7761 Unmasking The Uncommon: A Case Of Primary Adrenal Insufficiency Presenting As Severe Hypercalcemia

Abstract

Abstract Disclosure: A. Misbah: None. Z. Al-Hiti: None. A. Saleh: None. M. Joda: None. K. Rajamani: None. Adrenal insufficiency is a recognized but uncommon cause of hypercalcemia. The exact mechanism remains unknown; however, it is thought to be a combination of the hypovolemic state in adrenal insufficiency leading to decreased urinary clearance, as well as increased bone resorption. We present a case of primary adrenal insufficiency presenting with severe hypercalcemia. A 41 year old female with a past medical history of osteopenia, recently diagnosed postural orthostatic tachycardia syndrome (POTS), and hyponatremia attributed to SIADH presented with complaints of weakness and poor oral intake. She also reported a history of nausea, vomiting, weight loss, fatigue, and dizziness, for the last few months. She reported feeling well prior to a COVID-19 infection a few months back. At presentation, she was hypotensive with a blood pressure of 70/50 mmHg, while her other vital signs were stable. She appeared ill, and was noted to have dry oral mucous membranes. There was no increased pigmentation noted on exam. Initial laboratory evaluation revealed sodium of 130 (135-145 mmol/L), potassium of 5.3 (3.5-5.1 mmol/L), and creatinine of 1.7 (0.5-0.8 mg/dL). She had severe hypercalcemia with a calcium level of 15.5 (8.3-10.6 mg/dL) and had a blood glucose level of 53 (70-100 mg/dL). Venous blood gas indicated metabolic acidosis. Morning cortisol was low at 1 (3-23 ug/dL). Serum ACTH was elevated at 775 (0-46 pg/mL). Cosyntropin stimulation test confirmed primary adrenal insufficiency. She underwent work-up for hypercalcemia, which revealed a suppressed PTH, normal levels of PTHrP, vitamin D, and vitamin A. Serum and urine protein electrophoresis was normal. She was initially managed in the ICU and received aggressive fluid resuscitation. She was started on stress dose of hydrocortisone, which was then tapered to physiological doses of oral hydrocortisone and fludrocortisone. Subsequent improvements were observed in blood pressure, laboratory abnormalities, and normalized serum calcium levels. She was discharged home on hydrocortisone and fludrocortisone. On follow-up, she was doing well with the resolution of her symptoms. This case highlights the importance of recognizing adrenal insufficiency as one of the causes of hypercalcemia. Although hypercalcemia as a consequence of adrenal insufficiency is well-documented, the exact prevalence is not known but is estimated to be around 6%. After excluding more common diseases such as primary hyperparathyroidism and malignancy, the possibility of adrenal insufficiency should be considered as a cause of hypercalcemia. Treatment involves hormone replacement as well as hydration, bringing resolution to symptoms. Her presentation was unique, also due to the fact that her initial symptoms were diagnosed as POTS as well as SIADH. Given the onset of symptoms after a COVID-19 infection a few months ago, there could also be a potential link between the two. Presentation: 6/3/2024