SUN-582 Peripartum Central Hypothyroidism: A Case to Consider

Introduction: Hypothyroidism of central origin is fairly uncommon, estimated to occur in 1:20,000 to 1:80,000 in the general population (1). Misdiagnosed hypothyroidism during pregnancy can cause significant morbidity and mortality in the mother and the fetus. Here we present a case of central hypothyroidism diagnosed in a patient during pregnancy. Case presentation: A 31-year-old Hispanic female was found to have central hypothyroidism in her 7-month of pregnancy with low TSH, free T4 and TT3: TSH 0.4 (0.5 - 5.0), free T4 0.77, (0.6 - 0.78); She was started with Levothyroxine 50 mcg daily. Repeated bloodwork 4 weeks later still showed free T4 0.75 with TSH 0.057, consistent with central hypothyroidism, with symptoms of severe fatigue, muscle cramps, cold intolerance and weight gain. Unfortunately, she did not get the medical care from Endocrinology, and her LT4 dose was not optimized until 4 months after delivery of her child. She delivered a premature baby boy at 36 weeks by vaginal delivery, without severe complication but she was not able to produce breast milk after 6 weeks postpartum. The pituitary function was reviewed carefully: LH, FSH, IGF-1, and prolactin were within normal limits; morning cortisol was low but subsequently ACTH stimulation test was done with basal 5 and peak to 19 at 60 minutes. Pituitary MRI performed 6 months postpartum (11 months after she developed hypothyroidism) did not reveal pituitary swelling or tumors. Clear etiology for the hypothyroidism was not able to be identified in our patient, however, there was high suspicion for lymphocytic hypophysitis. Her hypothyroidism symptoms improved after her LT4 increased from 50 mcg to 75 mcg po daily, where TSH (0.89), free T4 (0.93) and TT3 (0.83) were normalized. Discussion: Although hypothyroidism is common, the etiology or management of central hypothyroidism during pregnancy is not familiar to OB/GYN or PCP. Delay or hesitation to refer to Endocrinology can lead to fetus risk like preterm delivery, intelligence development or even congenital deficits in body formation, in addition to mother effect like postpartum depression and lactation difficulty. The sharp awareness and prompt referral to a specialist needs to be improved with primary health taker for pregnant women. References: 1. Luca Persani; Central Hypothyroidism: Pathogenic, Diagnostic, and Therapeutic Challenges, The Journal of Clinical Endocrinology & Metabolism, Volume 97, Issue 9, 1 September 2012, Pages 3068-3078