10th July 2026

Diuretics

In renal impairment, potassium-sparing diuretics, including spironolactone, amiloride, and triamterene, are more likely to cause hyperkalaemia. It is essential to monitor renal function and potassium when commencing these medications. They are contraindicated in CKD with a creatinine clearance < 30 mL/ 1.73 m2. Loop diuretics (furosemide, bumetanide and torasemide) are more likely to cause hypokalaemia in CKD. According to NICE CKS, renal function and electrolytes should be monitored more frequently (day 5-7), particularly if patients have:

• CKD 3 or higher
• Age 60 +
• Relevant comorbidities, e.g. diabetes mellitus
• Also taking ACE-I, MRA, angiotensin II receptor antagonists (AIIRA). 

Once stabilised on treatment, measure renal function and serum electrolytes at least once every 6 months.

Review the serum creatinine level and estimated glomerular filtration rate (eGFR):

• As per the NICE CKS guidelines, an increase in creatinine of 30–50% (or to greater than 200 micromol/L) or an eGFR rate less than 30 mL/min/1.73 m2 should prompt clinical review of volume status and dose reduction or withdrawal of diuretics (if the person is hypovolaemic). 
• If there is an increase in creatinine of more than 50% or to greater than 256 micromol/L (eGFR approximately 20–25 mL/min/1.73 m2), assess volume status, check blood pressure, review other renal function tests, including electrolytes and proteinuria, and review other medications for nephrotoxic agents. If the person is hypovolaemic, stop the diuretic; otherwise, manage accordingly. If there is any uncertainty, seek specialist advice urgently. 

Drug resistance may be encountered in diuretic use, particularly loop diuretics; this may be overcome by increasing the dose, administering a continuous infusion, small frequent doses, or concomitant administration of another diuretic.