Interpretation of plasma protein measurements in end-stage renal disease

Measurement of serum proteins is useful in the diagnosis of malnutrition, iron deficiency and identifying defects in lipid metabolism. Serum albumin, prealbumin and transferrin are reduced by malnutrition. Iron deficiency causes a decrease in serum iron coupled with a decrease in ferritin. Inflammation, however, is common and perhaps more important than malnutrition in altering serum protein composition in patients on dialysis. It causes a decrease in serum albumin, pre-albumin and transferrin as well as a decline in serum iron and a decrease in iron saturation of transferrin, thus obscuring iron deficiency. The presence of inflammation can be best established by measuring CRP, since the levels of this protein change by as much as 1,000-fold during inflammation. Inflammation is suggested by increased levels of fibrinogen, ferritin.