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Phaeochromocytoma Alpha Block Haemodilution — FRCA Final MCQ

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ModerateGeneral AnaesthesiaPhaeochromocytoma Alpha Block HaemodilutionFRCA Final

A 60-year-old man (ASA III) with phaeochromocytoma has been alpha-blocked with phenoxybenzamine for 3 weeks. His haematocrit has dropped from 48% to 38% without bleeding. Why?

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Correct answer: D — Dilutional anaemia from excessive IV fluids

Alpha-blockade reverses chronic catecholamine-induced vasoconstriction, expanding intravascular volume by up to 1-2L. This causes haemodilution and an apparent drop in haematocrit – expected and beneficial, indicating adequate alpha-blockade.

Reference: RCOA – 2023 – Endocrine anaesthesia; Association of Anaesthetists – 2020 – Phaeochromocytoma