Stretched penile length and anogenital distance in Egyptian boys aged one month to five years.

BACKGROUND: In children with isolated unilateral undescended testis mechanical anomalies are commonly implicated and a diagnosis of simple hypospadius implies that the rest of the external genitalia are normal. Patients with disorders of sexual development, by contrast, have other associated genital anomalies including micropenis and should be referred to the endocrinologist for hormonal assessment before surgical correction of undescended testis or hypospadius. Early diagnosis of abnormal penile size is important but proper assessment begins with defining the normal population-specific age-appropriate reference range. Anogenital distance (AGD) reflects prenatal and early postnatal testosterone levels.

OBJECTIVE: The aim of our study was to establish mean reference values and percentile curves for strtetched penile length (SPL) and AGD in healthy Egyptian males from the age of one month to five years and to determine the mean monthly increase in SPL and AGDs from 1 to 13 months of age (a reflection of mini-puberty).

STUDY DESIGN: This was a descriptive cross-sectional study conducted in Cairo University and Mataria Hosptals, Egypt to determine SPL and AGD in 2972 Egyptian males aged from one month to five years from October 2016-December 2018. In addition, we measured length/height, weight and body mass index.

RESULTS: SPL increased gradually from a mean ± SD of 3.55 ± 0.51 cm in the first year of life to 5.52 ± 0.67 cm by five years of age with a growth from 1 to 12 months of life of 0.6 cm. SPL showed smaller values in infants 6-9 months old compared to younger infants. AGD increased from 7.48 ± 1.47 cm in the first year of life to 12.83 ± 0.58 cm by 5 years of age with a growth from 1 to 12 months of 4.34 cm. SPL and AGD Z-scores correlated positively with each other and with age (months), and Z-scores of height/length, weight and BMI (p < 0.001).

DISCUSSION: The rapid increases in SPL and AGD observed in our study group in the first few months of life reflect the effects of mini-puberty. The fact that SPL and AGD correlated positively with other anthropometric measurements suggests that SPL and AGD may be controlled by nutritional and/or hormonal factors. We suggest that waning testosterone levels marking the end of minipuberty might explain smaller values for SPL in our group of 6-9 month old infants compared with younger infants.

LIMITATION: We have not included children under one month old.

CONCLUSION: It is important for each country to develop its own national percentile curves for all growth parameters. This will allow the physician to identify normal differences in the population and to pick up disorders at an age when intervention may yield better results We have developed percentile curves for SPL and AGD that can be used as references for Egyptian male infants and young children.