Growth Hormone (hGH)
Growth Hormone or human growth hormone, also known as hGH or somatotropin, is secreted by the pituitary gland into your blood stream where it stays for only a short time before it is metabolized by the liver into somatomedin-C (insulin like growth factor, IGF-1), which stays in the blood a lot longer and is actually the driving force behind all the remarkable properties of hGH. The highest levels are found in the blood during the first 3 to 4 hours hours of sleep at night.
The production of growth hormone peaks during adolescence, reaching around 1.5mg/day, and then gradually drops off after the age of 20 to 25 where it averages around 0.35mg/day and continues to decline by approximately 14% each decade for the rest of your life. By the time you are 60 to 70 years of age you only produce about 15% of the amount produced at your peak. The decline in growth hormone with age is directly associated with many symptoms of aging including wrinkles, grey hair, hair loss, decreased energy, decreased sexual function, loss of muscle mass, increase in body fat, depression, cardiovascular disease, osteoporosis, and overall lower life expectancy.
Low growth hormone has also been related to elevated cholesterol, elevated apoliprotein, thin skin, lack of collagen, decreased nail and hair growth, poor thermo-regulation, dehydration, emotional instability, poor memory, reduced energy, hypoglycemia, insulin resistance, abnormal metabolic rates, to name a few. Low levels of growth hormone causes aging because it is responsible for growth and regeneration of every cell in our bodies.
Some of the functions growth hormone performs in the body include:
It is important to monitor your growth hormone levels as you age to ensure optimal physiological level. There are several ways to determine growth hormone levels however most have many drawbacks. A common way is to measure IGF-1 in serum however this is considered unreliable in thyroid disorders, poorly controlled diabetes, liver disease and malnutrition. Research also indicates about 25% of patients on hGH actually experience a decline in IGF-1 levels. Another way to determine growth hormone levels is via a 24hour urine analysis.