What Is Blood Serum?

Most blood tests are conducted with blood serum, not blood cells.
Plasma transports red and white blood cells throughout in the body.
Pouches of blood.
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  • Written By: Brenda Scott
  • Edited By: Bronwyn Harris
  • Last Modified Date: 19 April 2014
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Blood plasma is the clear, yellowish liquid in blood that 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 that is squeezed out is called blood serum. Serum is essentially blood plasma with the clotting elements removed.

Many blood tests are actually conducted with the blood serum, not the blood cells. Some types of pregnancy tests are specifically performed on this part of the blood. The test checks for the presence of human chorionic gonadotropin (HCG), a hormone that is produced during pregnancy. In most cases, a positive result means the patient is pregnant.

Other serum blood tests involve measuring the different protein levels. Elevated or depressed levels of various proteins are indicative of medical conditions that may need further treatment. For example, an overall decrease in proteins may indicate malnutrition or other conditions that 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 may allow for more effective treatment. Another innovative development is the use of a patient’s own serum to produce eye drops to treat severe dry eyes and other surface eye disorders that do not respond to synthetic medications. 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 that are normally only found in the liver. If these are present, it is an indication that some liver damage has occurred.


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Post 3

@anamur-- You will need to give separate samples for each test that is required.

Both blood sugar testing and thyroid function testing are considered endocrine tests and blood serum is used for both. However, since the serum is being checked for different substances, there needs to be separate samples that can be centrifuged.

A centrifuge is the equipment that is used to separate blood plasma from the serum. The blood sample is put inside and it rotates super fast causing these two components of blood to separate. Then they check the anti-coagulated blood serum for different substances, like glucose or hormones.

Post 2

@anamur-- My close friend uses blood serum eye drops and speaks very highly of it. As far as I know, they take some blood concentration from the individual, separate the blood serum and then use it to make eye drops. It's supposed to be the closes thing available to natural tears.

My friend has it processed at a compounding pharmacy near her. It's apparently kind of expensive but she says it's worth it. She has had severe dry eye and an issue with her cornea. She says the eye drops have helped her a lot. Her eyes are not as irritated, dry and painful as they used to be.

I think it sounds kind of odd, but if it helps, then why not use it? Your mom can ask her doctor if this is available in her area because not every lab has the equipment to prepare it.

Post 1

I'm scheduled to have a blood serum test next week to check my thyroid as well as blood sugar levels. I've been experiencing fatigue, weight gain, increased thirst and cravings recently. I have diabetes in my family and I have symptoms of a low functioning thyroid so my doctor wants to check both.

I'm curious, is one sample of blood serum enough for both tests or will I have to give multiple ones? I'm a little scared because I can't stand the sight of blood and hate giving samples for testing.

And does anyone know more about blood serum eye drops? My mom has dry eyes and uses synthetic eye drops regularly. I had never heard about eye drops made from blood serum before.

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