Micropenis is defined as a penis that has developed normally in terms of structure and appearance, but is smaller than the normal range for an infant. Normally, a full term newborn boy's penis measures between 2.8 to 4.2 cm long when carefully stretched and measured from the tip to the base of the penis. A penis smaller than 1.9 cm long is usually considered micropenis.
Genital development involves a complex sequence of events that are dictated by chromosomes and hormones. If the body does not produce enough androgens (the hormones that cause male genital development) or if the body does not react fully to the hormones produced, the development of the genitalia will be affected. Micropenis is likely caused by an insufficient production of androgen during fetal development.
Diagnosis is usually made by physical examination. It is important to have your child diagnosed by a doctor. Many times, the doctor’s evaluation finds that the penis size is very much within the normal range. A penis may appear smaller than average if the child has a large suprapubic fat pad. Your child will be evaluated by a urologist through our program for Disorders of Sex Development. We will help facilitate an evaluation with an endocrinologist (a physician who specializes in hormones) if necessary.
Specific treatment for micropenis will be determined by your child's physician. Hormone therapy may be indicated for some children to stimulate penile growth.
Our team includes a psychologist who will be available to you and your child to help facilitate healthy adjustment to this condition over time.
Reviewed by: Division of Urology
Date: June 2011