What is IGF-1?
Growth Hormone exerts many of its effects through a peptide hormone called Insulin-like growth factor 1. IGF-1 is used as a marker for growth hormone levels as it is difficult to measure them due to its fluctuating pulsatile release. IGF-1 acts on the chondrocytes to stimulate bone mineralization increases lean muscle mass and at high doses can cause organomegaly.
Increased levels of IGF-1 can be beneficial to a certain extent beyond which it can cause pathological changes that can resemble acromegaly leading to an early death from cardiovascular diseases. But a deficiency of IGF-1 can also be equally harmful as it causes a decrease in bone mineral density, lean muscle mass, and atrophy of vital organs. HGH deficiency in itself can result in increased fat deposition and lethargy in addition to the subsequent IGF-I deficiency symptoms.
What causes a decline in IGF-1 levels?
IGF-I levels decline progressively after 60 along with its inducer growth hormone. Their combined inter-related deficiency can result in increased fat deposition in adipocytes, decreased lean muscle mass, lethargy, atrophy of muscles and vital organs, pathological fracture due to osteoporosis, vertebral compression fractures and so on. Although the adverse effects of growth hormone deficiency in older adults have been known for some time, there have been limited studies that have researched any potential remedies for this condition.
Study on Growth Hormone Therapy in Older Adults
Researchers conducted a study to evaluate the role and efficacy of growth hormone replacement in healthy older men with declining levels of IGF-I.
Methodology: 21 healthy men between 61 to 81 years old with plasma IGF-I concentrations of less than 350 U per liter were treated with biosynthetic growth hormone replacement therapy. During the treatment course, the 21 men were divided into two groups. The first group comprised of 12 men were treated with 0.03 mg/kg of HGH subcutaneously thrice a week. The second group of 9 men was not treated with any HGH therapy. In both groups, plasma IGF-I levels were measured on a monthly basis. In addition to this, both groups of men underwent regular measurements of lean body mass, adipose tissue fat mass, the thickness of skin, and bone mineral density.
Results: As expected, the first group treated with HGH therapy had a rise in plasma IGF-I levels to 500-1500 U per liter while the second group had no changes in plasma IGF-I levels. In the first group, lean body mass increased by 8.8 percent, adipose tissue fat mass decreased by 14.4 percent and vertebral body bone mineral density increased by 1.6 percent. No changes in any of the above parameters were found in the second group who had not received any treatment.
Does Growth Hormone Replacement have any adverse effects?
As with any medication, growth hormone therapy also carries possible risk factors when given for long durations. Possible HGH side effects include worsening of pre-existing heart conditions such as cardiomegaly which can result in hypertension and sudden cardiac death from dangerous arrhythmia. Development of Diabetes is also possible as growth hormone has diabetogenic properties due to its anti-insulin effects. In the above study, none of these conditions were seen in the participants undergoing growth hormone therapy but there was a small elevation in the fasting blood glucose level as well as in the mean systolic pressure in group 1.
Is it safe to recommend growth hormone therapy in all older adults?
Growth hormone therapy in older adults is not recommended by the FDA due to the limitation of large scale trials on the efficacy of this treatment in older adults as well as poor data on the long term effects of this therapy. But safer alternatives to increase growth hormones such as exercise, adequate sleep, the diet may be enough to raise growth hormone levels to a degree that can delay the adverse effects of growth hormone deficiency in aging populations.