Insulin-like Growth Factor 1, also known as IGF-1, is used as a biomarker for blood levels of human growth hormone. It is a hormone produced by the liver and other tissues which affects growth-promoting activities and glucose metabolism. The blood level of IGF-1 appears to fluctuate over 24 hours and is found to be related to growth hormone secretion.

The adrenal gland produces a hormone known as dehydroepiandrosterone (DHEA). It is also made in the brain. DHEA leads to the production of androgens and estrogens (male and female sex hormones). DHEA levels in the body begin to decrease after age 30. Lower DHEA levels are found in people with hormonal disorders, HIV/AIDS, Alzheimer's disease, heart disease, depression, diabetes, inflammation, immune disorders, and osteoporosis. Corticosteroids, birth control taken by mouth, and agents that treat psychiatric disorders may reduce DHEA levels.

A single fasting growth hormone (GH) level is of limited value. The secretion of GH is episodic and pulsatile. GH has a half-life of 20 to 25 minutes. Testing for growth hormone deficiency or excess is best done as part of a dynamic test involving specific stimuli (see the online Endocrine Appendices: Growth Hormone Stimulation and Growth Hormone Suppression). Insulin-like growth factor-1 can also be useful in assessing growth hormone status.