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Laboratory Test Descriptions
Our handy guide to the abbreviations found on common blood tests
Interpreting common blood tests
This is meant as a guide to help you interpret some common laboratory results. Our GP will comment on your actual results in writing at the time so you understand which results are within normal limits and some that may require further investigation or attention. Further investigation or interpretation will require a minimum 15 minute consultation (telephone consultations available) at our GP consultation rates.
Haematology
| Haemoglobin |
This indicates the presence or not of Anaemia |
| RBC |
This shows the number of red cells. |
| MCV |
This shows the red cell size: Large red cells may indicate deficiency of B12 or Folate or alcohol damage, small red cells may indicate hereditary blood disorders e.g. Thalassaemia or sickle cell disease as well as iron deficiency, if present. |
| RDW |
This shows if several populations or red cells are present e.g. in blood regeneration after bleeding. |
| Platelets |
This is the number of clotting cells. It is also increased in some inflammatory diseases. |
| WBC |
These are the immune cells. |
| Neutrophils |
These are responsible for bacterial immunity. Neutrophil numbers rise in bacterial infection and usually drop in viral infections. |
| Lymphocytes |
These are responsible for vial immunity. They rise in viral illness. May drop for the same cause. |
| Monocytes |
Increased in Glandular Fever (Infectiois Monnucleosis) and other similar infections. |
| Eosinophils |
These cells are increased in some intestinal parasites infections and more commonly in allergies e.g. Hayfever. |
| ESR |
Erythrocte Sedimentation Rate: This indicates recent inflammation: It rises in infection, cancers, auto-immune diseases (e.g. SLE) and in pregnancy. It also rises normally with age. |
Biochemistry
| Sodium |
This measures salt in the blood: It is raised in dehydration and after excessibe salt consumption. |
| Potassium |
This rises in some kidney diseases. It may fall if diuretics (Fluid tablets) are taken. However; it will rise falsely if the red cells are damaged by delay in processing by the lab, if this is the case, the glucose usually drops as a result of red cell metabolism. |
| Bicarbonate |
This measures acid/base levels (ph). Many diseases e.g. infections and poisoning (e.g hangover) can cause acidosis i.e. low bicarbonate levels |
| Urea, Creatinine |
These measure kidney function. |
| eGFR |
i.e. estimated Glomerular Filtration rate. This measures kidney function, taking in account creatine, age gender and ethnicity. The ideal is over 91, danger is under 60 ml/min |
| Glucose (Fstg) |
This measures blood glucose, as with diabetes. Ideally measured fasting. |
| Calcium, Corrected Calc. |
This corrects the calcium level, taking serum albumin in to account. |
| Uric Acid |
This measures gout risk. |
Liver Function Tests
| Total Protein, Albumin, Globulin |
These measure the liver's ability to manufacture proteins. |
| Total Bilirubin |
This rises if fasting, in Gilberts Syndrome. It may show liver or red cell damage, if elevated. |
| Alkaline Phosphatase |
This is low in Zinc deficiency, raised in Gall stone obstruction and in some bone injuries or diseases. |
| AST, ALT |
These measure liver damage. |
| Gamma GT |
This shows the presence of fatty liver, typically from alcohol and diabetes or both. "Low for London Alcohol effect" means what commonly passes for normal alcohol consumption in London is regarded as excessive elsewhere. |
| LDH |
This measures liver damage |
| CK |
If elevated, this indicates muscle damage e.g. exercise effect, in whish case it may be normal for that patient. If low-normalit usually indicates a sedentary lifestyle. However; athletes performing unchaning daily exercise e.g. running may have normal CK levels unless they vary their training. |
Iron Stores
| Serum Iron, UIBC, Fe Binding Sat%, Ferritin |
These are the iron stores. However; Ferritin is also an inflammation marker and must be interpreted in light of other inflammation markers especially CRP. Very high Ferritin usually means iron overload e.g. Haemochromatosis |
Lipids
| Cholesterol |
Cholesterol measurement alone is unhelpful. A very high cholesterol e.g. over 8 ususally means another problem e.g. low thyroid or kidney disease. |
| Triglycerides |
This is affected by fasting and diabetes. |
| HDL |
This is the detergent-like protective factor which balances total cholesterol. It rises after sociable consumption of alcohol and with exercise and drops with excessive alcohol and without exercise. It is a good lifestyle marker. |
| LDL |
This is the bad cholesterol |
| HDL/Chol Ratio |
This is the ratio of protective to total cholesterol and should be over 25%. |
| Homocysteine |
This is a risk factor especially for vascular and neurological diseases. It is adversely affected by transport delay to the lab, lack of chilling in transit and non fasting status. Non fasting readings are typically 25% higher than true fasting values. |
| CRP (Cardiac) |
This measures current inflammation. A reading over 3 suggests high risk of heart attack. |
Endocrine
| TSH |
This is the signal from the Pituitary Gland to the Thyroid Gland to produce Thyroid Hormone. |
| FT4 |
This is the Hormone response from the Thyroid gland. |
| Free T3 |
This is the activated hormone converted in the general body tissues. Conversion block from FT4 to FT3 usually results from overwhelming stress. (Rarely, from Selenium deficiency). Stress is a potent common cause of this. |
Prostate Specific Antigen (PSA)
| PSA |
This is a function of prostate size and activity, increasing with benign prostatic enlargement, infection and cancer. |
| PSA FREE/TOTAL Ratio |
If the PSA is eqivocal, an abnormal free/total PSA ratio suggests re-testing earlier rather than later. |