We all need HGH, the hormone responsible for growth. What exactly does it do?

Human growth hormone (HGH) is a hormone that’s essential to our development. Most people produce enough HGH throughout their lifetime. But for those with a deficiency in growth hormone (or a few other health conditions), taking synthetic HGH can offer a solution.

The FDA has detailed a few approved uses of synthetic HGH, but commonly, it is abused for off-label purposes, such as bodybuilding and athletic enhancement, and to halt the effects of aging.

What does prescription HGH treat, and how does it work? Here’s everything you need to know.

What is HGH?

HGH is a hormone that’s naturally produced by your pituitary gland (a small gland nested at the base of the brain), says Dr. Farah Khatoon, DO, MPH, a pediatric endocrinologist with Lurie Children's Hospital and a clinical assistant professor at the Northwestern University Feinberg School of Medicine.

HGH supports several functions in the body — from growth, to muscle and bone strength, to the distribution of body fat, says Dr. Katie O'Sullivan, MD, an assistant professor of Adult & Pediatric Endocrinology at the University of Chicago.

In children, HGH stimulates linear growth and protein synthesis. It also helps with the breakdown of lipids fat, says O’Sullivan. In adults, HGH helps regulate blood glucose levels, she adds.

Is HGH legal?

Most people naturally produce enough HGH, but there are a few instances in which a doctor might prescribe someone to take synthetic HGH (also known as r-hGH). Growth hormone is administered as a daily or once-weekly injectable medication, says Dr. Yuval Eisenberg, MD, an endocrinologist at UI Health.

For children, the FDA has approved the use of synthetic HGH to treat growth hormone deficiency (GHD), being born small for gestational age, idiopathic short stature, chronic renal insufficiency, Turner Syndrome, SHOX gene haploinsufficiency, Noonan Syndrome and Prader Willi Syndrome, says O’Sullivan.

For adults, synthetic HGH is FDA-approved to treat GHD, HIV-associated cachexia and HIV-associated adipose redistribution syndrome, she adds.

In the U.S., taking injectable HGH for reasons that haven’t been approved by the FDA is illegal. For example, prescription HGH may not be used for bodybuilding, athletic enhancement, or anti-aging purposes.

What does HGH do to a person?

For children who have GHD, synthetic HGH supports organ development and can help get kids back on a reasonable trajectory of linear growth, says Eisenberg. Taking growth hormone has the potential to improve a child’s height until their growth plates have fused, which occurs around puberty, he says.

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GH therapy should begin “at the most reasonably early point in the patient's growth when they're identified to be growth hormone deficient or have idiopathic short stature,” says Khatoon. Usually, treatment continues until the patient has reached their target height, or they have stopped growing, she explains.

However, there are certain cases where GH therapy could be lifelong. For example, a child who has a profound deficiency in growth hormone (especially if they are a cancer survivor with damage to the pituitary gland) may need to continue taking HGH as an adult, Khatoon says.

In adults, the benefits of taking growth hormone are a little more subtle, Eisenberg notes. Adults who have GHD may see possible improvements in bone density, muscle mass and strength, cholesterol profile, and a greater distribution of body fat (with less visceral fat surrounding the organs).

This article originally appeared on USA TODAY: What is HGH? And who needs prescription growth hormone