Haematology & OncologyPending review

Myeloma

A malignant clone of plasma cells expands in the bone marrow and pours out a single monoclonal immunoglobulin, so the clinical picture (bone destruction, renal failure, anaemia and hypercalcaemia) follows directly from marrow infiltration and the toxic paraprotein, summarised as CRAB.

In a nutshell

A plasma cell clone secretes a toxic monoclonal paraprotein while activating osteoclasts in the marrow, producing the CRAB features (hypercalcaemia, renal impairment, anaemia and bone disease) as one interconnected process rather than four separate problems.

Classic presentation

An older adult with persistent back pain, fatigue and recurrent infections, found to have anaemia, renal impairment and hypercalcaemia on bloods.

Key points

CRAB features share mechanisms: osteoclast activation causes bone lysis and the released calcium causes hypercalcaemia; light chains cause direct renal toxicity; marrow crowding causes anaemia.

You’ve reached the end of the preview

This topic is part of full high-yield access. Create a free account to read every key point, first-line investigation and exam trap — or browse the free sample topics without one.

Educational content pending clinical review. Not medical advice.