A 59-year-old postmenopausal woman with a past medical history of Billroth II gastric bypass surgery 15 years before for bariatric purposes, Barrett esophagus, pericarditis secondary to suspected rheumatologic disease status treated with a pericardial window 3 years before, rheumatoid arthritis with negative rheumatoid factor, paroxysmal atrial fibrillation, amiodarone-induced hypothyroidism, and osteoporosis treated with denosumab 3 months before was referred to the emergency department by her endocrinologist after outpatient labs revealed profound hypocalcemia, hypophosphatemia, and hypomagnesemia. The patient had recently returned from vacation, where she experienced 2-3 episodes of diarrhea. She reported compliance to her medications, which included 50,000 IU ergocalciferol daily and 630 mg calcium citrate 2-3 times daily, apart from taking a decreased dose of calcium for the last 4 days of her vacation since she was running low on pills. She noted fatigue and intermittent tingling in her hands, feet, and perioral region for 2-3 days prior to admission. She denied weight loss, fever, muscle cramping, seizures, loss of consciousness, or lightheadedness.\nOn presentation, the patient was afebrile with a temperature of 98.2ºF, blood pressure of 136/74 mmHg, heart rate of 71 beats/min, and respiratory rate of 15 breaths/min. Her oxygen saturation was 100% on room air. Physical examination revealed a well-appearing woman with a body mass index (BMI) of 30 kg/m2 in no acute distress. Neck was supple with no thyromegaly. There were no abnormalities on cardiac or pulmonary exam. Abdomen was soft, nontender, and nondistended with normal bowel sounds. Patient had a positive Chvostek's sign. No muscle twitches or spasms were appreciated. Strength, sensation, reflexes, and cranial nerves were intact. The patient had no signs of confusion or psychosis.\nBlood tests from the emergency department revealed a calcium of 5.8 mg/dL, phosphorus of <1 mg/dL, and magnesium of 1.7 mg/dL. Albumin was 3.8 g/dL, so the corrected calcium was 6.0 mg/dL. Ionized calcium was 0.8 mg/dL. Parathyroid hormone was 136 ng/L. 25-Hydroxy vitamin D was normal at 46 ng/mL, and 1-25-hydroxy vitamin D was normal at 30 pg/mL. Urinalysis was within normal limits, and urine calcium was <2 mg/dL. Creatinine was 0.61 mg/dL, and blood urea nitrogen was 11 mg/dL. TSH was normal at 0.78 μU/mL. An electrocardiogram performed in the emergency department showed normal sinus rhythm with a corrected QT interval of 493 ms.\nIn the emergency department, the patient was given 2 g of IV magnesium sulfate, 30 mmol of IV sodium phosphate, and 1 g of IV calcium gluconate. During her 4-day hospital stay, the patient continued to receive IV calcium, as well as oral calcitriol, phosphate, and magnesium. When she was able to consistently maintain serum calcium of at least 8.0 mg/dL on oral calcium citrate supplementation, she was discharged with a calcium level of 8.0 mg/dL, magnesium of 1.9 mg/dL, and phosphorus of 2.3 mg/dL. She was instructed to take calcium citrate of 1260 mg 4 times daily, calcitriol of 0.25 mcg 2 times daily, phosphorus of 250 mg 3 times daily, and magnesium oxide of 400 mg 2 times daily and to be followed up closely with her endocrinologist. Since discharge, the patient has been able to maintain adequate calcium levels on a low dose of calcium supplementation, and she is interested in considering further doses of denosumab.
A 55-year-old Caucasian woman on peritoneal dialysis for the last three years due to lupus nephritis was seen in the dialysis clinic for a routine follow-up. Her medical problems included hypertension, secondary hyperparathyroidism, and documented osteoporosis on DEXA scan (Dual energy X-ray absorptiometry) with left femoral neck BMD at 0.637 g/cm2; 2.9 standard deviation below peak BMD. Her medications included Amlodipine 5mg, Cinacalcet 60 mg, and Epoetin weekly injections.\nShe complained of fatigue, muscle cramps, and paresthesias of the hands and feet for the past week. Vital signs were stable. Physical exam was unremarkable with negative Chvostek's and Trousseau's signs. Laboratory work-up showed profound hypocalcemia with a total calcium level of 6.4 mg/dL with corrected calcium level of 6.9mg/dL (serum albumin level of 3.4 g/dL) and markedly increased serum intact PTH level (iPTH) of 2601 pg/mL (). Serum phosphate and serum alkaline phosphatase level was within normal reference range at 3.1 mg/dl and 84 U/L, respectively. Upon history taking, she was found to have received a new medication, denosumab 60mg subcutaneously, prescribed by her rheumatologist 10 days prior to the current presentation.\nBefore the administration of denosumab, the patient had normal serum values of calcium (9.5 mg/dL), phosphorus (3.8 mg/dL), alkaline phosphatases (96 U/L), and 25 vitamin D with slightly elevated iPTH level at 442 pg/mL. The patient was supplemented with 3,000 mg/dL of oral calcium along with oral Calcitriol 0.5mcg daily and Cinacalcet was held. The peritoneal dialysis solution was also changed from low calcium to regular calcium. All these measures resolved her symptoms with serum calcium normalizing (corrected calcium, 8.7 mg/dL) 5 days later whereas iPTH took almost 4 weeks to come back to baseline level (). Subsequently, she was managed as an out-patient with close monitoring of calcium homeostasis.