Hair as a biopsy material: trace element data on one man over two decades.

Background: Hair mineral analyses are being performed frequently both with and without medical advice. Reasons for analysis often are ill defined. Objective: To assess variability of trace element data both within a series of samples from an individual and among mean values published from other research laboratories. Design: Many samples of hair were collected carefully from a healthy man over a comparatively long period of time and were processed and analyzed under standard conditions. Extensive published data from other research laboratories also were reviewed and compared. Results: Coefficients of variation for trace elements in hair of the donor ranged from 17 to 74% for the essential elements copper, selenium and zinc and from 53 to 121% for the potential intoxicants aluminum, cadmium and lead. The ratio of high mean to low mean for values published by others on hair samples from healthy people ranged from two for selenium and zinc to 18 for aluminum. Conclusions: Hair analysis should be based on a diagnostic hypothesis such as cadmium intoxication or copper deficiency rather than on the ease of analysis or attempts to explain vague symptoms because within-person variability is large and interlaboratory agreement on normal values is poor.