Megaloblastic Anaemia Investigations PDF

Megaloblastic anaemia: investigations Gavin Knight  Learning Objectives Upon completion of this session, you should be able to: 1) Critically discuss the range of tests available for the investigation of cobalamin or folate deficiency 2) Identify the strengths and limitations of the tests...

Megaloblastic anaemia: investigations Gavin Knight  Learning Objectives Upon completion of this session, you should be able to: 1) Critically discuss the range of tests available for the investigation of cobalamin or folate deficiency 2) Identify the strengths and limitations of the tests involved in establishing a diagnosis of cobalamin/folate deficiency  MORPHOLOGY FBC and blood films lack sensitivity in early deficiency Oval macrocytosis and >3% hypersegmented neutrophils (>6 lobes) are indicative of megaloblastic anaemia Other causes of macrocytosis need to be considered http://hematologyoutlines.com/atlas_topics/137.html https://imagebank.hematology.org/image/63103/megaloblastic-anemia  COBALAMIN AND FOLATE INVESTIGATIONS Serum cobalamin measures both: Inactive forms: transcobalamin I and holohaptocorrin bound cobalamin Active form: holotranscobalamin Total Homocysteine is increased in both cobalamin and folate deficiency, BUT abnormalities can precede symptoms so it can be a useful measurement Plasma Methylmalonic acid is increased in cobalamin deficiency only, but is also affected by renal disease, small bowel bacterial overgrowth and haemoconcentration Serum folate can be measured to diagnose deficiency but there are limitations False positive and false negative folate results can be problematic. Cobalamin deficiency complicates folate interpretation COBALAMIN AND FOLATE INVESTIGATIONS Cobalamin only Folate Cobalamin  Summary Cobalamin and folate are often measured together in response to clinical suspicion Grey areas between normal and abnormal can be difficult to resolve Complex interplay between biochemistry can create interpretive difficulties Results should always be considered with clinical context in mind Treatment should be administered as per British National Formulary (BNF) guidance