYPOGONADAL MEN WITH MICROPENIS PINAR KADIOG ˘ LU, AHMET TEFEKLI, BU ¨ LENT EROL, O ¨ NER S ¸ ANLI, MUAMMER KENDIRCI, ES ¸REF O ¨ ZER, U ¨ STU ¨ N KORUGAN, AND ATES ¸ KADIOG ˘ LU ABSTRACT Objectives. To document the penile vascular and erectile response to intracavernous injection (ICI) of vasoactive agent in hypogonadal men with micropenis. Methods. A total of 15, previously untreated, hypogonadal men with micropenis (stretched penis length less than 2.5 SD below the mean of the normal population) underwent a detailed urologic and endocrinologic evaluation. Their mean age was 21.2  4.2 years. Penile hemodynamics were assessed by color Doppler ultrasonography before and after ICI of 5 g of prostaglandin E 1 combined with manual genital self- stimulation. Results. Endocrinologic evaluation revealed that hypogonadism was hypogonadotropic in 10 (66.7%) and hypergonadotropic in 5 (33.3%). Karyotype analysis showed 46XY in all. Their mean stretched penile length was 6.2  1.4 cm (range 3 to 7.5) and increased to a mean of 6.96  1.5 cm (range 4 to 8.5) after ICI. The serum free testosterone levels ranged from 0.2 to 3.2 pg/mL (mean 1.9  0.92). None had had any previous sexual experience, and 14 (93.3%) reported a history of nocturnal erections. Penile color Doppler ultra- sonography demonstrated a normal penile vascular system in 7 (46.7%) and penile arterial insufficiency in 4 (28.6%). All 11 of these patients (73.3%) achieved an adequate erectile response to ICI combined with manual stimulation. Mixed vascular disease was observed in the remaining 4 patients (28.8%), and they did not have a sufficient erectile response to ICI. Color Doppler ultrasonography revealed similar results in the hypogonadotropic and hypergonadotropic men. Conclusions. Our data suggest that the erectile response to ICI combined with manual genital self- stimulation is effective in most hypogonadal men having a micropenis with low serum androgen levels. UROLOGY 61: 426–430, 2003. © 2003, Elsevier Science Inc. M icropenis is defined as an abnormally small, but otherwise anatomically normal, penis with the urethra opening at the tip of the glans. 1 This congenital anomaly must be distinguished from a small but hypospadiac penis, because the term microphallus is used. A webbed scrotum anomaly, as well as a penis buried within the abun- dant mass of prepubic fat, can also give the illusion of a small penis. 1 Combined data from several case reports revealed that approximately 50% of all pa- tients with micropenis have hypogonadotropic hy- pogonadism, 25% have hypergonadotropic hypo- gonadism, 15% have end organ insensitivity, predominantly due to androgen insensitivity from growth-hormone defects, and 10% are idiopath- ic. 1,2 Three important periods in penile formation are known to be under androgenic control. These are the virilization of the phallic shaft that occurs dur- ing gestational weeks 8 to 12, fetal and early neo- natal phallic growth from week 14 of gestation through 24 months of age, and pubescent phallic growth from 11 to 18 years of age. 1 Androgens also play crucial roles in each step of the erection pathway. 3 Androgen deficiency in men can result in loss of libido, as well as erectile dysfunc- tion of varying degrees, and androgen replacement may restore these conditions. 4–6 Moreover, signifi- cant decreases in both pharmacologically induced and neurogenic-mediated erectile responses in cas- trated animal models have been reported. 7–9 From the Department of Endocrinology, Cerrahpas ¸a Faculty of Medicine, Cerrahpas ¸a; and Department of Urology, University of Istanbul Faculty of Medicine, Istanbul, Turkey Reprint requests: Ates ¸ Kadıog ˘ lu, M.D., Department of Urology, University of Istanbul Faculty of Medicine, 34390-C ¸ apa, Istan- bul, Turkey Submitted: April 25, 2002, accepted (with revisions): September 19, 2002 ADULT UROLOGY © 2003, ELSEVIER SCIENCE INC. 0090-4295/03/$30.00 426 ALL RIGHTS RESERVED doi:10.1016/S0090-4295(02)02262-8