From the Guidelines
Multiple myeloma can cause hyponatremia through various mechanisms, including renal dysfunction, which is a common complication of the disease. According to a recent study published in the Blood Cancer Journal in 2023 1, acute kidney injury (AKI) caused by light chain cast nephropathy (LCCN) is one of the major complications from multiple myeloma (MM), and it can lead to impaired sodium handling. The study found that 16-31% of patients with MM have AKI at diagnosis, and 36-45% have an estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m2, which can affect sodium levels.
Some of the key mechanisms by which multiple myeloma can cause hyponatremia include:
- Renal dysfunction due to light chain damage to kidneys
- Syndrome of inappropriate antidiuretic hormone secretion (SIADH)
- Hypercalcemia from bone destruction in myeloma, which can interfere with renal tubular function and sodium reabsorption
- Production of paraproteins that increase serum osmolality, leading to pseudohyponatremia
Patients with myeloma-related hyponatremia may require sodium restriction, fluid restriction, or medications like tolvaptan depending on severity and underlying mechanism. Treatment of the underlying multiple myeloma with appropriate chemotherapy regimens is essential for long-term management of hyponatremia, as it can help improve renal function and reduce the risk of hyponatremia. Regular monitoring of electrolytes is important for patients with multiple myeloma, especially during active treatment phases, to promptly identify and manage any electrolyte imbalances, including hyponatremia 1.
From the Research
Multiple Myeloma and Hyponatremia
- Multiple myeloma can cause hyponatremia, as evidenced by several studies 2, 3, 4, 5, 6.
- The development of hyponatremia due to syndrome of inappropriate antidiuretic hormone secretion (SIADH) is well recognised in multiple myeloma (MM) 2.
- Bortezomib, a medication used to treat multiple myeloma, can induce SIADH, leading to hyponatremia 2, 3.
- In some cases, the use of tolvaptan, a vasopressin receptor-2 antagonist, can permit the continuation of anti-MM therapy without the development of hyponatremia 2.
- The mechanism of hyponatremia in multiple myeloma patients treated with bortezomib, lenalidomide, and dexamethasone combination therapy is not fully understood, but may involve inflammatory cytokines 3.
- Hyponatremia in multiple myeloma patients can be true hyponatremia, rather than pseudohyponatremia, due to the positively charged M proteins 6.
- Pseudohyponatremia can occur in multiple myeloma patients with paraproteinemia, where the serum has increased viscosity 5.