Where do patients stand when it comes to getting blood tests done? Can they request specific ones? What basic ones will a GP do? Can you ask for the ‘Rolls Royce’ of tests if you are worried you have undetected conditions, for example?

With some readers angered recently that blood tests weren’t done in the past that could have shown up risk factors for a condition like osteoporosis, we asked Irish College of General Practitioners (ICGP) chair of communications Dr Mark Murphy about blood tests and what is available.

“Unfortunately there is no ‘Rolls Royce’ suite of blood tests,” he says. “When it comes to preventative and screening activities (health checks), the most important thing is that a GP can only go on what the evidence tells us, so we can’t just start recommending multiple blood tests. That would be unprofessional behaviour.

“You can only act on what the evidence base would say and, unfortunately, the evidence is quite limited that general health checks are beneficial.

“This has been a controversial area over the past 10 years because a lot of private facilities would heavily market, for profit, a certain healthcare activity that might not have an evidence base.”

BASIC BLOOD TESTS

What, then, are the basic blood tests that GPs will order?

“Glucose and cholesterol – the two tests for cardiovascular disease. That’s it generally. We would recommend that people know roughly what these figures are from the age of 40 or earlier if there is a strong family history of cardiovascular illness.

“GPs usually start doing a blood count and kidney profile for patients at the age of 50 too. We certainly would recommend that the person gets their blood pressure checked at the age of 40 also or earlier if there is a strong family history of cardiovascular disease.”

If you have symptoms or specific conditions it’s different, of course, he says.

“For example, if you are diagnosed with osteoporosis, blood tests for calcium and parathyroid hormone could be done. But in relation to screening in general, there are thousands of different blood tests so where do you start and finish? Blood tests cost a lot of money and they may also harm people because there are false positives and false negatives and anxieties.

“Over-medicalisation is one of the biggest issues in the health system. It is probably the biggest health challenge facing Western health systems and it is important that we do not facilitate that over-diagnosis by doing a battery of blood tests that lack an evidence base.”

A case-by-case screening of high-risk groups is done, however, he says.

“Related to osteoporosis, for example, we would consider getting a DEXA scan done for post-menopausal women who have many risk factors for the condition, say women who smoke, may drink and be overweight, as that category of patient might be at risk of developing low bone density.”

I mention anger among readers I’ve come across who were diagnosed late with the condition known as haemochromatosis (excess iron in the blood). Would a simple one-off screening blood test not have shown up that they had the condition early on and avoided debilitating symptoms like chronic fatigue being experienced over many years?

“I can understand anyone’s frustration when they develop a condition and they think it might have been picked up sooner, but it’s not practical to screen everyone. It would be harmful for us to do a DEXA scan on every woman in the country, for example.”

NO MAGIC BULLET

He points out that the only State health screening programmes are for breast, cervical and bowel cancer.

“There is no magic bullet in terms of health checks. If you feel well, you are generally well and there isn’t a lot, I suppose, you should be doing in terms of getting a health check, but if you have a symptom then you should go to the GP immediately and get assessed.

“The most important thing is holistic factors like diet and exercise and reducing stress. That is, by a country mile, the most important thing you can do for your health.

“Obviously, participating in the three national screening programmes is important and after the age of 50 you can consider getting some fasting blood tests with your GP.

“If you have certain concerns or other risk factors, eg a strong family history of a condition like osteoporosis, you might be in that high-risk category and you might benefit from other types of screening.”

CAN A PATIENT REQUEST A

SPECIFIC BLOOD TEST?

If a patient requests a particular blood test, does a GP have to do it?

“That’s a different debate. If a patient wants an MRI, for example, and their doctor doesn’t think there is a need for it, that’s an ethical issue about the patient’s autonomy and the fair distribution of resources in society, so cognisance of all those things determines the discussion. It has to be taken on a case-by-case basis. If the patient wants something, they often do get it once the pros and cons of the process are discussed.

“There are limitations, though. There are some blood tests that might cost thousands of euros that GPs mightn’t have access to, but if the patient wants their vitamin D checked, for instance, that can happen.

“What I’d say is, have a conversation with your GP about the pros and cons.” CL

>> Blood facts

WHERE BLOOD IS TESTED

After the vials containing your blood samples are filled, they are sent to a hospital laboratory to be processed.

The tubes are colour coded for particular tests and different laboratories. Samples may be sent to different departments in the laboratory depending on what the GP wants the blood tested for. It could go to the haematology department (for full blood count), to the biochemistry department (glucose test), immunology department (detecting auto immune diseases like rheumatoid arthritis) or endocrinology department (for testing kidney and hormone levels/thyroid).

Results are usually back within a week and the patient is notified.

WHAT IS BLOOD MADE UP OF?

Blood cells are divided into three main types – red cells, white cells and platelets. Blood also includes plasma. One drop of blood contains about five million red cells. Millions of blood cells are made in the bone marrow by blood stem cells.

Red cells contain a chemical called haemoglobin, which binds to oxygen and takes oxygen from the lungs to all parts of the body.

White cells defend against infection. Platelets help the blood to clot if we cut ourselves. Plasma is mainly water but also contains many proteins and other chemicals such as hormones, antibodies, enzymes, glucose, fat particles and salts.

You need a healthy bone marrow and good supply of nutrients from food, including iron and vitamins, in order to constantly make blood cells.

WHAT ARE BLOOD TESTS FOR?

Blood tests are done to assess your general state of health, confirm the presence of infection and see how well organs like the liver and kidneys are functioning.