Hypocalciuric Hypercalcemia due to Impaired Renal Tubular Calcium Excretion in a Type 2 Diabetic Patient

The case we presented here was a 73-year-old gentleman, who was admitted to endocrinology department due to recurrent fatigue for 1 year. He had medical histories of type 2 diabetes for 18 years and developed CKD 4 years ago. He also suffered from dilated cardiomyopathy, and coronary heart disease, moderate sleep apnea syndrome, primary hypothyroidism, and gout. His treatment regimen was complicated which included Caltrate D and compound α-keto acid (1200 mg calcium/d). Laboratory examination revealed that his serum calcium level elevated, 24-hour urine calcium output decreased, PTH level was suppressed, and 25-hydroxyvitamin D was in normal low range. No other specific abnormalities were found in serum bone turnover markers, ultrasonography, computed tomography, and bone scintigraphy. The diagnosis was suggested to be hypocalciuric hypercalcemia but was different from familial or acquired hypocalciuric hypercalcemia which were featured by elevated PTH level. The patient was asked to restrict calcium intake and to take diuretics; then his serum calcium level gradually lowered. In brief, patients with CKD could present with hypocalciuric hypercalcemia due to impaired renal calcium excretion. In this case, calcium restriction should be applied for treatment.