HbA1c (glycosylated haemoglobin) and vitamin C

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Some of the factors that influence HbA1c and its measurement

  • 1. Erythropoiesis
    • Increased HbA1c: iron deficiency, vitamin B12 deficiency, decreased erythropoiesis

    • Decreased HbA1c: administration of erythropoietin, iron, vitamin B12, reticulocytosis, chronic liver disease

  • 2. Altered Haemoglobin
    • Genetic or chemical alterations in haemoglobin: haemoglobinopathies, HbF, methaemoglobin, may increase or decrease HbA1c

  • 3. Glycation
    • Increased HbA1c: alcoholism, chronic renal failure, decreased intraerythrocyte pH.
    • Decreased HbA1c: aspirin, vitamin C and E, certain haemoglobinopathies, increased intra-erythrocyte pH
    • Variable HbA1c: genetic determinants

  • 4. Erythrocyte destruction
    • Increased HbA1c: increased erythrocyte life span: Splenectomy

    • Decreased HbA1c: decreased erythrocyte life span: haemoglobinopathies, splenomegaly, rheumatoid arthritis or drugs such as antiretrovirals, ribavirin and dapsone

  • 5. Assays
    • Increased HbA1c: hyperbilirubinaemia, carbamylated haemoglobin, alcoholism, large doses of aspirin, chronic opiate use

    • Variable HbA1c: haemoglobinopathies

    • Decreased HbA1c: hypertriglyceridaemia

* Some of the above interfering factors are 'invisible' in certain of the available assays

Reference:

Last edited 03/2021 and last reviewed 05/2021

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