What is the clinical utility of obtaining a serum zinc level?

From the Guidelines

Measuring zinc levels is crucial for patients with increased gastrointestinal and/or skin losses, particularly those on long-term parenteral nutrition, as it helps identify zinc deficiency and guide supplementation. According to the most recent and highest quality study 1, zinc measurement should be done in patients with increased gastrointestinal and/or skin losses on commencing long-term parenteral nutrition, and repeated as required depending on the presence of conditions associated with risk of deficiency.

Key Points to Consider

• Zinc testing is particularly valuable for patients with conditions that increase deficiency risk, such as malabsorption disorders, alcoholism, chronic kidney disease, or those taking medications that deplete zinc 1.
• Serum zinc is the most common test, though it has limitations as zinc is primarily intracellular, and simultaneous determination of CRP and albumin is required for interpretation 1.
• Normal serum zinc ranges from 70-120 μg/dL, with levels below 70 μg/dL suggesting deficiency, and supplementation (typically 25-50 mg elemental zinc daily for adults) may be recommended, with follow-up testing to ensure normalization.
• Interpretation should consider that zinc levels fluctuate with meals, stress, and inflammation, potentially causing falsely low readings during acute illness.

Patient Groups that Benefit from Zinc Level Measurement

• Patients on long-term parenteral nutrition, with measurements every 6-12 months 1.
• Patients undergoing bariatric surgery, with monitoring at least annually following surgery 1.
• Patients with unexplained symptoms, such as anaemia, hair loss, or changes in taste acuity 1.

From the FDA Drug Label

Monitor zinc concentrations and signs and symptoms of zinc deficiency, especially in pediatric patients, during treatment. 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 utility in obtaining zinc levels is to monitor zinc concentrations and signs and symptoms of zinc deficiency, especially in pediatric patients, during treatment with zinc sulfate injection. This is important to ensure that patients are receiving adequate zinc supplementation and to prevent zinc deficiency or toxicity. Key points to consider when obtaining zinc levels include:

• Proper sample collection and processing to avoid falsely elevated results due to hemolysis
• Comparison to laboratory reference ranges, such as the lower end of the reported range in healthy adults in serum (60 mcg/dL)
• Monitoring in pediatric patients, who may be at higher risk for zinc deficiency 2

From the Research

Utility of Obtaining Zinc Levels

The utility of obtaining zinc levels is crucial in assessing zinc status and diagnosing zinc deficiency, which affects a significant portion of the global population 3, 4, 5, 6, 7.

• Zinc is an essential micronutrient required for numerous critical health functions in the body, and its deficiency can lead to various health problems, including impaired immune function, wound healing, and growth 3, 7.
• The diagnosis of zinc deficiency is based on clinical assessment, symptomatology, and biochemical tests, including the determination of biomarkers such as plasma zinc concentration 4, 7.
• Obtaining zinc levels can help identify individuals at risk of zinc deficiency, particularly those with limited access to zinc-rich foods or with increased zinc requirements due to certain medical conditions 5, 6.
• Zinc supplementation is a convenient and effective option for treating zinc deficiency and maintaining healthy zinc levels, and obtaining zinc levels can help guide supplementation therapy 3, 4, 6.

Importance of Zinc Status Assessment

Assessing zinc status is essential to detect zinc deficiency or excess, which can have significant health consequences 5, 7.

• Zinc deficiency can impair physiologic processes, leading to clinical consequences such as failure to thrive, skin rash, and impaired wound healing 7.
• On the other hand, excessive zinc intake can cause copper deficiency and other adverse health effects 5.
• Obtaining zinc levels can help healthcare providers make informed decisions about zinc supplementation and monitor the effectiveness of treatment 3, 6.

Applications of Zinc Level Assessment

Zinc level assessment has various applications in healthcare, including:

• Diagnosing and treating zinc deficiency and related health problems 4, 7
• Guiding zinc supplementation therapy 3, 6
• Monitoring zinc status in individuals with increased zinc requirements or limited access to zinc-rich foods 5, 6
• Researching the relationships between zinc status and various diseases, such as diabetes mellitus and COVID-19 5, 6