Calcium-alkali syndrome in post-surgical hypoparathyroidism

Milk-alkali syndrome or its up-to-date definition ‘calcium-alkali syndrome’ (CAS),1 is characterized by the triad of hypercalcemia, metabolic alkalosis and various degrees of renal failure, due to the intake of variable amounts of calcium and absorbable alkali. Its initial description dates back to the early 20th century when ‘alkali powders’ became a popular therapy for peptic ulcer disease.2 In 1923, two researchers from the Mayo Clinic, Leo Hardt and Andrew Rivers,3 described the adverse effects of this treatment, and in the three following decades communications about toxicity of Sippy's protocol were frequent.4 CAS has become a rare cause of hypercalcemia (<1% of cases) since proton pump inhibitor therapy was introduced in the 1990s.5,6 Nevertheless, it remains the third most common cause of hypercalcemia and the second most frequent cause of severe hypercalcemia among inpatients.5 The main reason for the rise of incidences of CAS is the increase of calcium carbonate use for prophylaxis and treatment of osteoporosis in post-menopausal women. Notably, any situation in which an overload of calcium and alkaline element coexist fosters a risk for CAS. We describe three patients who developed this syndrome in the setting of a post-surgical hypoparathyroidism. ### Case 1 A 71-year-old woman was admitted to our hospital with a 10-day history of nicturia, polyuria, fatigue, nervousness, insomnia and headache. Her past medical history included hypertension, treated with lisinopril and hydrochlorothiazide (20/12.5 mg/day), mild chronic renal failure (creatinine, 1.6 mg/dl) and primary hyperparathyroidism. She had undergone total thyroidectomy and parathyroid resection 2 years earlier and required a second intervention 1 year later because of a new mediastinal parathyroid adenoma. At the time she developed permanent post-operative hypothyroidism and hypoparathyroidism, and calcium carbonate (900 mg/day), calcitriol (1 µg/day) and levothyroxine (100 µg/day) were started. At admission laboratory results were as follows: serum creatinine, 2.4 mg/dl; urea, 104 mg/dl; …