The age-related decline in growth hormone is well established and is associated with loss of muscle and bone mass, but it is not a disease that needs to be treated. Growth hormone supplementation in healthy older adults provides barely any functional benefit and carries real risks, including side effects and an increased chance of cancer. Animal research even suggests that lower growth hormone activity in later life may contribute to a longer lifespan, although that has not yet been conclusively demonstrated in humans.
Growth hormone declines substantially as you get older. In people over sixty, average levels measured across a full day often fall below the detection threshold of standard measurement methods, comparable to patients who have a clinical deficiency caused by a pituitary disorder. This ageing process has been given its own name: the somatopause. Levels in old age amount to roughly twenty percent of what they were during puberty.
That decline is not without consequences. Growth hormone, together with the growth factor IGF-1, drives the building of muscle and bone. Lower levels are associated with loss of bone mineral density and muscle mass as one gets older. Whether the hormonal decline is the cause or merely accompanies broader ageing processes has not been definitively established, but the association is consistent enough to take seriously.
The obvious question is therefore: can you turn back the clock by supplementing the hormone? The short answer is: barely, and not without risk. Clinical studies of growth hormone injections in healthy older adults show at most a modest increase in lean mass, but no meaningful improvement in muscle function or quality of life. Most of these studies also lacked a placebo group, which further limits the value of the positive findings.
The safety picture makes the overall picture even more sobering. Growth hormone treatment in healthy older adults is associated with a high incidence of side effects. In addition, higher IGF-1 levels have been linked in population studies to an increased risk of several forms of cancer. This has considerably dampened enthusiasm for correcting the somatopause.
Interestingly, animal experiments point in a surprising direction. Mice with a hereditary growth hormone deficiency live significantly longer than normal counterparts, while mice in which the gene for growth hormone has been made extra active actually show earlier signs of ageing and shorter lifespans. In humans the findings are contradictory, but this makes clear that lower growth hormone activity in later life is not by definition something that needs to be fixed.
Growth hormone treatment in adults is medically indicated only when a deficiency caused by a disorder of the pituitary or hypothalamus has been demonstrated, or in people who have had a deficiency since childhood. The normal age-related decline does not fall under this category. Anyone concerned about muscle loss or bone density is better off looking at strength training and nutrition, because those interventions have a better ratio of effectiveness to risk than hormonal supplementation outside a medical indication.
Based on three to six human studies and animal experiments (PMID 8300054, 36948778, 10905380, 33068640, 9704566). The association between ageing and GH decline is well documented. The evidence for the effects of GH treatment in healthy older adults is limited by small sample sizes and the absence of placebo groups.