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Abstract: PO1474

An Unusual Source of Hypercalcemia

Session Information

Category: Trainee Case Report

  • 902 Fluid, Electrolyte, and Acid-Base Disorders: Clinical

Author

  • McCoy, JoBeth, Vanderbilt University Medical Center, Nashville, Tennessee, United States
Introduction

Hypercalcemia is a common electrolyte abnormality seen in daily practice. This case describes elevated serum calcium from a common cause, but an unexpected source.

Case Description

A 62-year-old female presented with complaints of fatigue, weight loss, and weakness. She was found to have a calcium level of 14mg/dL, acute kidney injury with a creatinine of 2.9 mg/dL from a baseline of 1.6mg/dL, and severe weight loss of 60lbs in the past 6 months. She had been evaluated for malignancy with no concerning findings. Initial workup included: parathyroid hormone (PTH) 8pg/mL, 25, vitamin D 22ng/mL, and creatinine phosphokinase 75u/L. There was concern for occult malignancy so further workup included a serum and urine protein electrophoresis that was negative, parathyroid hormone-related protein (PTHrp), 1,25 dihydroxy vitamin D, and Histoplasma antigen. She had a full-body computed tomography (CT) scan without contrast to look for occult malignancy which was negative for any granulomas, masses, adenopathy, or bony lesions. 1,25 vitamin D was elevated at 238 pg/mL. PTHrp was elevated at 5.4 pmol/L. It was thought that Positron Emission Testing (PET) was needed and showed extensive skeletal muscle uptake that was nonspecific. With this result, she underwent a biopsy of the quadriceps muscle. She then had electromyography consistent with myositis with a nonspecific pattern. The muscle biopsy showed non-necrotizing intramuscular granulomas consistent with sarcoid-like myositis. She was started on prednisone 60mg daily. Within three days, her serum calcium had decreased to normal.

Discussion

Sarcoidosis is a multisystem disorder of unknown etiology, which is characterized by the accumulation of noncaseating granulomas in involved tissues. The pathogenesis is unclear, but the histopathologic findings of sarcoidosis in the muscles appear as granulomatous inflammation in muscle that leads to muscle fibrosis and tissue injury. The most common is a chronic myopathy with insidious onset of proximal muscle weakness. In our case, the elevated serum calcium and calcitriol guided the diagnosis. Hypercalcemia in granulomatous disease has been described to be secondary to high levels of calcitriol that increase intestinal reabsorption of calcium. Sarcoidosis, though a common entity, can declare itself through extrapulmonary sources and must remain in the differential for all hypercalcemia cases.