Shorter anogenital distance correlates with the severity of hypospadias in pre-pubertal boys.

Abstract

Do pre-pubertal boys with hypospadias have a shorter anogenital distance (AGD) than boys with normal genitalia? AGD is significantly shorter in boys with hypospadias and decreases with the severity of hypospadias. Animal studies have shown that androgen disruption and exposure to endocrine disrupting chemicals during a critical time period in early gestation, termed the male programming window (MPW), result in hypospadias and reduced AGD; and the severity of hypospadias correlates with the reduction in AGD. However, this correlation has not been established in humans. A prospective descriptive study involving measurement of AGD in pre-pubertal boys (n = 458) presenting to our pediatric urology clinic with hypospadias and normal genitalia was performed over a period of 3 years. AGD was measured in pre-pubertal boys from 5 months to 14 years of age presenting to our clinic with hypospadias (n = 180: four were excluded) and compared with randomly selected boys with normal genitalia (controls, n = 274). Three variants of AGD, from the midpoint of the anus to base of the scrotum (AGD-AS), to the anterior base of penis (AGD-1) and to the posterior base of penis (AGD-2), were measured and assessed for correlation with the severity of hypospadias. Severity of hypospadias was classified as anterior, middle and posterior according to the meatal location. No significant difference in weight (P = 0.123), age (P = 0.162) or height (P = 0.591) between the two groups was observed. Only AGD-AS was significantly shorter in boys with hypospadias compared with controls (mean ± SD: 40.6 ± 9.7 mm versus 45.6 ± 9.4 mm, P < 0.001). This relation persisted after adjusting AGD for weight, height and age (β = 0.016, 95% confidence interval: 0.10-0.21; P < 0.001). The Spearman test showed a significant negative correlation for the severity of hypospadias with all the three AGD measures. Analysis of variance between anterior, middle and posterior subgroups showed a significant reduction in mean AGD-AS (P = 0.003) and AGD-2 (P = 0.008). No data were collected pertaining to in utero exposure to endocrine disrupting chemicals (EDCs) or cigarette smoke, or current diet and environmental exposure to EDCs, which may have influenced the AGD. Family history of genital malformation and use of IVF were not known. There may have been a selection bias as only boys presenting to our clinic were included. The findings suggest that prenatal androgens during early gestation influence development of the male reproductive system and support the existence of a MPW in humans. Of the three AGDs, AGD-AS may be the most reliable biomarker of this in utero androgen action. However, no direct link to any specific exposure leading to shortened AGD in pre-pubertal boys with hypospadias could be determined. Further large scale multi-center studies are needed to understand this association better. Funding was from the Hypospadias Foundation. No conflicts of interest to disclose.