A 34-year-old man from Pakistan hit up an endocrinology clinic with an unusual complaint: He had super-scarce facial, armpit, and pubic hair.
When the doctors examined him, they also found his penis was much smaller than average. When stretched—which clinicians often use to mimic erect length—the man’s penis measured just under two inches, according to the case report in BMJ Case Reports. That falls under the micropenis category, meaning a penis length that’s 2.5 standard deviations below the average. (In a 2015 analysis of penis sizes of 15,000 men, that would be anything 3.3 inches or less when stretched.)
Doctors also determined his testicular volume was very low, as were his testosterone levels. The cutoff for low T varies among labs, but anything below 300 nanograms per deciliter (ng/dL) is generally considered diagnostic for low testosterone. This guy’s measured just 55.99 ng/dL.
Other lab work revealed low levels of other reproductive hormones, like luteinizing hormone and follicular stimulating hormone, too. An interview with the man uncovered that he wasn’t ejaculating, and was experiencing fewer morning erections.
The diagnosis? A relatively uncommon disorder called idiopathic hypogonadotropic hypogonadism—where the testes don’t produce enough male sex hormones. They determined he had the idiopathic kind, meaning there were no structural or functional abnormalities in his pituitary gland or hypothalamus responsible for it.
The doctors suggested testosterone injections to get his levels up to normal. After nine months of testosterone therapy, his testicular volume doubled in size, his testosterone levels normalized, and his penis grew to the mean size for adults his age. (According to that 2015 study, the average stretched size is 5.2 inches.) He was able to discontinue therapy.
If you know a guy with signs of low testosterone, he should talk to his doctor about getting his levels checked. If they are low, he might be a candidate for testosterone therapy—and he should see symptoms improve. But it's important to note, if his levels aren't clinically low, it's unlikely upping his T will help.