A micromethod for the quantitative analysis of calcium, magnesium, and phosphorus in human skin

An inexpensive and simple micromethod is described for determining calcium, magnesium, and phosphorus in a 4 mm. punch biopsy of human skin. This small biopsy requires no sutures, and can be repeated frequently with minimal trauma to patients in long-term studies. Normal ranges of calcium (125 to 300 mg. per kilogram of dry defatted weight (DDW), phosphates (450 to 980 mg. per kilogram of DDW), and magnesium (75 to 112 mg. per kilogram of DDW) are similar to reported results on much larger biopsies. Skin calcium but not skin magnesium or phosphate was significantly higher in 40- to 76-year-old subjects when compared to the 20- to 39-year-old individuals. Comparison of an acid extraction method with the standard ashing procedure showed no significant differences in calcium and magnesium content, but the acid extractable phosphate was significantly lower than the total phosphorus found in the ash.