Management of Proteinuria and Impaired Renal Function

Optimize ARB Therapy First

The American College of Cardiology recommends continuing losartan at the current dose and uptitrating to a maximally tolerated dose (up to 100 mg daily) for optimal antiproteinuric effect, providing approximately 30% reduction in proteinuria, and adding a thiazide-like diuretic for blood pressure control, with close monitoring of renal function and strict dietary sodium restriction to <2 g/day 1, 2, 3
Do not stop losartan despite elevated creatinine unless there is a >30% increase from baseline or development of refractory hyperkalemia, as recommended by the Kidney Disease: Improving Global Outcomes (KDIGO) guideline 1, 2, 4

The American Heart Association recommends targeting systolic blood pressure <120 mmHg using standardized office measurement, as lower targets provide additional renoprotection in proteinuric patients, with a strength of evidence rated as high 1, 6, 3
Continue metoprolol as a second-line agent for blood pressure control alongside the ARB, as recommended by the European Society of Cardiology 7

Check labs every 2-4 weeks initially, including serum creatinine, eGFR, potassium, and urine protein-to-creatinine ratio, as recommended by the National Kidney Foundation 2, 8, 5
Aim for proteinuria reduction to <1 g/day or at least 30-50% reduction from baseline, with a strength of evidence rated as moderate 3

Restrict dietary sodium to <2.0 g/day (<90 mmol/day) as sodium restriction is synergistic with ARB therapy and enhances antiproteinuric effects, as recommended by the American Heart Association 1, 2, 3, 5
Counsel patients to hold losartan and diuretics during intercurrent illnesses with risk of volume depletion (vomiting, diarrhea, fever), as recommended by the Kidney Disease: Improving Global Outcomes (KDIGO) guideline 1, 2

If proteinuria persists despite maximized losartan (100 mg daily) plus diuretic, consider adding low-dose spironolactone (25-50 mg daily) with careful potassium monitoring, as recommended by the European Renal Association 3
If the patient has diabetes, add an SGLT2 inhibitor (empagliflozin, canagliflozin, or dapagliflozin) for additive renoprotection, with a strength of evidence rated as high 3

Do not discontinue losartan prematurely due to modest creatinine elevation—this is the most common error and removes critical renoprotection, as warned by the National Kidney Foundation 1, 2, 5
Do not use combination ACE inhibitor plus ARB therapy, as this increases adverse effects without additional benefit, as recommended by the American College of Cardiology 2