MEDizzy - A 42 year old woman with IgA nephropathy and stage 3 CKD

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Nephrology and urology

A 42 year old woman with IgA nephropathy and stage 3 CKD (eGFR 45 mL/ min/1.73 m2 ) is developing proteinuria (protein:creatinine ratio is 120 mg/mmol). BP is 158/86 mmHg and she is commenced on an ACE inhibitor (lisinopril 10 mg daily). Two weeks later her eGFR has fallen to 37 mL/min/1.73 m2 and her potassium has risen from 5.2 to 5.9 mmol/L, although BP and protein:creatinine ratio have fallen to 146/82 mmHg and 30 mg/ mmol, respectively. She is already on a low-potassium diet. What is the most appropriate management?

ExplanationThere is good evidence that ACE inhibitors are the drug of choice to treat hypertension and reduce proteinuria in patients with CKD and protein:creatinine ratio >100 mg/mmol, and initiation of lisinopril has been partially effective in this patient. The fall in eGFR of <20% is acceptable and all alternative measures should be taken to reduce potassium before stopping the ACE inhibitor. Calcium resonium is only suitable for short-term management of hyperkalaemia due to risk of bowel perforation. While BP is suboptimal, increasing the lisinopril or adding a β-blocker are not recommended at this level of potassium. A thiazide would be more appropriate as this will have the combined benefit of reducing BP and lowering potassium.