NutriStack
What is happening. Tenofovir disoproxil-induced proximal renal tubular dysfunction can cause urinary potassium wasting and hypokalemia, sometimes with metabolic acidosis, in patients developing a Fanconi-like syndrome. While some patients may require potassium repletion, others (particularly those with declining renal function from tenofovir nephrotoxicity) can be at risk of hyperkalemia, so unsupervised potassium supplementation is hazardous. Falling or abnormal potassium during TDF therapy should be interpreted in the context of kidney function rather than treated empirically.
Mechanism. TDF can damage proximal tubular cells, impairing electrolyte reabsorption and causing renal potassium wasting (with phosphate, magnesium, and bicarbonate loss). Concurrent decline in glomerular filtration can paradoxically raise hyperkalemia risk, making potassium balance unpredictable.
Recommendation. Do not take potassium supplements while on TDF without monitoring serum potassium and renal function. Treat documented hypokalemia under clinical supervision and investigate for tubular toxicity. In patients with reduced eGFR or those also on ACE inhibitors, ARBs, or potassium-sparing diuretics, potassium supplementation can precipitate dangerous hyperkalemia. Persistent electrolyte disturbance should prompt reassessment of the tenofovir formulation.