From the Guidelines
Plasma zinc levels are typically measured through specialized blood tests, including the serum or plasma zinc test, which is often part of a comprehensive mineral panel or trace element panel. These tests are designed to assess zinc status in the body and can be used to confirm clinical zinc deficiency and monitor adequacy of provision 1. The test may be included in broader panels such as nutritional deficiency panels or metabolic profiles when nutritional status is being evaluated.
Key Considerations for Plasma Zinc Testing
- The blood sample should be collected in the morning after fasting overnight, as zinc levels can fluctuate throughout the day and with food intake 1.
- The sample must be collected in trace element-free tubes to prevent contamination, and the blood should not be hemolyzed as this can affect results.
- Normal plasma zinc levels typically range from 70-120 μg/dL (10.7-18.4 μmol/L) for adults, though reference ranges may vary slightly between laboratories.
- Zinc testing is particularly important for patients with malabsorption disorders, chronic diarrhea, liver disease, or those on long-term parenteral nutrition, as these conditions can lead to zinc deficiency.
Interpretation of Results
- Results should be interpreted together with changes in serum albumin and the magnitude of the inflammatory response (CRP) 1.
- Total zinc can be measured in whole blood, plasma, serum, urine, or hair preferably by ICP-MS, or by atomic absorption spectroscopy 1.
Monitoring and Replacement
- Check serum/plasma zinc levels at regular intervals following certain surgeries, such as sleeve gastrectomy (SG), Roux-en-Y gastric bypass (RYGB), or biliopancreatic diversion with duodenal switch (BPD/DS) 1.
- Consider monitoring serum/plasma zinc levels at least annually following these surgeries.
- Check serum/plasma zinc levels if unexplained anemia, hair loss, or changes in taste acuity occur 1.
From the FDA Drug Label
Monitor zinc concentrations and signs and symptoms of zinc deficiency, especially in pediatric patients, during treatment. Zinc concentrations may vary depending on the assay used and the laboratory reference range. The collection, processing, and storage of the blood samples for zinc analysis should be performed according to the laboratory's sample requirements. Zinc concentrations in hemolyzed samples are falsely elevated due to release of zinc from erythrocytes The lower end of the reported range in healthy adults in serum is 60 mcg/dL.
The blood tests that include plasma zinc levels are those that monitor zinc concentrations. Key points to consider when interpreting these results include:
- Zinc concentrations may vary depending on the assay used and the laboratory reference range.
- Hemolyzed samples can give falsely elevated results due to the release of zinc from erythrocytes.
- The reported range in healthy adults is 60 mcg/dL or higher in serum 2.
From the Research
Blood Tests for Plasma Zinc Levels
The following blood tests include plasma zinc levels:
- Plasma zinc concentration test, which responds in a dose-dependent manner to dietary manipulation in adults, women, men, pregnant and lactating women, the elderly, and those at low and moderate baseline zinc status 3
- Tests that measure zinc status in humans, including plasma zinc concentration, which is a reliable biomarker of zinc status in healthy individuals 3
Limitations of Plasma Zinc Tests
It is essential to note that:
- Plasma zinc levels are influenced by various conditions, including infections and other factors causing stress 4
- Low plasma zinc levels are not always indicative of zinc deficiency 4
- Plasma zinc level determinations should be complemented with zinc concentration determinations in a nucleated tissue, such as liver, muscle, or bone, whenever possible 4
Related Tests
Other tests that may be related to plasma zinc levels include: