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The Haematinic panel of tests are often undertaken on routine Immunoassay and spectrophotometric platforms used by Medical Biochemistry Departments and are no longer confined to specialist Haematology Departments. This Programme covers the main parameters assayed by Biochemistry Departments.
Ferritin is used as an indicator of iron status. A ferritin of <30ug/L is indicative of iron deficiency, whilst an elevated level (>400 ug/L) is indicative of iron overloading such as haemosiderosis or haemochromatosis. Elevated ferritin values are also encountered in certain tumours: acute leukaemia, Hodgkins disease and carcinoma of the lung, colon, liver and prostate.
Investigation of folate deficiency may be indicated when nutritional, macrocytic or megaloblastic anaemias are suspected. Since a deficiency of either vitamin B12 or folate can cause megaloblastic anaemia, both tests are indicated in order to diagnose the aetiology of anaemia.
There is currently no standard test for measuring vitamin B12 deficiency. Guidelines for the diagnosis and treatment of cobalamin and folate disorders from the British Society for Haematology (Devalia et al. 2014) state that serum total vitamin B12 remains the first-line test for B12 deficiency because of its wide availability and low cost, but that it lacks the sensitivity and specificity needed for a robust diagnostic test. Deficiency can occur when there is not enough dietary intake of the vitamin, in malabsorption such as in gastric, pancreatic or intestinal diseases (including removal of all or part of the stomach or gastric bypass surgery), in HIV and in pernicious anaemia. The latter is an autoimmune disorder that results in inflammation and damage to the stomach lining, and loss of parietal cells, digestive enzymes and mucus. The parietal cells produce intrinsic factor, a protein needed for absorption of vitamin B12 in the gut. Vitamin B12 exists in 2 bound forms, bound to haptocorrin to form holohaptocorrin; or bound to transcobalamin to form holotranscobalamin (holoTC). As cells can only take up B12 in the holoTC form the measurement of holoTC is more reflective of vitamin B12 status than measuring total vitamin B12 or holohaptocorrin alone. The guidelines state that serum holoTC has the potential to be used as a first-line test and may reduce the number of indeterminate results, particularly in people over 65 years, in pregnant women, and in women taking oral contraceptives. Tests for holoTC are termed Active-B12 assays: NICE Medtech innovation briefing 40, Active B12 assay for diagnosing Vitamin B12 deficiency.
Iron (non-haem) measurements are used in the diagnosis and treatment of diseases such as iron deficiency anaemia, haemochromatosis and chronic renal disease and in the diagnosis of acute iron toxicity.
Total iron-binding capacity (TIBC) is a measurement of the maximum iron concentration that transferrin can bind. In iron-deficiency anaemia the TIBC is elevated and the transferrin saturation is lowered to 15 % or less. Low serum iron associated with low TIBC is characteristic of the anaemia of chronic disorders, malignant tumours, and infections.
Four liquid human serum samples are distributed monthly, with a minimum of 48 samples distributed over the year covering a wide clinically relevant range. The material is prepared from endogenous samples donated by polycythaemic, hemochromatosis, renal patients and healthy volunteers. The samples consist of a panel of 10 samples distributed on a number of occasions over that period which are used to assess both laboratory and method performance, including linearity, bias, within and between batch imprecision. Additional challenging samples spiked with iron traceable to NIST SRM #928 are distributed to assess the performance at mild and severely toxic levels.
Calculated parameters are also assessed such as TIBC and Transferrin Saturation. A separate programme is available for Homocysteine.
|Analyte||Approx. Range Covered|
|Ferritin||5 - 3500||µg/L|
|B12||120 - 850||ng/L|
|Active B12||0 - 300||pmol/L|
|Folate||1.2 - 24||µg/L|
|Iron||4 - 160||µmol/L|
|TIBC||27 - 90||µmol/L|
|UIBC||3 - 100||µmol/L|
|Transferrin||1.6 - 4||g/L|
|Transferrin Saturation||10 - 90||%|