Research article

Trace elements in hemodialysis patients: a systematic review and meta-analysis

Marcello Tonelli¹ , Natasha Wiebe¹ , Brenda Hemmelgarn² , Scott Klarenbach¹ , Catherine Field³ , Braden Manns² , Ravi Thadhani⁴ and John Gill⁵ for The Alberta Kidney Disease Network

¹Department of Medicine, University of Alberta, Edmonton, Alberta, Canada

²Department of Medicine, University of Calgary, Alberta, Canada

³Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada

⁴Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA

⁵Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada

author email corresponding author email

BMC Medicine 2009, 7:25doi:10.1186/1741-7015-7-25

Published:	19 May 2009

Abstract

Background

Hemodialysis patients are at risk for deficiency of essential trace elements and excess of toxic trace elements, both of which can affect health. We conducted a systematic review to summarize existing literature on trace element status in hemodialysis patients.

Methods

All studies which reported relevant data for chronic hemodialysis patients and a healthy control population were eligible, regardless of language or publication status. We included studies which measured at least one of the following elements in whole blood, serum, or plasma: antimony, arsenic, boron, cadmium, chromium, cobalt, copper, fluorine, iodine, lead, manganese, mercury, molybdenum, nickel, selenium, tellurium, thallium, vanadium, and zinc. We calculated differences between hemodialysis patients and controls using the differences in mean trace element level, divided by the pooled standard deviation.

Results

We identified 128 eligible studies. Available data suggested that levels of cadmium, chromium, copper, lead, and vanadium were higher and that levels of selenium, zinc and manganese were lower in hemodialysis patients, compared with controls. Pooled standard mean differences exceeded 0.8 standard deviation units (a large difference) higher than controls for cadmium, chromium, vanadium, and lower than controls for selenium, zinc, and manganese. No studies reported data on antimony, iodine, tellurium, and thallium concentrations.

Conclusion

Average blood levels of biologically important trace elements were substantially different in hemodialysis patients, compared with healthy controls. Since both deficiency and excess of trace elements are potentially harmful yet amenable to therapy, the hypothesis that trace element status influences the risk of adverse clinical outcomes is worthy of investigation.