Blood tests

Blood tests patients might expect from GPs and what they mean

Our thanks go to GP Dr Goodman, the parent of a 12-year-old boy with severe ME, for providing this information

The following tests may be carried out by GPs or paediatricians (some GPs are reluctant to do blood tests on a young child and will refer to the paediatrician) because it is important to rule out other conditions before diagnosing someone with ME.  There is no diagnostic test for ME.

FBC (full blood count) - this is to exclude anaemia, leukaemia and other blood disorders.  The haemoglobin level is low in anaemia.  The while cell count (involved in fighting infection) may be raised in a recent bacterial infection but low in a recent viral infection.  Otherwise you would expect the result to be normal in ME.

Paul-Bunnell (or IM) test - this is another test done on the same tube of blood and looks for recent Glandular Fever infections (infectious mononucleosis), which commonly causes post-viral fatigue and may sometimes lead to ME.

CRP (C-reactive protein), PV (plasma viscosity) and ESR (erythrocyte sedimentation rate) - are all non-specific markers for inflammation or infection.  Inflammation could for instance be due to inflammatory arthritis, inflammatory bowel disease or rarely malignancy.  Infection could be bacterial or viral.  Unless one of these was a precipitant for ME, in general you would expect these to be normal.

U&E (urea and electrolytes) and creatinine - these are measures of kidney function.  The urea and creatinine levels are raised in kidney disease.  There may be minor abnormalities in these results with other problems such as dehydration or Addison's disease (a deficiency of the hormone cortisol), and a few rare syndromes that alter potassium levels.  You would expect results to be normal in ME.  Blood or urine glucose is raised in diabetes - a vital illness to exclude in someone presenting with fatigue.  Pathological hypoglycaemia (very low blood glucose) is rare.

Urinalysis - is a 'dipstick' urine test.  It checks for protein (may indicate infection or kidney disease), glucose (which could indicate diabetes), ketone (raised with vomiting, rapid weight loss or untreated diabetes).

LFT (liver function tests) - this is a measure of enzymes produced by the liver, and bilirubin which is processed by the liver.  If any of these are raised this could indicate hepatitis (including Glandular Fever) or other liver disease.  A small percentage of the population normally has a slightly raised bilirubin, which can go up during infection but does not indicate any liver disease.  This is called Gilbert's disease.

TFT (thyroid function tests) - this demonstrates normal, over or under activity of the thyroid gland.

CK (creatine kinase) - a muscle enzyme.  It may be raised with some muscle disorders and commonly after injury or bruising.

Endomysial antibody - this is a screening test for coeliac disease (affects 1:200 population) which can present with fatigue.  The treatment of confirmed coeliac disease is lifelong complete avoidance of food containing gluten (a protein found in wheat, rye, barley and oats).

Viral titres - indicates past or recent infection of various viral infections.  Titres of some 'atypical' organisms may also be measured, eg. mycoplasma or Borrelia (Lyme disease).

RhF (rheumatoid factor), ANA (antinuclear antibody) and autoantibodies - a battery of tests that look for conditions such as rheumatoid disease, SLE and other auto-immune diseases, where the body erroneously attacks itself.  These tests should all be normal in ME.

Height and weight - obviously not a blood test, but an important check, especially in children.

General examination - I would expect to check the chest, heart, abdomen, throat, lymph glands, blood pressure, pulse and temperature.

If the patient is referred on to a specialist there are other tests that may also be considered such as CAT and MRI scans (both radiology techniques that look at the body in slices, like salami), ECG (heart tracings) and more complicated blood tests for hormones, etc.  However, these would only refer to a minority of patients.

Article last edited on Thursday 12th August 2010                          Printable Version