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.

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.

The serum iron test measures the amount of iron in your blood. The total iron-binding capacity (TIBC) test looks at how well the iron moves through your body.