No anticoagulants are added to serum samples, which decreases the preparation cost of the samples relative to plasma samples. Glucose or these other compounds may be the analytes. For example, during coagulation, blood cells consume blood glucose and platelets increase the sample content of compounds like potassium, phosphates and aspartate transaminase by secreting them. Serum preparation can cause measurement errors by increasing or decreasing the concentration of the analyte that is meant to be measured. Īn unknown volume of anticoagulants can be added to a plasma sample by accident, which may ruin the sample as the analyte concentration is changed by an unknown amount. Serum lacks some proteins that partake in coagulation and increase the sample volume. Ĭompared to serum, 15–20% larger volume of plasma can be obtained from a blood sample of certain size. Thus, phosphatase activity cannot be measured if EDTA is used. For example, EDTA binds zinc ions, which alkaline phosphatases need as cofactors. Even if such ions are not the analytes, chelators can interfere with enzyme activity measurements. Chelator anticoagulants like EDTA and citrate salts work by binding calcium (see carboxyglutamic acid), but they may also bind other ions. For example, anticoagulant salts can add extra cations like NH 4 +, Li +, Na + and K + to the sample, or impurities like lead and aluminum. Plasma preparation requires the addition of anticoagulants, which can cause expected and unexpected measurement errors. However, coagulation can be hastened down to a few minutes by adding thrombin or similar agents to the serum sample. Serum sample preparation requires about 30 minutes of waiting time before it can be centrifuged and then analyzed. Plasma preparation is quick, as it is not coagulated. Some of the benefits of serum over plasma Some of the benefits of plasma over serum In addition, some tests have to be done with whole blood, such as the determination of the amount of blood cells in blood via flow cytometry. Some can be done on both, but depending on the test, use of either plasma or serum can be more practical. Some tests can be done only on plasma and some only on serum. serum in medical diagnostics īlood plasma and blood serum are often used in blood tests. Opaqueness is typically due to elevated content of lipids like cholesterol and triglycerides. Plasma is normally relatively transparent, but sometimes it can be opaque. Dark brown or reddish color can appear due to hemolysis, in which methemoglobin is released from broken blood cells. The latter may form due to medicines that are able to form sulfonamides once ingested. Green color can be due to ceruloplasmin or sulfhemoglobin. In abnormal cases, plasma can have varying shades of orange, green or brown. Plasma is normally yellow due to bilirubin, carotenoids, hemoglobin and transferrin. See also: Sulfhemoglobinemia, Methemoglobinemia, and Hyperlipidemia Bags of frozen plasma, from a person with hypercholesterolemia (left) and typical plasma (right) It is of critical importance in the treatment of many types of trauma which result in blood loss, and is therefore kept stocked universally in all medical facilities capable of treating trauma (e.g., trauma centers, hospitals, and ambulances) or that pose a risk of patient blood loss such as surgical suite facilities. Plasmapheresis is a medical therapy that involves blood plasma extraction, treatment, and reintegration.įresh frozen plasma is on the WHO Model List of Essential Medicines, the most important medications needed in a basic health system. Blood serum is blood plasma without clotting factors. Blood plasma has a density of approximately 1,025 kg/m 3 (1.025 g/ml). For point-of-care testing applications, plasma can be extracted from whole blood via filtration or via agglutination to allow for rapid testing of specific biomarkers. The blood plasma is then poured or drawn off. īlood plasma is separated from the blood by spinning a vessel of fresh blood containing an anticoagulant in a centrifuge until the blood cells fall to the bottom of the tube. It plays a vital role in an intravascular osmotic effect that keeps electrolyte concentration balanced and protects the body from infection and other blood-related disorders. , etc.), hormones, carbon dioxide (plasma being the main medium for excretory product transportation), and oxygen. It is mostly water (up to 95% by volume), and contains important dissolved proteins (6–8% e.g., serum albumins, globulins, and fibrinogen), glucose, clotting factors, electrolytes ( Na + It is the intravascular part of extracellular fluid (all body fluid outside cells). It makes up about 55% of the body's total blood volume. Blood plasma is a light amber-colored liquid component of blood in which blood cells are absent, but which contains proteins and other constituents of whole blood in suspension.
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