Iatrogenic copper deficiency: Risks and cautions with zinc prescribing

AIMS

Copper deficiency resulting from prescribing zinc in high doses is a rare but life-changing diagnosis that is frequently overlooked. The aim of this study is to gauge how often zinc-induced copper deficiency is missed, to raise awareness of the condition and to stress the need for guidelines for prescribing zinc.

METHODS

Suspected cases of zinc-induced copper deficiency were retrospectively obtained by selecting those patients with hyperzincaemia and hypocupraemia from the database of the Scottish Trace Element Laboratory. Case records were reviewed to determine the validity of the suspected diagnosis.

RESULTS

After exclusions, 23 instances of high serum zinc and low serum copper concentrations were found. A positive diagnosis of zinc-induced copper deficiency was made in 14 patients, of which 7 (50%) were previously undiagnosed.

CONCLUSION

Serum zinc and copper concentrations are rarely measured in patients prescribed zinc and so the vast majority of cases of zinc-induced copper deficiency are likely to be undiagnosed. We recommend the current official advice on the dose and frequency of zinc administration is revised in order to limit, and potentially eradicate, the condition.

Recommended Reference Intervals for copper and zinc in serum using the US National Health and Nutrition Examination Surveys (NHANES) data

BACKGROUND AND AIMS

In view of the wide variations in reference intervals (RIs) for copper and zinc concentrations in serum, this study was designed to derive appropriate RIs that could be routinely adopted in other laboratories, so allowing better interpretation of results. A secondary aim was to assess the effects of several variables on serum concentrations of copper and zinc.

MATERIALS AND METHODS

Data from over 21,000 individuals were downloaded from four National Health and Nutrition Examination Surveys conducted by the US Centers for Disease Control and Prevention. After controlling for the effects of several variables, age and gender-related RIs were calculated.

RESULTS

A comprehensive list of reference intervals of copper and zinc in serum is provided. Serum copper concentrations were affected by age, gender, ethnicity, pregnancy, use of oral contraceptive pill, health status and smoking (in males). Serum zinc concentrations were affected by gender, age, fasting, ethnicity, serum albumin concentration, health status (in males), time of venipuncture and pregnancy.

CONCLUSION

Reliable RIs for copper and zinc in serum were derived. As analytical accuracy and precision were assured and optimal sample collection protocols were followed, these RIs can be transferred for routine use in other clinical biochemistry laboratories with good analytical performance in external quality assurance schemes.

Cytopenia associated with copper deficiency

Introduction

Due to an increased incidence of copper deficiency, we investigated adult patients who had low serum levels of copper with cytopenia at our hospital from March 2014 to March 2021.

Methods

We retrospectively reviewed the clinical data of patients who had been diagnosed with cytopenia due to copper deficiency at the Aichi Medical University Hospital from March 2014 to March 2021.

Results

In the 15 patients with cytopenia secondary to low serum copper level, 11 had cytopenia of two to three lineages; three (27%) had pancytopenia, and eight (73%) had bicytopenia. Of the 15 patients, nine (60%) underwent bone marrow examinations; three (30%) showed typical morphologic features associated with copper deficiency, such as multiple clear cytoplasmic vacuoles in erythroblasts and myeloid cells, and three (30%) showed dysplastic features as observed in myelodysplastic syndrome. Among the 14 (93%) patients who were treated with copper supplements, had cessation of zinc supplements, or both, 11 (73%) and eight (53%) showed normal copper levels and hematological improvement, respectively.

Conclusion

Copper deficiency is more common than expected and should be considered in patients with unexplained cytopenia.

Wilson disease: copper deficiency and iatrogenic neurological complications with zinc therapy

A 17-year-old female was diagnosed with Wilson disease and commenced on oral zinc therapy. She re-presented 6 months later with a fall and had classical signs of subacute combined degeneration of the spinal cord confirmed on nerve conduction studies, as a result of zinc-induced copper deficiency. After 6 months of copper therapy, she made a complete recovery with no residual neurological deficits. Early detection of zinc-induced copper deficiency and stringent follow-up mechanisms are crucial. Early initiation of copper replacement may both limit and completely reverse neurological deficits.

Zinc preconditioning protects against renal ischaemia reperfusion injury in a preclinical sheep large animal model

Ischaemia-reperfusion injury (IRI) during various surgical procedures, including partial nephrectomy for kidney cancer or renal transplantation, is a major cause of acute kidney injury and chronic kidney disease. Currently there are no drugs or methods for protecting human organs, including the kidneys, against the peril of IRI. The aim of this study was therefore to investigate the reno-protective effect of Zn²⁺ preconditioning in a clinically relevant large animal sheep model of IRI. Further the reno-protective effectiveness of Zn²⁺ preconditioning was tested on normal human kidney cell lines HK-2 and HEK293. Anaesthetised sheep were subjected to uninephrectomy and 60 min of renal ischaemia followed by reperfusion. Sheep were preconditioned with intravenous injection of zinc chloride prior to occlusion. Serum creatinine and urea were measured before ischaemia and for 7 days after reperfusion. HK-2 and HEK293 cells were subjected to in vitro IRI using the oxygen- and glucose-deprivation model. Zn²⁺ preconditioning reduced ischaemic burden determined by creatinine and urea rise over time by ~ 70% in sheep. Zn²⁺ preconditioning also increased the survival of normal human kidney cells subjected to cellular stress such as hypoxia, hydrogen peroxide injury, and serum starvation. Overall, our protocol incorporating specific Zn²⁺ dosage, number of dosages (two), time of injection (24 and 4 h prior), mode of Zn²⁺ delivery (IV) and testing of efficacy in a rat model, a large preclinical sheep model of IRI and cells of human origin has laid the foundation for assessment of the benefit of Zn²⁺ preconditioning for human applications.