Blood Test

March 14 23:17 2019 Print This Article

Blood Test is an important means of diagnosing disorders of organs and systems of the body. Blood tests also provide information on the condition of the blood cells and plasma (the liquid part of blood). Your doctor or a nurse can collect a blood sample and -apart from the slight discomfort of the needle puncture – this is quick and painless. The sample is usually taken from a vein in the bend of the elbow or on the back of the hand. In babies, the scalp veins may be used. Blood is collected from an artery only when blood gases need to be measured. For most tests, blood can be collected at any time of the day. However some tests require blood to be sampled at particular times of the day. after a 12-hour fast or at a set interval after a measured amount of food has been eaten.

The majority of blood analyses are carried out on serum, the liquid left after the blood in the sample has dotted and the blood cells and dot have been separated from it by spinning the sample in a centrifuge. If the blood cells or plasma are to be examined, some of the sample is placed in a special tube containing a chemical that prevents the blood from dotting. This is called a whole blood sample

The blood may be analysed by several different laboratories. Haematology deals with the blood cells, blood groups and dotting functions. Bio-chemistry measures the concentration of the many substances dissolved in the serum. Specialised laboratories.measure hormones and antibodies in serum. Sometimes blood may be sent to MICROBIOLOGY laboratories to test for the presence of bacteria or viruses.

Many of the common blood tests are now performed by computerised machines called autoanalysers, and results are available within a few hours of samples reaching the laboratory. Unusual or highly specialised tests are performed in batches once or twice per week, and results may take longer to obtain.

What the risks are?

  • Infection.
  • Excessive bleeding.
  • Blood accumulating under the skin.
  • Fainting or feeling lightheaded.

Why it is done?

Blood glucose tests are done to:

  • Check for gestational diabetes.
  • Determine if an abnormally low blood sugar level is present. A test to measure blood levels of a protein called C-peptide may be done along with a blood glucose test to determine the cause of hypoglycemia.
  • Monitor treatment of diabetes.

What affects the test?

  • Smoking.
  • Drinking alcohol.
  • Caffeine.
  • Certine medication, such as birth control pills.
  • Eating or drinking less than 8 hours before a fasting blood test or less than 2 hours before a 2-hour postprandial test.
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