Concentration homeostasis and elements in hair and dried serum observed by X-ray fluorescence analysis using synchrotron radiation.

Elemental concentrations in hair and dried serum have been evaluated by X-ray fluorescence analysis using relative concentration independent of specimen thickness. Dried serum samples from 5 male and 5 female subjects given two-week Ca supplementation showed the same concentration for Ca, and for each of the other elements Cl, K, S and P under renal control by parathyroid hormone (PTH). Hair concentrations of these elements have been evaluated for 50 randomly-selected females aged between 30 and 80. It was found that each element has two distinct levels in hair. The content of an element in growing hair must be equal to the inflow of that element into the hair-making cells from serum. Using this principle, the two levels can be attributed to the gating and closing of the ion channels in cell membranes and given as functions of the dried serum standard concentrations. Especially, the difference between [Ca] and [Sr] in hair shows whether Ca channels are gating or closing. The lower level of hair [Ca]_H is normal and is equal to 1/2 of the dried serum [Ca]; only the Ca on serum protein is to be incorporated into the hair in steady-state growth. Store-operated Ca channel gating occurs so as to maintain the normal [Ca]_H. The higher level is seen in cases of calcium deficiency, and implicated in other disease states. Prolonged Ca deficiency causes a higher hair [Ca]_H with Ca channel closing. PTH-operated Ca channel gating induces the Ca^{2+} inflow into the cells to form the hair [Ca]_H upper level and to deteriorate cell functions such as excretion of excess metals by hepatocytes. Hair analysis provides a new diagnostic tool based on cell ion channels.