Each week we will aim to bring out a concise email that provides 4-5 key pieces of information addressing a specific issue in clinical therapeutics. This week:
Interpreting red blood cell morphology
The red blood cell morphology can provide important information that can be used in delivery a high quality medication review.
Normocytic, normochromic anaemia (low Hb, normal MCV, MCH) is most suggestive of anaemia of chronic disease, including chronic renal disease. A differential diagnosis is recent significant blood loss, especially if the Hb has recently been normal).
- Anaemia accompanied by leucopaenia (low WCC) and thrombocytopaenia can be associated with drug-induced pancytopaenia. Other possible causes include myelodysplasia or malignant infiltration in disease processes such as disseminated carcinoma or multiple myeloma
- Microcytosis +/- low Hb is most commonly caused by iron deficiency. In most cases, dietary deficiency is unlikely, the most likely cause is chronic blood loss, usually vi the GI tract. Look for possibly iatrogenic contributors such as anticoagulants, aspirin, NSAIDs +/- in combination with SSRIs
- Iron studies may be required if microcytic anaemia suggests the possibility of iron deficiency, and a test to detect faecal occult blood loss (e.g. Haemoccult™) may also be required.
- Macrocytic anaemia is often associated with vitamin B12 deficiency – given the potentially devastating consequences of B12 deficiency, unless a recent result is available to rule out a low serum concentration of B12, this test is strongly recommended. Folate deficiency is also associated macrocytic anaemia, and this investigation may also be required. Also associated with macrocytosis is chronic alcohol abuse.
Please consider these issues when preparing RMMR reports or education sessions. Contributions of content or suggested topics are welcome and should be sent directly to firstname.lastname@example.org