Which blood tests are included in our healthscreens? Dr Johnson explains.

Broadly, ten systems or functions are examined, directly or indirectly.

Blood count – this is a measure of red and white blood cell health. A normal red cell appearance, size and shape tell us the likelihood of certain mineral or vitamin deficiencies leading to forms of anaemia (iron, vitamin B12 and folate) is low, and that there is no underlying blood cell disease such as leukaemia.

Electrolyte balance is important, and imbalance in any of those tested can imply simple dehydration or a more complex metabolic disturbance, or even side effects of prescribed medication.

Kidney function can be accurately measured by looking at the concentration of waste products in the blood – the more there are, the less efficient the kidneys are functioning. Electrolyte imbalance can also give some insight into kidney function.

The liver (the body’s factory and detox machine) releases a number of enzymes and bile into the blood when it is struggling (for example if inflamed with hepatitis). Again, medication can lead to liver changes and sometimes apparently remote conditions can affect liver function (distant spread from malignancy would be an example).

Calcium levels can give us an insight into bone health and can also be affected indirectly by other conditions, including malignant disease.

Uric acid testing is straightforward – high levels indicate gout, a fairly common cause of painful joints. Uric acid can be elevated by some medication too, and can rise as a result of disease elsewhere.

Likewise glucose (with HbA1c) testing is simple in its objective – is diabetes present? Above a threshold it is, and below that level it is not.

Testing lipids is a useful way of predicting, at least in part, an individual’s risk of developing heart disease or other circulatory disorders. Knowledge of a full fasting profile is more useful as the balance of the component parts is important. It is important to stress though that having a ‘normal’ cholesterol is no guarantee of cardiovascular health – a far bigger risk faces those who smoke or have uncontrolled high blood pressure or diabetes.

Iron studies form part of the comprehensive profile – iron deficiency may exist before it is demonstrable in the blood as anaemia. And Vitamin deficiencies (B12, Folate, Vitamin D).

With the silver and gold editions, more tests are included - including the Ovarian and Prostate cancer markers (Ca125 and PSA), more detailed Hormone analyses, and Cortisol levels.

Finally, thyroid disease is an under diagnosed problem which may present in an unobvious way – with fatigue or weight gain for example. Maybe 10% of the population have an unrecognised thyroid disorder.

It may just interest you to know what is happening in your blood or you may have subtle but real concerns that something is amiss. Blood testing is relatively inexpensive, safe and informative – and as long as the limitations of such investigation are known, and that advice given is always within the context of any symptoms and signs present – a Comprehensive Blood Test can offer a helpful of insight into your state of health.