SAT229 Symptomatic Hypocalcemia In The Setting Of Crohn’s Disease With Severe Hypomagnesemia

Disclosure: K. Cuan: None. T. Reisman: None. Introduction: People with Crohn’s Disease (CD) are at risk for various nutritional deficiencies due to decreased oral intake, malabsorption, and increased intestinal losses. CD often causes a negative calcium balance, which does not usually cause hypocalcemia because the bones serve as a reservoir for calcium. However, symptomatic hypocalcemia may occur if a concurrent severe hypomagnesemic state is present. The factors resulting in hypocalcemia in patients with magnesium deficiency are impaired PTH secretion, PTH resistance, and vitamin D deficiency. Clinical Case: A 33-year-old man with CD and rheumatoid arthritis presented following a seizure with additional symptoms of hand cramping and facial twitching. He had previously undergone three small bowel resections and had a history of hypocalcemia due to malabsorption. Although this patient had previously been admitted due to a hypocalcemic seizure, he did not start oral calcium supplements at that time. No issues with magnesium were identified previously. On this encounter, he was found to have a corrected calcium (cCa) of 5.3 mg/dL, undetectably low magnesium at <0.7 mg/dL, normal phosphorus, 25-hydroxyvitamin D at 3.5 ng/mL, and an elevated intact PTH (iPTH) at 169 pg/mL. Aggressive intravenous calcium and magnesium repletion improved cCa to 7.4 mg/dL and magnesium to 2 mg/dL with no further seizure activity. He was discharged on calcium carbonate, calcitriol, and ergocalciferol. A month later, he presented to our endocrinology clinic asymptomatic but with a cCa of 6 mg/dL and magnesium at <0.7 mg/dL. Further biochemical workup revealed normal phosphorus, 25-hydroxyvitamin D at 7.9 ng/mL, and an inappropriately normal iPTH at 49 pg/mL. He was readmitted to the hospital where intravenous repletion improved cCa to 8.1 mg/dL and magnesium to 1.9 mg/dL. His recurrent hypomagnesemia was attributed to malabsorption. An increased dose of calcitriol and oral magnesium were added to his discharge medication regimen, in addition to his ergocalciferol and calcium carbonate. Three days later, he had a cCa level of 7.1 mg/dL as an outpatient. Conclusion: Patients with CD often have nutrient deficiencies, especially if they have had surgical resection within the intestinal tract. Our patient initially developed hypocalcemia from malabsorption, which was then exacerbated by the severely hypomagnesemic state. During his initial hospital encounter, the elevated iPTH level indicated PTH resistance. On his second encounter, the normal iPTH level suggested hypoparathyroidism. Given the relationship between magnesium and calcium homeostasis, addressing the hypomagnesemia eventually aided in achieving stabilization of serum calcium levels. Thus, in patients who are at risk for malabsorption and have recurrent symptomatic hypocalcemia, it is prudent to check magnesium levels as it can affect long term management of hypocalcemia. Presentation: Saturday, June 17, 2023