Tenofovir induced Fanconi syndrome: A rare cause of hypokalemic paralysis
A 55-year-old female presented with acute onset weakness of all four limbs of one day duration. She also noted increased fatigue and polyuria over the past three days. There was no past history of diarrhea or upper respiratory infection in the recent past or any past history of neurological or renal disorders. She was diagnosed to have HIV infection 7 years back and was started on tenofovir, emtricitabine and atazanavir 10 months ago. Physical examination revealed cachexia and muscle power of 2/5 in all four limbs. Deep tendon reflexes were sluggish and pin prick sensation was normal. There was no respiratory distress and her vital parameters were also normal.\nIn the emergency room her potassium was 1.66 meq/l, serum glucose 112 mg/dl, serum sodium 140 meq/l, serum chloride 118 meq/l, serum bicarbonate 9.4 meq/l, serum phosphorus 2.2 mg/dl and calcium 8.4 mg/dl. Patient had normal anion gap metabolic acidosis and hence renal tubular acidosis was suspected. Urine anion gap was positive (15). Her serum creatinine was 2.2 mg/dl, urea 41 mg/dl, urine analysis showed 2 + albuminuria, 3 + glucosuria, 2 + myoglobinuria, pH 5.5, spot potassium 32 meq/l, spot sodium 75 meq/l and spot chloride 92 meq/l. Arterial blood gas values were pH 7.194, pCO2 23.4, pO2 107, bicarbonate 8.8, lactate 2.5. Complete blood count showed high erythrocyte sedimentation rate of 62 and creatinine phosphokinase was 616, rest were within normal limit.\nFS leading to hypokalemic paralysis was suspected given the presence of a hyperchloremic metabolic acidosis, hypokalemia, hypophosphatemia, glucosuria and proteinuria. The patient was aggressively rehydrated with intravenous fluids. She required replacement with intravenous potassium chloride for 2 days to keep potassium above 3 meq/l. Patients muscle power dramatically improved within 12 h of hospital admission with potassium correction. Other renal parameters, also improved slowly with treatment. Tenofovir was stopped as we suspected it to be the cause for FS.