Investigations
1st investigations to order
serum or plasma zinc levels
Test
Serum and plasma zinc levels are the most commonly used tests and the only tests available in routine clinical practice. They are helpful in severe zinc deficiency but are less accurate in marginal deficiency, partly due to issues with protein binding.[48]
Result
<9.2 micromols/L or 10.7 micromols/L (60 micrograms/dL or <70 micrograms/dL) in non-pregnant adults
serum iron level
Test
Other nutrient deficiencies often co-exist with zinc deficiency, including iron deficiency.
Result
low
serum 25-OH vitamin D level
Test
Other nutrient deficiencies often co-exist with zinc deficiency, including vitamin D deficiency.
Although most laboratories report the normal range for 25-hydroxyvitamin D as 50-250 nanomoles/L (20-100 nanograms/mL), evidence supports the goal of >80 nanomoles/L (32 nanograms/mL) based on calcium absorption and parathyroid hormone levels.[52][53]
Result
<80 nanomoles/L (32 nanograms/mL)
serum folate
Test
Folate deficiency may co-exist with zinc deficiency and testing or empirical supplementation should be considered, especially in women of childbearing age.
Result
<7 nanomoles/L (3 nanograms/mL)
serum vitamin B12
Test
Vitamin B12 deficiency may co-exist with zinc deficiency. It may occur in individuals with disease affecting the ileum or in those with diets chronically very low in meat.
Serum vitamin B12 <148 picomols/L (200 picograms/mL) is highly suggestive of vitamin B12 deficiency and generally confirms the diagnosis.
Result
<148 picomols/L (200 picograms/mL)
Emerging tests
cell zinc content
Test
Because 95% of zinc is intracellular, zinc levels in a variety of cell populations (red blood cells, platelets, WBCs) have been evaluated in research settings. Although cellular zinc levels fluctuate less than serum, they are technically more difficult than serum- or plasma-based tests, and superiority has not been clearly demonstrated.[49]
Result
no established reference range
genetic testing for acrodermatitis enteropathica
Test
Genetic testing may be done for mutations in the ZIP4 gene, but is not standard or available in all locations.
Result
mutations in the ZIP4 gene
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