Case presentation A 57-year-old female, a retired beautician, was referred to Parkiand Memorial Hospital for evaluation and treatment of persistent hyperkalemia. She had been in excellent health until approximately 12 years earlier, when she underwent a laminectomy for a herniated nucleus pulposus. The surgery was uneventful and her convalescence was uncomplicated except for the loss of 70 lbs (178 to 108 Ibs) during the 7month period that she was confined to a body cast. When the cast was removed, she experienced a syncopal episode. A complete evaluation at another hospital suggested that the syncope was the result of orthostatic hypotension. Pertinent aspects of her workup included a normal electromyogram, electrocardiogram, serum protein electrophoresis, and upper gastrointestinal series. Laboratory findings revealed: hematocrit, 42%; total protein, 8.3 g/dl; albumin, 5.3 g/dl; BUN, 9 mg/ dl; T3 resin uptake, 25%; T4, 4.8 sg/dl; 24-hour urine 17-OH steroids, 12 mg/24 hr (normal <10 mg/24 hr); and 17 ketosteroids, 7 mg/24 hr (normal 5—15 mg/24 hr). Serum electrolytes were reported as normal. She was given 9-a-fiuorocortisol, 0.1 mg/day. The patient continued to complain of dizziness and had several additional hospital admissions over the ensuing 3 years. Her standing blood pressure was 60/30 mm Hg. Neurologic workups continued to be unrevealing. Serum electrolytes remained normal: sodium, 132 mEq/ liter; potassium, 4.5 mEq/liter; carbon dioxide, 24 mEqlliter; and BUN, 18 mg/dl. Treatment with elastic stockings, ephedrine, and an antigravity suit were prescribed. The dose of 9-n-fluorocortisol gradually was increased to 0.6 mg/day. Hyperkalemia (serum potassium, 5.7 mEq/liter) was documented for the first time 8 years ago. Six years ago the 24-hour urinary aldosterone level was "non-detectable" while she was ingesting a low-sodium diet; serum aldosterone was 2 ng/dl 4 hours after assuming the upright posture and receiving a diuretic, and plasma cortisol after ACTH injection was 2 sg/dl at 4 PM. She also had a subnormal response of plasma cortisol to an 8-hour ACTH infusion but the metyrapone test was normal; il-DOC increased to 3 sg/dl and serum cortisol fell slightly. She was advised at that time to increase 9-n-fluorocortisol to 1.0 mg/day. For the past 5 years she has not only been hypotensive, but also severely hyperkalemic, the serum potassium concentrations frequently being greater than 7.0 mEq/liter with a peak value of 9.9 mEq/liter. When the serum potassium exceeded 9.0 mEq/liter, generalized weakness and occasional frank paralysis occurred. Serum potassium values have remained markedly elevated despite therapy with sodium polystyrene sulfonate (Kayexalate). The course has been further complicated by occasional periods of hypokalemia, occurring when the cation exchange resin was increased in conjunction with a decreased intake of potassium. Creatinine clearance 5 years ago was 55 mI/mm. A repeated endocrine evaluation 4 years ago revealed: supine plasma aldosterone, 3 ng/dl (normal 3—10 ng/dl); upright plasma aldosterone, 2 ng/dl (normal 5—30 ng/dl); 24-hr urinary aldosterone, 3 g/24 hr (normal 4—20 g/24 hr); supine plasma renin, 3.5 ng of angiotensin generated/mI! hr (normal 0.5—1.6 ng/ml/hr); 2-hour upright plasma renin, 18.4 ng of angiotensin generated/ml/hr (normal 1.9—3.6 ng/mllhr); 24-hour urinary 17-ketosteroids, 4.8 mg/24 hr (normal 5—15 mg/24 hr); 24-hour urinary 17-OH-steroids, 10.6 mg/24 hr (normal 4—8 mg/24 hr); and plasma cortisol, 30.7 g/dl at 8 AM and 20.4 jsg/dl at noon (normal 7—27 jsg/dl at 9 AM). Although a value for serum potassium was not recorded simultaneously, the most likely diagnosis appeared to be isolated hyperreninemic hypoaldosteronism. One year ago she again experienced periods of weakness, She also had reductions in serum sodium to 106 mEq/liter and elevations in serum potassium to 7.5 mEq/liter despite high doses of sodium polystyrene sulfonate and 9-a-fiuorocortisol. However, her symptoms persisted and the metabolic abnormalities remained difficult to control. For these reasons she was admitted to the Clinical Research Center. Physical examination revealed a pleasant white female who appeared her stated age. The blood pressure was 80/60 mm Hg supine. In the sitting position, the systolic blood pressure was 60 mm Hg, but the diastolic pressure was unobtainable. Respective pulse rates were 60 and 98/mm. The respiratory rate was 18/mm. She was afebrile. The remainder of the physical examination was within normal limits. The laboratory findings were: hematocrit, 38.1%; MCV, 102.2 sodium, 123 mEq/liter; potassium, 6.3 mEq/liter; chloride, 104 mEq/ liter; carbon dioxide content, 15 mM/liter; calcium, 9.5 mg/dl; phosphorus, 3.8 mg/dl; BUN, 33 mg/dl; and creatinine, 1.7 mg/dl. The arterial blood pH was 7.25. Urinalysis disclosed: pH, 6.5; specific gravity, 1.025; and normal sediment. Serum lipids were normal. Serum B12 was less than 100 pg/mI (normal 210—920 pg/mI), and folic acid was 3.2 ng!ml (normal 2—14 ng/ml). Electrocardiogram, chest x-ray, and abdominal computerized tomographic scan were normal. Renal biopsy revealed scattered areas of complete scarring. Other areas appeared completely normal. Specifically the distal tubules and the adjacent interstitium were normal. Each glomerulus, however, displayed a markedly hyperplastic juxtaglomerular apparatus. Electron microscopy and immunofluorescence studies failed to demonstrate any deposits. The biopsy material contained adequate samples both of cortical and medullary sections. Because of evident salt depletion, the patient was given a diet containing 410 mEq of sodium (9.4 g) and 10 mEq of potassium for the first 2 days. A metabolic diet was then given that contained 260 mEq of sodium (6 g), 10 mEq of potassium, and 3000 ml fluid per day. Successive 3-day collections of stool were analyzed; serum and urine