PSAT220 Severe Vitamin D Deficiency and Hypocalcemia during Pregnancy Masquerading as Thyroid Storm

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Abstract Background Hypocalcemic tetany in young female patients is a clinical entity that is well-described in literature. Here we present a potentially life-threatening case of hypocalcemia secondary to severe Vitamin D deficiency and hyperemesis gravidarum mimicking thyroid storm. Case Presentation A 22-year-old Caucasian woman at 21 weeks gestation was transferred to our hospital for suspected thyroid storm with TSH <0.01 mIU/L (0.05-5.7). She had no history of nor risk factors for thyroid disease and presented with severe agitation, hallucinations, and muscle spasms after weeks of vomiting and poor oral intake. In the ambulance her temperature was 106.6F (rectal) and she was tachycardic (216/minute). EKG revealed ventricular arrhythmia with QTc 532 ms. EMS interventions included unsuccessful cardioversion with 100J and 300mg IV amiodarone bolus. In the ED, serum calcium level was 5.9 mmol/L (8.4-10.2), albumin 2.8 g/dL (3.3-4.5), magnesium 1.0 mmol/L (1.7-2.3), potassium 3.1 mmol/L (3.5-4.8), lactic acid 9.5 mmol/L (0.5-2.2), Free T4 1.36 ng/dL (0.58-1.65), troponin 2.21 ng/ml (0.00-0.03), β-hcg 48,775 mIU/ml, CK 9960 U/L (0-188), AST 171 U/L (8-34), ALT 45 (0-24). She received IV calcium gluconate, aggressive IV hydration and electrolyte repletion. Free T3 was drawn prior to initiating empiric thyroid storm treatment (hydrocortisone, propylthiouracil) returned at 3.8 pmol/L (2.5-3.9). Thyroid storm was further ruled out with negative antibodies for TPO and TSI and ultrasound revealing normal-sized gland without nodules and with normal vascularity. Hydrocortisone and Thionamide therapy were discontinued. The patient had rapid improvement in mentation and vitals with continued hydration and electrolyte repletion. 25-hydroxy-Vitamin D level was undetectable and PTH 118 pg/mL (12-88), consistent with secondary hyperparathyroidism. Celiac disease was ruled out with negative tissue transglutaminase IgA and IgG. At her follow-up clinic visit, symptoms had resolved with calcium and Vitamin D supplementation. Discussion Though a common phenomenon in pregnant women, metabolic derangements due to hyperemesis gravidarum can be quite severe and/or life-threatening, as in our case. Literature search revealed an isolated case of hyperemesis gravidarum presenting with severe electrolyte derangement and subsequent paraparesis which resolved after vitamin D and calcium supplementation. Hyperthyroidism is typically associated with hypercalcemia in the Western population. This patient's presenting features of hyperpyrexia, malignant cardiac arrhythmia, hepatitis, and altered mentation were reminiscent of thyroid storm and could easily be attributed to such in a pregnant patient with suppressed TSH. This could lead to continued use of thionamide and further hepatic damage. Thus, it is prudent to consider hypocalcemia in the differential diagnosis of thyrotoxicosis-like presentation, particularly in pregnant patients. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.