SAT244 Hypercalcemia Induced By Inconspicuous Histoplasmosis Infection

Disclosure: M. Alkhathlan: None. Y. Li: None. A. Siddiqui: None. S. Goud: None. Background: Hypercalcemia is a common condition with a variety of etiologies. In general, it can be categorized as either parathyroid hormone (PTH) dependent or independent. In those with non-PTH mediated hypercalcemia, elevated 1, 25 vitamin D is one of the causes and among pathologies behind it are sarcoidosis, malignancy, and to less extent infectious process. An important determinant in the management of elevated 1,25vitD is to identify the source of 1,25vitD overproduction as the choice of treatment can affect the outcomes and increase the risk of mortality. Clinical Case: Our patient is an 81-year-old man who had been admitted to the hospital for nonspecific fatigue and weakness for two months. He was discharged from another hospital with similar complaints without resolution. At the time of admission, he was noted to have elevated total calcium 12.5 mg/dL (8.4-10.2) with albumin 3.0 g/dL (3.5-5.2), subacute kidney injury with creatinine 3.46 mg/dL (0.7-1.3), suppressed parathyroid hormone (PTH) and markedly elevated 1,25-dihydroxy vitamin D (1,25OH2D) 128 pg/mL (19.9-79.3). His calcium and kidney function were normal 4 months ago. The hypercalcemia was refractory to intravenous fluid, loop diuretic or calcitonin administration. Extensive workup eventually revealed disseminated histoplasmosis infection with blood and urine positive for histoplasmosis antigens. Bone marrow aspiration showed scattered non-necrotizing granulomas. With antifungal treatment, his calcium level returned to the normal range in two weeks (8.9 mg/dL) and was maintained in the normal range. Conclusion: Hypercalcemia is a rare presentation of histoplasmosis. Pubmed keyword search of hypercalcemia and histoplasmosis returned 18 clinical case reports from 1977 to 2021. The case review showed a striking similarity in atypical clinical presentation and diagnosis challenges. Hypercalcemia is most developed in histoplasmosis disseminated cases with elevated 1,25vitD levels and pathology identification of granulomas in some of the cases. With successful antifungal treatment, patients will have prompt recovery of hypercalcemia. Steroid treatment is a well know and effective treatment by suppressing 1-alpha hydroxylation of 25-vitD. However, treatment with steroids before establishing diagnosis due to Inconspicuous presentations or delay in diagnosis may lead to mortality quickly. Presentation: Saturday, June 17, 2023