Pneumocystis jirovecii Pneumonia Presenting as Severe Parathyroid Hormone-independent Hypercalcemia in a Renal Transplant Recipient

Abstract

Pneumocystis jirovecii pneumonia (PCP) is a well-recognized opportunistic infection in renal transplant recipients, typically presenting with subacute respiratory symptoms. Hypercalcemia as the predominant manifestation is rare and may result in diagnostic delay, particularly when pulmonary features are subtle. We report a renal transplant recipient who presented with severe parathyroid hormone-independent hypercalcemia, progressive allograft dysfunction, and minimal respiratory symptoms. Common causes of hypercalcemia, including tertiary hyperparathyroidism, Vitamin D excess, and malignancy, were excluded. Chest imaging showed bilateral ground-glass opacities, and bronchoalveolar lavage polymerase chain reaction confirmed PCP. Treatment with intravenous trimethoprim–sulfamethoxazole and supportive care led to normalization of calcium levels and improvement in graft function. This case highlights PCP as an underrecognized cause of hypercalcemia in transplant recipients.