Multiple myeloma and kidney disease

Myeloma cells make an unusual protein that can pass into the bloodstream and be filtered by the kidneys. The protein may collect in kidney structures and interfere with their filtering work. Increased calcium released from weakened bone can also contribute to thirst, dehydration, constipation, confusion, or reduced kidney function. Some people have kidney changes without obvious symptoms, which is why blood and urine testing is part of myeloma assessment.

Your care team may check creatinine, calcium, blood counts, and protein in blood or urine, then follow the results over time. Treatment focuses on controlling the myeloma and correcting factors that burden the kidneys. Tell the team about vomiting, diarrhoea, reduced drinking, or medicines and supplements you take; some medicines may need review when kidney function changes. Do not start a high-dose painkiller or supplement without guidance. Myeloma treatment can include [Targeted Therapy](/treatments/systemic-therapy/targeted-therapy/) or [Chemotherapy](/treatments/systemic-therapy/chemotherapy/), depending on the clinical picture.

Contact your oncology team promptly for much less urine, new swelling, persistent vomiting, marked thirst, increasing sleepiness, confusion, or breathlessness. Seek emergency help for severe confusion, fainting, chest pain, or sudden severe weakness. A sudden change can reflect dehydration, high calcium, infection, medication effects, or kidney injury and needs assessment rather than self-treatment.

Ask which kidney tests you need, whether your results are changing, which medicines should be avoided or adjusted, and how much fluid is suitable for you. You can also ask how the treatment plan protects kidney function and when repeat blood or urine tests are needed.