Portal de Periódicos da CAPES

The kidney and magnesium regulation

1983; Elsevier BV; Volume: 23; Issue: 5 Linguagem: Inglês

10.1038/ki.1983.93

1523-1755

Principal discussant John H. Dirks,

Magnesium in Health and Disease

Case presentationsPatient 1.A 33-year-old woman was admitted to St. Paul's Hospital in Vancouver, B.C. with cramps in her hands and feet.An intestinal bypass operation had been performed 4 years earlier because of obesity (her weight was 122.5 kg prior to operation).A cholecystectomy had been performed at the same time.Over the next 2 years she lost 61.2 kg and was well except for episodic diarrhea.One year prior to the present admission, she had been admitted to the hospital; the serum magnesium was 0.56 mEq/liter and calcium was 6.6 mg/dl.Serum magnesium was corrected over 24 hours with magnesium sulfate to 2.16 mEq/liter, and the serum calcium level rose spontaneously to 8.2 mg/dl over 3 days.A few weeks prior to the present admission, her bowel movements increased to 20 to 30 per day, and she noticed progressive weakness, cramps in her hands, and circumoral numbness.On admission, blood pressure was 130/90 mm Hg; pulse rate was 80 lying and standing.The only abnormal physical finding was a positive Chvostek's sign.Laboratory results were as follows: sodium, 144 mEq/liter; potassium, 3.1 mEq/liter; chloride, 109 mEq/liter; total C02, 29 mmol/liter; BUN, 7 mg/dl; serum creatinine, 0.7 mg/dl; calcium, 6 mg/dl (normal, 8.6-10.3);magnesium, 0.4 mEq/liter (normal, 1.4-2.10); total protein, 5.6 g/dl; and serum albumin, 3.3 g/dl.Hemoglobin was II g/dl.Serum vitamin B1,, serum folate, and serum parathyroid hormone were normal.Results of urinalysis were normal.A spot urine magnesium concentration was 0.5 mEq/liter.Electrocardiogram was normal, including the QT interval.Because of marked hypomagnesemia, hypocalcemia, and tetany, the patient was given 8 mEq of magnesium as 50% magnesium sulfate hourly for 6 hours and then 8 mEq every 4 hours; she also received 25 mEq of potassium chloride twice daily.Serum magnesium rose to 0.96 mEq/liter within 3 hours and to 3.6 mEq/liter after 11 hours.She was given 500mg of calcium salts three times daily, and the plasma calcium rose to 8.6 mg/dl.Potassium rose to 3.5 mEq/liter.All signs and symptoms of hypomagnesemia and hypocalcemia disappeared and remained absent while she received 48 mEq of magnesium per day.The 24-hour urinary magnesium excretion rose to 42 to 50 mEq/Iiter; this value reflects a fractional urinary magnesium excretion of 28% to 42%.