A case of acute phosphate nephropathy
A 74-year-old woman presented with a 2-day history of abdominal pain and nausea, 1 week after undergoing upper and lower endoscopies. Her comorbidities included hypertension, dyslipidaemia, sigmoid diverticulosis, transient ischaemic attack, peripheral vascular disease and mild valvular heart disease.
Medications taken before admission included telmisartan–hydrochlorothiazide, sustained-release verapamil, prazosin, rosuvastatin and aspirin.
Admission blood tests indicated acute kidney injury, with a serum creatinine concentration of 218 μmol/L (reference interval [RI], 46–99 μmol/L) and an estimated glomerular filtration rate of 19 mL/min/1.73 m2 (RI, > 60 mL/min/1.73 m2); her creatinine level 7 months earlier was 69 μmol/L. She was also hypokalaemic (potassium level, 2.9 mmol/L [RI, 3.5–5.1 mmol/L]), hypocalcaemic (corrected calcium concentration, 1.97 mmol/L [RI, 2.15–2.6 mmol/L]) and uraemic (urea concentration, 14.4 mmol/L [RI, 2.9–8.2 mmol/L]). However, she was normophosphataemic (phosphate level, 1.14 mmol/L [RI, 0.81–1.45 mmol/L]). Her urinary sediment was relatively benign, with a protein-to-creatinine ratio of 17 g/mol (RI, < 15 g/mol), an albumin-to-creatinine ratio of 3.4 g/mol (RI, < 1 g/mol) and no red cells present. Renal ultrasound showed normal sized kidneys with no evidence of obstruction.
A medication review…