Blood tests Q&As

What is the DR70 test? Is it reliable? Is it available in the UK?

The DR70 test is a simple blood test which, it is claimed, can detect at least thirteen different types of cancer (including breast, bowel and lung cancers) when they are at a very early stage, often before they will cause symptoms or show up on any other test.

Companies marketing the test therefore suggest that healthy people could use it as a screening test, to see whether or not they might have a cancer and people who have had cancer in the past could use it to check that there was no recurrence of their illness.

This all sounds very exciting but there are at least three problems:

• the scientific studies that have been done on the DR70 test are still very few and the information very limited. There is a lot more to be done to be sure how useful and reliable it is.
  
• the scientific tests that have been done do show that the test can detect some cancers at an early stage but there are a significant number of both false positive and false negative results (this means that the test may suggest someone has got a cancer when they haven't or it may miss a cancer when it is actually present).
  
• if it is positive the test still does not tell what type of cancer may be present, so it can't say whether there is a bowel or breast or lung or other cancer, just simply it says there may be a cancer somewhere.

All this means that the test could cause a great deal of anxiety with little or no real benefit. For example, someone could have a positive test and then have literally months of further blood tests, scans, x-rays etc to try and find a cancer. If all these were negative they still would not know whether the original DR70 test had been wrong or whether they did really have a cancer somewhere which would show up in the future but was too small to show up on the normal tests.

This means that anyone who is considering having the test really should be carefully counselled before and after so that they know its limitations and what the results will really mean for them and how those results might affect their life.

At the present time the British Government's Medical Devices Agency has decided 'the available evidence is of insufficient quality and quantity to come to any firm conclusions regarding the likely usefulness of DR70 as a screening test. As a consequence of this the DR70 test is not available on the NHS at the present time but there are at least two companies who market the test commercially in the UK.

When doctors do my blood tests they mention haemoglobin. What is haemogloblin? What should my haemoglobin level be?

Haemoglobin is the coloured pigment inside red blood cells that carries oxygen round the body.

Haemoglobin levels in the blood are measured in grammes per 100 millilitres, which is abbreviated to g/dl. The normal range of haemoglobin for a man is 13.5 to 17.5 g/dl and for a woman is 11.5 to 15.5 g/dl. Anything less than these numbers is called anaemia.

As the haemoglobin level starts to fall, the body is very good at compensating for the drop in red cells. The heart will beat faster and more forcefully and the lungs increase the amount of air they move each minute to increase the amount of oxygen they deliver to the blood. The body also gets better at taking up oxygen into the red cells and releasing it where it is needed.

This is why we can often cope with slightly lower than normal haemoglobin levels, especially if they develop gradually. But when the level drops too low for us, we start to feel tired, breathless and may start to run into problems with too little oxygen getting to important organs like the heart and brain. This can cause palpitations, angina (chest pains), headache or dizzy spells.

Not everyone will get symptoms at the same level. Some elderly people, whose heart and lungs are less good at compensating for their anaemia, may develop severe symptoms at around a haemoglobin of 9 to 11g/dl. If someone has narrowing of the blood vessels to the heart, they too may get angina at a haemoglobin of this level. Some young fit patients may be to manage with a much lower haemoglobin and only develop symptoms when their haemoglobin falls to around 6g/dl. However recent studies have shown that most people feel less tired if their haemoglobin is above 12g/dl. There is also some evidence to suggest that people may respond better to chemotherapy if their haemoglobin is at higher levels. As a result many doctors nowadays tend to treat a moderately low haemoglobin (below 11 or 12), particularly if someone is feeling weary.

To some extent it is a matter of finding the haemoglobin where you feel most comfortable but severe anaemia is not safe and always needs to be treated. Often this will involve a simple blood transfusion which can rapidly correct the problem. It is also possible to correct your haemoglobin by giving a chemical called Erythropoietin. However this takes a long time to work, is not effective in everyone and requires regular injections. It is also very expensive.