Stepwise Teamwork Approach Saves Patients Extensive Work-Up

Introduction: Hypercalcemia is a relatively common clinical entity that can arise from a variety of etiologies, including primary hyperparathyroidism, malignancies or medications. In most of these cases, the underlying cause can be determined through a thorough clinical evaluation, including a detailed patient history, physical examination and targeted laboratory testing. We present a case with significant hypercalcemia, highlighting the diagnostic approach taken to identify the underlying cause through systematic analysis of the patient's symptoms, laboratory results and imaging studies Case Description: 77-year-old male with past medical history of hypertension, prostate cancer status post-excision and CKD stage IIIB, was transferred from an outside hospital for evaluation of suspected multiple myeloma. Physical exam was stable but initial laboratory work up showed a serum calcium level of 15.3 mg/dL. He was started on IV fluids with a slight improvement in serum calcium level to 12 mg/dl however it rebounded to 13 g/dl the next day prompting a consultation for Nephrology for management of acute kidney injury and hypercalcemia. A bone marrow biopsy ruled out for multiple myeloma, leading to consideration of other differentials. Parathyroid hormone (PTH) was appropriately low, and 25-Hydroxyvitamin D level was normal, but 1,25-Dihydroxyvitamin D was elevated at 108 pg/mL. This raised the suspicion of hypervitaminosis D due to granulomatous disease (sarcoidosis vs. infection). Detailed history revealed that the patient lived on a farm with various animals, including birds raising suspicion for an inhalational insult. CT scan of the lung that showed a left lung nodule. This was followed by a bronchoscopy that revealed high beta-D-glucan levels and fungal culture showed growth of Pneumocystis Carinii pneumonia. The patient was subsequently treated for PCP. After two months, his hypercalcemia was completely resolved. Discussion: Pneumocystis pneumonia is recognized for triggering a granulomatous response that stimulates the overproduction of 1,25-dihydroxyvitamin D, resulting in hypercalcemia and a range of complications, including AKI. Hypercalcemia associated with PCP proves resistant to standard treatments and should trigger a thorough patient history inquiry. In many cases, a comprehensive history and examination offer vital diagnostic insights even for non-immunocompromised patients.