A 64-year-old morbidly obese female was admitted with a history of bilateral lower leg ulceration, chronic venous insufficiency and biventricular cardiac failure. There was no relevant family history. She was commenced on furosemide and prophylactic enoxaparin. Biochemical investigations showed persistently elevated serum potassium concentrations (5.7 to 8.2 mmol/L) and low sodium levels (111 to 131 mmol/L). She had not been prescribed non-steroidal anti-inflammatory agents, angiotensin converting enzyme inhibitors or potassium-sparing diuretics. An oral glucose tolerance test and a short synacthen test was normal. Plasma aldosterone was grossly elevated at >3300 pmol/L (28445), as was plasma renin at 32.2 nmol/L/h (0.392.03). Urinary sodium excretion was <5.0 and potassium 5.2 mmol/L respectively. She had a normal sweat test. She went on to develop renal impairment (creatinine 175 μmol/L) with a normal anion gap metabolic acidosis. Urine output was normal and she remained normotensive. Renal tract ultrasound was normal. A diagnosis of type IV renal tubular acidosis was considered. It was assumed that she had renal resistance to aldosterone, or pseudohypoaldosteronism (PHA). Furosemide and enoxaparin were withdrawn and she was treated with intravenous fluids and oral bicarbonate. Her electrolyte imbalance and renal function normalized, whilst aldosterone fell to 916 pmol/L and renin to 4.54 nmol/L/h.
Two main forms of PHA have been described which differ in the presence (PHA type 2, or Gordons syndrome) or absence (PHA type 1) of hypertension. PHA type 1, with which our patient appears to present, is associated with salt wasting leading to dehydration, hypotension, hyperkalemia, and metabolic acidosis. Sporadic cases and two familial forms, one autosomal dominant and one autosomal recessive, have been described. The autosomal dominant and sporadic form manifest milder salt wasting. We speculate that the administration of furosemide and enoxaparin triggered the development of the severe electrolyte abnormalities.