When should I consider referring a patient with macrocytic anaemia for specialist evaluation?

Consider referring a patient with macrocytic anaemia for specialist evaluation in the following situations:

• If the cause of macrocytic anaemia is unclear or the type of anaemia is in doubt, specialist haematological investigations may be required that cannot be performed in primary care, such as bone marrow examination or bleeding state investigations.
• If vitamin B12 or folate deficiency is suspected due to poor diet, consider referral to a dietician.
• If there is no improvement in haemoglobin or reticulocyte count within 7–10 days of starting vitamin B12 treatment, or if blood counts and mean cell volume have not normalised after 8 weeks of treatment, further specialist evaluation is warranted.
• If symptoms persist or worsen despite appropriate vitamin B12 or folate treatment, or if new symptoms develop that could be linked to vitamin B12 deficiency, consider specialist referral for further testing (e.g., serum methylmalonic acid or plasma homocysteine) and treatment adjustment.
• If macrocytic anaemia is associated with signs or symptoms suggestive of malignancy or other serious underlying conditions, urgent referral using a suspected cancer pathway should be considered.

These recommendations are based on expert opinion and NICE guidelines on macrocytic anaemias and vitamin B12 deficiency management in adults.

References: NICE CKS, NICE CKS, NICE NG239, NICE NG12