How should I manage a 73-year-old woman on a triamterene‑hydrochlorothiazide combination who has possible urinary tract infection, stage 3a chronic kidney disease, hypokalemia, and type 2 diabetes with an A1c of 6.7%?

Management of a 73-Year-Old Woman on Triamterene-HCTZ with Multiple Comorbidities

Stop triamterene-HCTZ immediately and switch to hydrochlorothiazide 25 mg alone, as the triamterene component is contraindicated in CKD stage 3a and is the primary cause of her hypokalemia. 1, 2

Immediate Medication Adjustment

The combination of triamterene with hydrochlorothiazide is causing paradoxical hypokalemia in this patient with reduced renal function. In elderly patients with CKD stage 3a (eGFR 52 mL/min), triamterene accumulates due to impaired renal clearance, and its diuretic effect becomes negligible while the thiazide component continues to waste potassium 3, 2. Studies demonstrate that in elderly patients with reduced creatinine clearance, plasma concentrations of triamterene increase dramatically while pharmacodynamic effects (urine flow and sodium excretion) decrease proportionally, essentially leaving only the potassium-wasting effect of the thiazide active 3.

• Discontinue triamterene-HCTZ 37.5-25 mg immediately 1, 3
• Start hydrochlorothiazide 12.5-25 mg daily as monotherapy 2
• The risk of thiazide-induced hypokalemia is 11 times higher than in non-users, but this is still preferable to the current combination which provides no benefit from the triamterene component in CKD 2

Hypokalemia Correction Protocol

Target serum potassium of 4.0-5.0 mEq/L, as both hypokalemia and hyperkalemia increase mortality risk, especially in patients with diabetes and cardiovascular disease. 4, 1

• Check and correct magnesium first—this is the most common reason for refractory hypokalemia and must be corrected before potassium will normalize (target >0.6 mmol/L or >1.5 mg/dL) 1
• Start oral potassium chloride 20-40 mEq daily, divided into 2-3 doses 1
• Recheck potassium and renal function within 3-7 days after starting supplementation, then every 1-2 weeks until stable, then at 3 months, then every 6 months 1
• Increase dietary potassium through fruits, vegetables, and low-fat dairy (4-5 servings daily provides 1,500-3,000 mg potassium) 1

Do not add a potassium-sparing diuretic (spironolactone, amiloride) in this patient with CKD stage 3a, as the combination with reduced renal function dramatically increases hyperkalemia risk. 1, 5

UTI Management

If symptomatic (dysuria, urgency, frequency, fever), treat empirically with antibiotics and send urine culture. 4

• For asymptomatic bacteriuria, repeat clean-catch urinalysis with culture before treating, as treatment may not be indicated in elderly women without symptoms 4
• Avoid fluoroquinolones if possible in elderly patients with diabetes due to increased risk of adverse effects 4
• Ensure adequate hydration during UTI treatment, but monitor for volume overload given CKD 4

CKD Stage 3a Management

Optimize blood pressure control to slow CKD progression, targeting <140/90 mmHg (or <130/80 mmHg if tolerated without symptomatic hypotension). 4

• Continue monitoring eGFR and urine albumin every 3-6 months 4
• Avoid NSAIDs entirely—they cause acute renal failure, worsen CKD progression, and increase hyperkalemia risk when combined with potassium supplementation 4, 1
• Consider adding an ACE inhibitor or ARB if albuminuria is present (≥30 mg/g), as these agents slow CKD progression and reduce renal potassium losses, potentially eliminating the need for chronic potassium supplementation 4, 1
• If ACE inhibitor or ARB is started, reduce or discontinue potassium supplementation and monitor potassium within 7-10 days, as these medications reduce renal potassium excretion 4, 1

Diabetes Management (A1c 6.7%)

Individualize HbA1c target between 6.5-8.0% in this patient with CKD stage 3a, balancing glycemic control against hypoglycemia risk. 4

• An A1c of 6.7% is acceptable in CKD stage 3a, but tighter control (<7%) may be appropriate if achievable without hypoglycemia 4
• HbA1c remains accurate for monitoring glycemic control down to eGFR 30 mL/min/1.73 m² 4
• Consider SGLT2 inhibitors or GLP-1 receptor agonists if additional glucose-lowering is needed, as these agents provide cardiovascular and renal benefits 4
• Metformin can be continued at eGFR 52 mL/min but should be reduced if eGFR falls to 30-45 mL/min and discontinued if eGFR <30 mL/min 4
• Avoid sulfonylureas (glyburide) in CKD due to hypoglycemia risk; if sulfonylurea needed, use glipizide with conservative dosing 4

Critical Monitoring Schedule

• Days 3-7: Recheck potassium, magnesium, creatinine, and eGFR after stopping triamterene-HCTZ 1
• Week 2: Repeat electrolytes and renal function if initial values show improvement 1
• Monthly for 3 months: Monitor potassium and renal function, then every 3-6 months thereafter 1
• Every 3-6 months: Monitor HbA1c, eGFR, and urine albumin-to-creatinine ratio 4

Common Pitfalls to Avoid

• Never continue triamterene in CKD stage 3a—it accumulates, loses efficacy, and increases risk of crystal-induced acute kidney injury 3, 6, 7
• Never supplement potassium without checking magnesium first—this is the single most common reason for treatment failure 1
• Never combine potassium supplements with potassium-sparing diuretics in CKD—this dramatically increases hyperkalemia risk 1, 5
• Never use NSAIDs in this patient—they cause acute renal failure, worsen CKD, and increase hyperkalemia risk 4, 1
• Never assume triamterene-HCTZ combinations are appropriate in elderly patients with CKD—the triamterene component becomes ineffective while toxicity risk increases 3, 2