Why isn't my son's penis growing with age?

Q: My son is 13 years old. After his birth it was noticed that the opening for the urine passage is not of normal size. We consulted a local doctor who advised a minor operation. After the operation the problem in passing urine was over. But later on we noticed that there was no growth of the penis. We are quite afraid of his future life. How can this defect be rectified?

A:Puberty is the stage of physical maturation in which an individual becomes physiologically capable of sexual reproduction. These biological changes occur due to several neurosecretory factors and/or hormones, all of which affect body growth and development of the sexual glands. Puberty is considered precocious if these changes occur earlier than the age of 8 years in girls/9 years in boys and is considered delayed when such changes do not occur till 13 years in girls and 14 years in boys.Growth starts from early puberty but occurs maximally only around 14 to 15 years of age. Progressively, there is an increase in the size of testis and a testicular volume of 4 ml or a longitudinal diameter greater than or equal to 2.5 cm with a slight progressive increase in scrotal folds and pigmentation constitute the first signs of puberty. This is followed by change in penile size and growth of pubic hair several months later. Axillary hair appears around 13 years of age and change in voice pitch, and acne is frequent. Finally, spermarche (sperm production) occurs at a mean age of 14 years.His earlier surgery has nothing to do with this. In case there is delayed development, please consult a pediatric endocrinologist.