What is the utility of zinc screening in high-risk individuals, such as pregnant women, elderly individuals, and those with gastrointestinal disorders or impaired wound healing?

Utility of Zinc Screening in High-Risk Populations

Zinc screening is clinically useful and should be performed at least annually in high-risk individuals including pregnant women, elderly patients, those with gastrointestinal disorders (particularly malabsorptive conditions), and patients with impaired wound healing, as these populations face increased risk of deficiency that can significantly impact morbidity and quality of life. 1

High-Risk Populations Requiring Screening

Pregnant and Lactating Women

• Screen pregnant women for zinc deficiency as they have increased requirements and are at elevated risk of depletion 1
• Zinc deficiency during pregnancy can lead to growth retardation, delayed sexual development, and impaired immune function in offspring 1
• Maintain zinc supplementation throughout pregnancy without interruption, as discontinuation has resulted in serious complications 1

Gastrointestinal Disorders

Screen patients with the following conditions at least annually: 1

• Short bowel syndrome
• Bariatric surgery (particularly malabsorptive procedures like RYGB, BPD/DS, or sleeve gastrectomy) 1
• Inflammatory bowel disease
• Chronic pancreatitis
• Cystic fibrosis
• Enterostomy, enterocutaneous fistula, or chyle leaks
• Chronic diarrhea

Additional High-Risk Groups

Screen the following populations regularly: 1

• Elderly individuals (increased risk due to decreased intake and absorption)
• Patients on prolonged parenteral nutrition
• Patients with chronic renal disease or on dialysis 1
• Alcoholics and those with alcoholic cirrhosis 1
• Burn patients (>20% BSA) with exudative losses 1
• Patients with eating disorders (anorexia nervosa, bulimia) 1
• Vegetarians and vegans (diet rich in phytates that inhibit zinc absorption) 1, 2

Clinical Manifestations Warranting Screening

Severe Deficiency Signs

Screen immediately if patient presents with: 1

• Alopecia or unexplained hair loss 1
• Characteristic skin rash (face, groins, hands, feet)
• Impaired wound healing or poor wound healing 1
• Diarrhea
• Blunting of taste and smell or changes in taste acuity 1

Mild to Moderate Deficiency Signs

Consider screening if patient has: 1

• Reduced growth rate (children and adolescents)
• Impaired immune function or increased susceptibility to infections 1
• Unexplained anemia 1
• Mental lethargy 3

Screening Methodology

Laboratory Testing

• Measure serum or plasma zinc levels as the primary screening tool 1
• Normal serum zinc concentrations range from 10.7 to 22.9 μmol/L (70-150 μg/dL) 1

Critical Interpretation Caveat

Always check inflammatory markers (CRP or AGP) simultaneously with zinc levels 1

• Serum zinc decreases significantly when CRP exceeds 20 mg/L due to acute phase response 1
• Zinc redistributes from plasma to liver during inflammation, causing falsely low values 1
• Use BRINDA adjustment equations when inflammation is present to interpret results accurately 1

Monitoring Frequency by Population

Post-bariatric surgery patients: 1

• Check at 3,6, and 12 months in the first year
• At least annually thereafter

Patients with gastrointestinal losses (fistulae, stomas, diarrhea): 1

• Monitor regularly while losses persist
• May require IV supplementation up to 12 mg per day 1

Malabsorptive procedures (BPD/DS): 1

• Every 3 months initially, then annually once stable

Common Pitfalls to Avoid

Interpretation Errors

• Do not interpret low zinc levels without checking inflammatory markers - inflammation causes redistribution and falsely low values 1
• Erythrocyte zinc concentrations show little change in deficiency states despite significant plasma zinc decline, making them unreliable 1
• Hair zinc is contaminated easily and not used in hospital practice 1

Overlooked Deficiency States

• Acquired zinc deficiency is potentially underdiagnosed 1
• Patients on chronic parenteral nutrition without adequate zinc supplementation are at high risk 1
• Prolonged renal replacement therapy causes deficiency 1

Drug Interactions

• Antacids and medications that decrease iron absorption also affect zinc 1
• Many drugs increase urinary zinc losses 1
• Monitor serum copper when supplementing zinc, as high zinc intake causes copper depletion 1, 4

Impact on Morbidity and Quality of Life

Immune Function

• Zinc deficiency affects both innate and adaptive immunity at cellular survival, proliferation, and maturation levels 1
• Monocytes, polymorphonuclear cells, natural killer cells, T-cells, and B-cells are all affected 1
• Acute deficiency decreases immunity while chronic deficiency increases inflammation 1

Wound Healing

• Zinc is essential for protein and DNA synthesis required for wound healing 3
• Screening is particularly important in surgical patients and those with chronic wounds 1

Growth and Development

• Infants, children, and adolescents have increased requirements and are at elevated risk 1
• The only clearly demonstrated signs of mild deficiency are reduced growth rate and impaired immune defense 1