Cardiovascular disease (heart attack, stroke and peripheral vascular disease), usually shortened to CVD, kills more people than cancer. More women will have a heart attack than will die of breast cancer. Some of the risks for CVD are well known, such as smoking and hypertension. So where do diagnostic tests fit in? And what are diagnostic tests anyway? Diagnostic tests are "blood tests", an often unrecognised but essential part of all stages of healthcare. These tests are becoming faster and smarter. There are now tests, which used to take a week that can be done in 20 minutes. New tests are available which can tell us if we are likely to have a heart attack, how bad an attack was and the long-term outcome.

Eating asparagus as a delicacy goes back to Roman times. In 50 per cent of people there is the asparagus effect, with the production of particularly odoriferous urine. The reason for this is genetic. These people have a particular gene, which results in the metabolism of asparagusic acid and production of chemicals such as methanethiol and dimethyl sulphide in the urine. As with asparagus, so with cardiovascular disease. There are genetic factors in the risks of having a heart attack, so pick your parents with great care! The Human Genome project and the potential for human gene mapping have been rightly highlighted as a major breakthrough. The role of genetic testing for improving healthcare has been recognised as a priority for the NHS. Modern laboratories are making the first steps in using specific genetic markers for individual conditions. Commercially available (rather than research based) tests are starting to become available. This is the first faltering step. The future possibilities are that we will be able to identify individuals with greater susceptibility to cardiac disease for earlier prevention and treatment. This will mean better use of scarce NHS resources.

Red wine consumption apparently reduces the risks of heart attack, due to its antioxidant content. Wine consumption is said to be the basis of the "French paradox", an apparently lower rate of CVD in France. A range of diagnostic tests is available which can be used to assess the risks of developing CVD. Some are well known, such as measurement of cholesterol. What is less well known is that cholesterol is divided into fractions, LDL (bad cholesterol) and HDL (good cholesterol). It is not just the amount of cholesterol but the ratio between the total cholesterol and HDL, which allows assessment of risk. The higher the HDL, the less the risk of heart attack. Exercise and alcohol (in moderation) raise HDL. Modern drugs, the HMG-CoA reductase inhibitors ("statins") can safely and effectively reduce blood cholesterol. This will reduce the risk of heart attack by about one third. How well an individual has responded requires continued monitoring by measurement of blood cholesterol.

Blood tests can check if there are side effects of treatment. And there are other blood tests to detect a high risk of heart disease. Homocysteine, when high, indicates a greater risk as does a high Lp(a), a molecule made up of LDL joined to apoprotein (a). C reactive protein (CRP) is traditionally used to detect infections and inflammation. When slightly elevated in "normal" people it identifies those who may benefit more from treatment with statins, especially if their cholesterol is only slightly raised. If you have had a heart attack, two more blood tests, cardiac troponin and B-type natiuretic peptide will tell you how bad it was, what the doctor needs to do next (which drugs will work best, if you need bypass or angioplasty) and if you have heart failure.

Canapétain calories. A moment of pleasure on the lips, a lifetime of effort on the hips. As we eat more and exercise less, more people are developing diabetes. Why are we worried about diabetes? Because people who have diabetes have a similar risk of heart attack to those people who have already had a coronary. Laboratory tests are the only way to diagnose and monitor diabetes risk. Diagnosis depends initially on measurement of the amount of glucose in the blood. Monitoring the severity of disease is by measurement of glycosylated haemoglobin. This is a fraction of the haemoglobin (the oxygen carrying compound in the blood) which has a glucose molecule attached to one end. The higher the overall level of blood glucose has been, the higher is the glycosylated haemoglobin. And the higher the glycosylated haemoglobin, the greater the risk of the complications of diabetes, blindness, kidney failure, amputation and heart attack. This has been shown in two major clinical studies, one in the UK (the UK-PDMS study) and one in the USA (the DCCT study). So we know it works - evidence based diagnostic testing. Good diabetic control means fewer complications, which means less cost to society in the short and long term. Do you think we should be doing fewer diagnostic tests? Consider your ABC.

Dr Paul Collinson is a Consultant Chemical Pathologist at St George's Hospital, London