Zinc is an essential trace mineral that the body needs for many functions, including immune activity, wound healing, protein production, DNA synthesis, and normal growth and development. A zinc blood test measures the amount of zinc present in the blood, usually in the serum or plasma. Because the body does not store zinc in large amounts, blood levels reflect recent intake and overall balance. This test is used to check whether a person has too little or too much zinc in the blood. Low levels may be looked for in people with symptoms such as poor wound healing, hair loss, skin changes, reduced sense of taste or smell, frequent infections, or in those with conditions that affect nutrient absorption. Higher-than-normal levels may be checked in people with possible excess intake or occupational exposure. The test can also be used to monitor people taking zinc supplements or receiving intravenous nutrition.