Total protein test.
A total protein test measures the sum of different proteins present in the blood. Proteins are very important for the proper functioning of the body, be it in the form of enzymes, clotting factors, hormones etc. The two proteins that are majorly found in the blood are albumin and globulins.
Albumin is one of the abundant proteins found in blood. It maintains osmotic balance between the blood and tissues. It helps to keep the blood from leaking out of the blood vessels, also helps in tissue growth and repairing. Its level is tested to check the proper functioning of liver and kidney, to check if a person is consuming enough protein and to check for inflammation.
Globulin plays a very important role in immune system. This is tested to check if our body is able to fight infections and also to check for blood disorders like multiple myeloma.
The total protein test measures the total amount albumin and globulin present in our body. This test may be done as a part of routine health check-up or if a person experiences unexpected weight loss, fatigue, or the symptoms of a kidney or liver disease. Measurement of the total protein level and the ratio of albumin to globulin helps in detecting various kinds of health problems, including liver and kidney disease as well as nutritional deficiencies.
Purpose of doing this test
The total protein test is done to check the levels of proteins in the blood. Too high or too little amount of protein can reflect conditions including liver or kidney disease, infection, malnutrition, inflammation, and cancer.
Basic principle of test
The most common method used nowadays for estimating total protein is Biuret method. In this method, peptide bonds of protein react with cupric ions in an alkaline medium to form a blue-violet coloured complex. The coloured complex formed is directly proportional to the concentration of protein in blood/ serum sample and its absorbance is measured at 546 nm colorimetrically.
Take three test tubes and label them as ‘blank’, ‘standard’ and ‘test’. Add 1ml of given reagent in each test tube. Add 0.02 ml distilled water in ‘blank’ tube, 0.02 ml standard solution in ‘standard’ tube and 0.02 ml blood/serum sample in ‘test’ labelled tube. Mix the contents gently and incubate for 10 minutes at room temperature. Take the absorbance of test and standard against blank in colorimeter.
The total protein is calculated by dividing absorbance of test by absorbance of standard and multiplying it by the concentration of standard.
The total protein is in the range of 6 – 8.3 grams per decilitre (g/dL). This range varies slightly among laboratories. These ranges may also vary due to other factors such as: Age, gender, pregnancy.
Elevated levels of total protein may indicate: inflammation, dehydration, infections such as Hepatitis B or C or HIV, multiple myeloma. Low levels of total protein may indicate: bleeding, liver disorder, kidney disorder such as a glomerulonephritis, malnutrition, malabsorption conditions, extensive burns, inflammatory conditions. Normally the A/G (albumin to globulin) ratio is slightly higher than 1. If the ratio is low, it can suggest: autoimmune disease, multiple myeloma, cirrhosis, kidney disease. A high A/G ratio may indicate genetic deficiencies or leukaemia.