Serum, Leucocyte, Sweat and Hair Zinc Levels a Correlational Study

Howard JMH
J. Nutr. Med. 1990;1:119-126


Doctors investigating the zinc status of their patients must not rely on serum zinc levels which will only identify quite severe deficiencies. Low hair zinc levels do reflect deficiencies, but a normal or high level of zinc in the hair cannot exclude a deficiency due to the affect on hair growth rate. High hair zinc should alert one to the possibility of a zinc deficiency, but there are many shampoos and other cosmetic treatments that contain zinc. A high hair zinc may also reflect other causes of poor hair growth rate such as hypothyroidism or zinc or iron deficiency.

Both sweat zinc and leucocyte zinc levels are good tests of zinc status, with sweat the sample of choice in this study. If the different populations of white cells are separated and analysed independently, my initial studies suggest that white cell zinc may be as good as sweat zinc in assessing zinc status. The collection of sweat samples and the harvesting of uncontaminated white cell fractions from blood samples are both time-consuming and difficult procedures. Deciding which of these techniques to use in a particular clinical laboratory may depend on which technique the staff are most conversant with. I would encourage those laboratories with the necessary analytical equipment to pursue the use of sweat zinc measurements. If they are also willing to measure leucocyte zinc, then the combination of the two techniques will provide a very high level of service for the assessment of zinc status.

One advantage of the sweat test procedure is that it is non-invasive and hence very suitable for use with children or nervous patients.

I hope that the comparison of results for hair, serum, leucocyte and sweat zinc levels will be helpful to those considering a diagnosis of zinc deficiency. Laboratories are under increasing pressure to assess zinc status, and this work may help those responsible for introducing the techniques to avoid some of the pitfalls when the wrong choice of sample is made.

Finally, I wish to emphasise the danger of relying on the serum zinc levels as an indicator of zinc status.

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