Myeloma

AKI is relatively common in myeloma, occuring in 20-30% of affected individuals at the time of diagnosis, and is mainly due to the nephrotoxic effects of the abnormal immunoglobulins

Aetiology

• Age at presentation ~60 years, greater incidence in males

Pathophysiology

• Cancer of plasma cells involving excessive clonal production of immunoglobulins (proteins)

• Collections of abnormal plasma cells can accumulate in the bone marrow and/or soft tissue

• Impairment of production of normal blood cells leads to anaemia

• Monoclonal production of a paraprotein (abnormal antibody), which can potentially cause renal dysfunction

Renal manifestations

• 20-40% present with renal impairment

• Multi-factorial aetiology

• AL amyloidosis

• Monoclonal immunoglobulin deposition (light-heavy chains)

• Light chain cast nephropathy

• Dehydration

• Hypercalcaemia

• Renotoxic exposure - contrast, bisphonates, NSAIDs

Clinical presentation

• Classic presentation - back pain and renal failure

Symptoms

• Bone pain

• Weakness

• Fatigue

• Weight loss

• Recurrent infections

Signs

• Anaemia

• Hypercalcaemia

• Renal failure

• Lytic bone lesions

Investigations

• Bloods - serum protein electrophoresis, serum free light chains

• Urine - Bence Jones Protein

• Bone marrow biopsy

• Skeletal survey - lytic bone lesions

• Renal biopsy - not generally needed for diagnosis, but may be needed in complex cases to confirm that myeloma is the cause of the renal dysfunction

Management

• General measures - stop nephrotoxics, manage hypercalcaemia (saline +/- bisphonates)

• Diseases specific - chemotherapy, stem cell transplant

• Supportive - dialysis