Why the serum is used instead of the plasma in measuring total blood protein ?
Is it unnecessary to measure the clotting factors in measuring total blood protein ?
Hundreds of proteins are dissolved in the plasma. The measurement of protein is done on serum, which is the fluid that remains after plasma has clotted, thus removing fibrinogen and most of the clotting factors. The normal serum protein level is 6 to 8 g/dl. Albumin makes up 3.5 to 5.0 g/dl, and the remainder is the total globulins. Thus, serum total protein measurement is used to help evaluate disorders affecting albumin or immunoglobulin levels. The presence of clotting factors hampers correct estimation of albumin and immunoglobulin levels.