LAUSR

A 3-year-old female was admitted for evaluation and management of severe hypercalcemia in the setting of pan-sensitive Escherichia coli pyelonephritis. Past medical and surgical history were negative except for chronic constipation. There was no significant family history. She had appropriate growth for her age, weight, and length with all measuring around the 70th percentile. Vital signs were remarkable on presentation for hypertension to 130/80 when calm and relaxed (95th percentile for gender, age, and height is 106/55 mmHg). She did not have dysmorphic features and her exam was within normal limits, aside from fussiness. Initial blood chemistry panel showed elevated corrected total calcium level to 16.4 mg/dL (reference interval 8.6– 10.1), ionized calcium of 8.20 mg/dL (4.6–5.3), magnesium of 1.9 mg/dL (1.8–2.5), and phosphorus of 4.7 mg/dL (3.4– 5.9). She had a high bicarbonate level of 29 mEq/L (reference interval is 18–27), low serum potassium of 3.4 mEq/L (3.5– 5.3), low albumin of 2.3 g/dL (3.5–4.8) with normal sodium of 143 mEq/L (136–145), chloride of 108 mEq/L (97–111), BUN of 12 mg/dL (5–18), and creatinine of 0.42 mg/dL (0.3– 0.7). Complete blood count showed low hemoglobin of 9.2 g/ dL (reference interval is 10.5–14) with normal white blood count of 9.3 × 10/L (4.8–13.5) and platelets of 361 × 10/L (150–450). Initial treatment included intravenous (IV) antibiotics with ampicillin 50 mg/kg every 6 h along with IV 0.9% saline hyperhydration and IV furosemide 1 mg/kg every 12 h in an effort to improve her severe hypercalcemia. Additional lab work revealed suppressed parathyroid-hormone (PTH) level of 1 pg/mL (reference interval 12–88) with normal parathyroid hormone–related peptide (PTHrP) of 2.1 pmol/L (normal < 4.2). The 1,25-dihydroxyvitamin D (1,25OH2D3) level was significantly elevated at 121 pg/mL (reference interval is 19.9–79.3), and 25-hydroxyvitamin D (25OHD3) level was normal at 32 ng/mL (30–100). She had normal vitamin A level, thyroid function tests, and LDH. Her ACE level was 31U/L (normal 18–90) and her ANAwas negative. The initial urine calcium-to-creatinine ratio was elevated to 1.38 mg/mg (normal for age < 0.2). A kidney ultrasound with Doppler showed normal renal vasculature with bilaterally enlarged kidneys for age and height, along with increased echogenicity of the renal pyramids consistent with nephrocalcinosis. CT imaging of her head, neck, chest, abdomen, and pelvis were obtained to evaluate for malignancy-induced hypercalcemia. It did show left periaortic enlarged lymph nodes concerning for possible malignancy. After consultation with pediatric oncology, she underwent a bone marrow aspirate and biopsy which was negative for malignancy. With the normal bone marrow studies and other findings, the lymph nodes were felt to be reactive in nature. When afebrile and overall clinically improving, she was transitioned to oral amoxicillin-clavulanate to complete treatment of her pyelonephritis. As hypercalcemia persisted despite fluids and furosemide, she was started on subcutaneous calcitonin 4 units/kg/dose every 12 h for three doses. This resulted in a decrease in total calcium to 12.5 mg/dL. Unfortunately, the calcium level increased upon discontinuation of the calcitonin; therefore, pamidronate 0.5 mg/kg every The answers to these questions can be found at https://doi.org/10.1007/ s00467-020-04711-3.