The effects of inheritance on constituents of plasma: a twin study on some biochemical variables.

Heritability and within-person repeatability of thirteen constituents of plasma were assessed in a study of 206 pairs of male and female twins. Repeat measurements were available on 44 pairs. For bilirubin, calcium, creatinine, phosphate and potassium, the individuality of these characteristics was genetic in origin. Total protein, albumin and globulin showed significant heritability but considerable variation between occasions, while bicarbonate, chloride, iron, sodium and urea showed mainly environmental effects.