Q: What is the difference between blood plasma and blood serum? If there is any difference, what will be the blood sugar reading variation in a diabetic patient?

A:Plasma is the fluid component of the blood (the other being cells) that contains a large number of proteins, lipids, ions etc. Serum is the fluid component of the blood that is left after the blood has clotted. In other words, serum is plasma minus the proteins (like fibrinogen etc.) that are consumed during the clotting process. Glucose can be measured in serum provided that serum is separated from cells within 30 minutes otherwise the cells utilise the glucose present @ 7 mg/dl (at room temperature) thus falsely lowering the glucose value. This rate of glucose metabolism is higher in case of bacterial contamination or raised white blood cell count (leukocytosis). If serum is to remain in contact with cells for more that 30 minutes, an additive like sodium fluoride is added that inhibits the enzyme required by cells to metabolise glucose. If there is no bacterial contamination or leukocytosis, a delay of up to 90 minutes does not appreciably affect glucose levels.