Blood tests are performed at the Medical Centre by the nurses and phlebotomists (a person who has been trained to take blood samples). When you see the Doctor, if a blood test is required, you will be given a pink form to hand in to Reception. This form will tell the Receptionists what tests you need and how soon the tests need to be done. You will usually be given an appointment with the nurse to have the blood taken. Don't worry if the Doctor has advised numerous tests because they can all be taken in one go, without having to have repeated needles.

The following tests are commonly performed.

FBC    ESR    U&E   LFT     Glucose    TFT     Monospot    INR     Lipids    HbA1c

FBC
This means "Full Blood Count". This test can measure a number of different elements in the blood. It can measure your "haemoglobin". This is the chemical that gives your blood its red colour. If the haemoglobin is low, you are anaemic. There are many different types of anaemia - not all are responsive to iron treatment, so your Doctor will need to determine the exact type of anaemia and why you are anaemic. This test also looks at the size of the red blood cells. If they are large it can be a sign that you drink alcohol regularly, or have thyroid disease or vitamin deficiency (amongst other things). The FBC also looks at the white blood cells. These are the cells that fight off infection. The white blood cells may be increased when you are suffering from an illness.

ESR
This means "Erythrocyte Sedimentation Rate". When you are ill, whether it is arthritis, a sore throat, or virtually any disease, the cells in your blood become "sticky". We can measure this "stickiness" by filling a tall glass column with blood and measuring how long it takes for the cells to sink down the column. The stickier they are, the longer it takes for them to sink and the higher the "ESR" figure is. This test can be difficult to interpret because it is normal for the ESR to increase with age and, if it is high, it gives no indication as to the cause. It is often used to monitor the response to treatment of arthritis.

U&E
This means "Urea and electrolytes". This test measures the functioning of your kidneys and the level of various salts in the body. The salts can become low if you take a diuretic ("water tablet") and we usually perform this test on an annual basis on patients who are taking this medication. This test may also highlight dehydration after diarrhoeal illness or vomiting. It may also give us clues as to how well your kidneys are working.

LFT
This means "Liver Function Test". This test measures various chemicals involved in liver and gall bladder disease, as well as bone metabolism. It may give clues to indicate gall stones, whether you drink too much alcohol, or whether you have a number of different bone diseases. It may also reveal jaundice (this is the condition where people develop a yellow appearance due to excessive amounts of a chemical called "Bilirubin"). This test can become abnormal if you take certain types of medication.

Glucose
This is a test of the level of a sugar called "glucose" in the blood. If the level of glucose in the blood is high, it can be a sign of diabetes. However, if you have just had food or a sweet drink, the level may go up. For this reason, we usually advise having this test on an empty stomach (i.e. having not had anything to eat since the evening before). The symptoms of diabetes may include thirst, passing lots of urine, weight loss and tiredness. Diabetes that comes on in middle age can be hereditary. You will be at a higher risk of developing the disease if you are middle aged, overweight and have blood relatives with diabetes that started in middle age.

HbA1c
This tests forms one of the battery of standard tests performed before Diabetic Clinic. It tells us the average blood glucose in the preceding weeks before the blood was taken. It helps to tell us if Diabetics really have been sticking to their diet!
 

TFT
This means "Thyroid funtion test". This measures the activity of the thyroid gland and the response to thyroid hormone replacement in people who are deficient in the hormone. The thyroid gland lies at the front of the neck. It may become "over" or "under" active. If you have an underactive gland, you will need to take thyroid hormone replacement - but the dose required will be different for different people. This test tells us whether the dose needs to be changed but we cannot tell until you have been taking a particular dose of Thyroxine (thyroid hormone) for at least 6 weeks.

Monospot
This test has a number of names including the "Paul Burnell" test. It is a test to see if you have contracted glandular fever. Glandular fever is due to a virus. It commonly affects teenagers and young people. Symptoms include a really sore throat and profound tiredness. Sufferers commonly report having to go to bed to sleep in the middle of the day. It may last for months before getting better.

INR
This stands for "International Normalised Ratio". It is a test of how "thin" or "thick" the blood is. In other words, how easy it is to clot. The normal value is "1". This means normal clotting. Some people need to take a medicine called "Warfarin" to make the blood thin and stop it from clotting. If you take Warfarin, the INR number goes up. The higher the number, the thinner the blood and the less likely it is to clot. The amount of Warfarin needed to thin the blood in different people varies. Some people need a lot, others less. The Doctor will want to keep the INR figure between certain levels depending on why the blood needs to be prevented from clotting. From the INR figure, the doctor can work out how much Warfarin you need.

Lipids
This is a check of the blood fats. There are 2 main types of fat that we measure and they are called "Cholesterol" and "Triglycerides". With time, these fats may become deposited on the walls of the blood vessels so that they become narrower. It's a bit like the build up of limescale on your kettle! Unfortunately, this process can lead to many diseases including heart attacks, angina and strokes. If the level of lipids are high, this process may occur at an early age. The test is performed on an empty stomach. The Doctor or nurse will be able to advise you whether you need to follow a diet or start tablets to lower the blood lipids if they are high. See also "What's my cholesterol - is it OK?" or view the Pencoed Medical Centre Low Fat Diet

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