Blood plasma is the clear, yellowish liquid in blood which transports red and white blood cells throughout the body. Plasma also contains blood clotting factors, sugars, fats, vitamins, minerals, hormones, enzymes, antibodies, and an assortment of all the proteins present anywhere in the body. When blood is drawn and allowed to clot, the yellow liquid which is squeezed out is called blood serum. Blood serum is essentially blood plasma with the clotting elements removed.

Many blood tests are actually conducted with the blood serum and not the blood cells. One test that checks for pregnancy is called the HCG test and can be performed with either urine or blood serum. The test checks for the presence of human chorionic gonadotropin (HCG), a hormone which is generally produced during pregnancy. In most cases a positive result means the patient is pregnant, though in rare instances a positive reading occurs in a non-pregnant patient with certain medical conditions.

Other blood serum tests involve measuring the different protein levels. Elevated or depressed levels of various proteins are indicative of medical conditions which may need further treatment. For example, an overall decrease in proteins may indicate malnutrition or other conditions which can be detrimental to the kidneys. An increase in alpha-1 globulin proteins can reveal the presence of an inflammatory disease such as rheumatoid arthritis.

Other common serum tests check cholesterol, triglyceride, lipoprotein and sugar or glucose levels. Cholesterol is a fatty substance in the blood which, while necessary, can lead to greater risk of heart disease and stroke if elevated. Elevated levels of triglycerides and lipoproteins are also risk indicators for stroke and heart disease. Elevated glucose levels indicate diabetes, while low glucose levels are responsible for a condition known as hypoglycemia. Blood serum tests are also performed to check thyroid and insulin levels.

Blood serum screening is continuing to expand, and new tests are being developed to help provide earlier detection of diseases such as Alzheimer’s and Parkinson’s. Though cures are not yet available for these conditions, early diagnosis can enable more effective treatment. Another innovative development is the use of a patient’s own blood serum to produce eye drops to treat severe dry eyes and other surface eye disorders that do not respond to synthetic eye drops. Because the drops are made from a person’s own serum, there is no danger of an allergic reaction.

Another serum blood test checks for certain enzymes in the blood which are normally only found in the liver. If these are present, it is an indication that some liver damage has occurred.