Losartan Does Not Cause Kidney Stones
Losartan does not cause kidney stones; in fact, research suggests it may actually help prevent calcium oxalate stone formation through its antioxidant and anti-inflammatory effects on renal tubular cells. 1
Evidence Against Losartan Causing Kidney Stones
The available evidence demonstrates no association between losartan and kidney stone formation. The major clinical trials examining losartan's effects on kidney function—including RENAAL and JLIGHT—did not report kidney stones as an adverse event despite involving thousands of patients followed for extended periods. 2, 3
Potential Protective Effect Against Stone Formation
Recent experimental evidence suggests losartan may actually reduce kidney stone risk through several mechanisms:
Reduction of oxidative stress: Losartan ameliorates calcium oxalate-induced elevation of stone-related proteins (OPN, CD44, MCP-1) in renal tubular cells by inhibiting NADPH oxidase and reducing reactive oxygen species production. 1
Anti-inflammatory effects: Losartan suppresses the NF-κB pathway activation that promotes renal crystallization and stone formation in hyperoxaluric conditions. 1
Uricosuric properties: Unlike other ARBs, losartan uniquely increases urinary uric acid excretion while simultaneously raising urinary pH, which may reduce the risk of uric acid stone formation. 4, 5
Clinical Context and Monitoring
While losartan does not cause kidney stones, clinicians should be aware of its expected renal effects:
Predictable creatinine elevation: A 10-20% rise in serum creatinine is expected due to hemodynamic changes (efferent arteriolar vasodilation) and represents a physiological response rather than kidney injury. 6
Monitoring protocol: Check serum creatinine and potassium within 1-2 weeks after starting losartan or increasing doses, particularly in patients with baseline eGFR <45 mL/min/1.73 m². 7, 6
Proteinuria reduction: Losartan significantly reduces proteinuria by 20-47% in patients with chronic kidney disease, which is a renoprotective effect beyond blood pressure control. 3, 8
Important Safety Considerations
Avoid dual RAAS blockade: Never combine losartan with ACE inhibitors or direct renin inhibitors, as this increases risks of hyperkalemia and acute kidney injury without added benefit. 7, 9
Hyperkalemia risk: Monitor potassium levels closely, especially in patients with CKD, diabetes, or those taking potassium-sparing diuretics or NSAIDs. 9, 6
Temporary suspension: Hold losartan during intercurrent illness, IV contrast administration, bowel preparation, or before major surgery to avoid acute kidney injury. 9, 6