A Pakistani man saw his penis size double in nine months after being given regular injections of testosterone.

Due to a lack of the male hormone, the unnamed patient had just a 5cm-long (two inches) member at full stretch - equivalent to a 12-year-old.

But after doctors corrected the 34-year-old's lack of testosterone, they were able to expand it to 9.1cm - dubbed the average size.

The 5'7 patient, believed to be from Karachi, initially sought medical help when he became frustrated that he couldn't grow a beard.

Due to a lack of the male hormone, the unnamed 34-year-old had just a 5cm-long (two inches) member at full stretch. But after doctors found the cause of his lack of testosterone, they were able to expand it to 9.1cm - dubbed the average size.

AVERAGE PENIS SIZES FLACCID: Age 12: 5cm (2 inches) Age 15: 8cm (3.1 inches) Adults: 9.1cm (3.6 inches) ERECT: Age 12: 10cm (4 inches) Age 15: 11.8 (4.6 inches) Adults: 13.12cm (5.16 inches) Note: These figures are compiled from a range of websites and studies. Advertisement

He also had just a few armpit hairs and was relatively scarce in the pubic region, experts wrote in the BMJ Case Reports.

Because he wanted to get married soon, he presented himself to his doctor to combat his embarrassing symptoms.

The man was also concerned about having less erections when he woke up in the mornings and absent ejaculations - a reduced supply of sperm.

The man is 'unusual'

Doctors, who said it was 'unusual' to see such symptoms in men that age, measured his penis and testicular volume.

The man was between the normal ranges for all hormones except testosterone, which he severely lacked.

He was found to have 55.99 ng/dL of the male hormone. Healthy adult males are supposed to have between 249 and 836.

What is hypogonadism?

As a result of his symptoms, the team at the Aga Khan University Hospital were able to diagnose him with male hypogonadism.

HYPOGONADISM: THE FACTS Male hypogonadism is a condition in which the body doesn't produce enough testosterone. This hormone plays a role in masculine growth and development during puberty. If the body doesn't produce enough testosterone, the result may be impaired growth of the penis. It can develop later on in life through injury or infection, or patients can be born with it. Source: Mayo Clinic Advertisement

This condition is when the body doesn't produce enough testosterone, causing a smaller penis and testicles.

A treatment course of nine months of testosterone replacement therapy was then recommended to him.

He went ahead with it, and was given an injection of 250mg once every four weeks to help boost his count of the hormone.

This later decreased to once every six weeks when the treatment, which the doctors said can impair a man's fertility, was starting to work.

Did treatment work?

At the end of treatment, his testosterone count had increased to 433.8 ng/dL and his penis size had doubled.

The size of his testicles had also doubled, with them having just a 10ml volume - the equivalent of a teenage boy, before he started the injections.

Writing in the journal, the doctors added: 'This hesitancy to seek medical care regarding delayed puberty may be because of the social stigma associated with sexual disorders.

'Therefore, a lot of the cases might go unreported and present at a relatively advanced age.'