Zinc

Overview

Zinc is an essential trace element required for numerous enzymatic reactions, DNA synthesis, immune function, and protein structure stabilization as a cofactor for over 300 enzymes. It plays critical roles in immune cell development, wound healing, taste perception, and antioxidant defense through superoxide dismutase activity. Low serum zinc levels indicate deficiency associated with malnutrition, malabsorption, chronic disease, or increased losses, while high levels suggest overload from supplementation or Wilson disease; serum zinc poorly reflects total body stores. Clinically, zinc measurement guides nutritional assessment, evaluates suspected deficiency in at-risk populations, and monitors parenteral nutrition or repletion therapy.

Clinical Use Cases

  • Assessment of zinc deficiency in malnutrition, alcoholism, or malabsorption syndromes.
  • Monitoring parenteral or enteral nutrition in critically ill patients.
  • Evaluation of chronic diarrhea, inflammatory bowel disease, or short bowel syndrome.
  • Investigation of impaired wound healing, taste disturbances, or alopecia.
  • Screening for acrodermatitis enteropathica or zinc transporter defects.

Specimen Types

  • Serum (most common).
  • Plasma (heparin or EDTA).
  • Whole blood (for intracellular levels).
  • Urine (24-hour for excretion studies).

Measurement Methods

  • Inductively coupled plasma mass spectrometry (ICP-MS).
  • Atomic absorption spectroscopy (AAS).
  • Colorimetric assays.
  • Flame atomic absorption spectrometry.

Test Preparation and Influencing Factors

  • Fasting sample preferred to minimize diurnal variation and postprandial depression.
  • Recent zinc supplementation or denture cream use (zinc-containing) elevates levels.
  • Acute phase response, infection, or inflammation lowers serum zinc.
  • Hemolysis releases intracellular zinc, causing falsely elevated results.
  • Diurnal variation with lowest levels in morning.
  • Pregnancy, oral contraceptives increase serum zinc binding protein.

Synonyms

  • Zn.
  • Serum zinc.

Further Reading