Effect of venous occlusion of the arm on the concentration of calcium in serum, and methods for its compensation.

Data are presented on the effects on 12 normal subjects of a 3-mm period of venous occlusion of the arm. Concentrations of both total calcium and total protein in serum are significantly increased, while serum magnesium and phosphorus and plasma ionic calcium concentrations remain unchanged. Concentrations of both total calcium and total protein are significantly greater in the serum of men than of women. The use of methods of adjusting calcium for changes in total protein concentration, as devised by Dent and by Parfitt, eliminate changes in these values because of venous occlusion and sex-related differences. Normal ranges for serum total calcium adjusted according to these methods are based on findings in 87 normal subjects (43 men and 44 women). The clinical usefulness of such adjustments in serum calcium measurements is discussed.