Ferritin is a protein that stores iron. Red blood cells need iron to form normally and carry oxygen around your body. Low levels of ferritin lead to iron deficiency anemia, which means you have too few red blood cells. High levels of ferritin can damage your joints, heart, liver, and pancreas.

Cortisol (hydrocortisone) is the most prominent glucocorticosteroid, and it is essential for the maintenance of several body functions. The most important physiological effects of cortisol are that it raises blood sugar levels (enhances gluconeogenesis, or breaks down glucose) and lowers inflammation and the immune system.

B12 and folic acid blood testing help doctors diagnose central nervous system disorders, anemia, and malabsorption syndromes. B12 and folic acid also play an important role in energy level, muscle strength and memory. Because B12 and folate are derived solely from dietary intake, such as egg yolks, beef, poultry and fish, many people are deficient in these important vitamins.

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.