MON-586 Practice Variation in the Management of Subclinical Hypothyroidism During Pregnancy: Results From a National Survey of Endocrinologists in the US

Background: Evidence regarding subclinical hypothyroidism (SCH) effects on pregnancy and the benefits of levothyroxine (LT4) treatment is inconsistent. The American Thyroid Association (ATA) Guidelines for the management of thyroid diseases in pregnancy were published in 2017; the impact of these guidelines on clinical practice remains uncertain. Aim: To conduct a national survey among endocrinologists studying knowledge and perception regarding SCH diagnosis, treatment and impact on pregnancy. Methods: An online survey was sent by email invitation to endocrinologists who are active members of the Endocrine Society in the U.S. (n=5914). The questionnaire included demographic data and clinical scenarios with multiple choice questions to assess diagnostic evaluation, initiation of therapy, and follow up in pregnant women with SCH. Results: The survey was completed by 154 endocrinologists (9/5/18-10/31/18). On average each clinician had treated 5 (IQR 3-10) women with SCH in the past 6 months. The 2017 ATA guidelines were reviewed by 75% of whom 52% consider that these guidelines actually changed their clinical practice. Universal screening is done by 53%, 31% screens when there are associated risk factors for thyroid disease (e.g. clinical symptoms, family history, etc.) and 16% never screens. For the diagnosis of SCH, only 25% uses a TSH>4.0 mIU/L and 5.8% a population-based cutoff as recommended by ATA, while the most used cutoff was TSH>2.5 mIU/L (52%). Following ATA guidelines, 87% would immediately treat a woman with a 1(st) trimester TSH>4.0 mIU/L and TPO-Abs+ (strong recommendation) vs. 50% if TPO-Abs– (weak recommendation), followed by the option of repeating TSH within a month in 12% and 45% respectively. If a woman had TSH between 2.5-4.0 mIU/L, 58% would treat her if TPO-Abs+ (weak recommendation) vs. 17% if TPO-Abs- (no recommendation), followed by the option of repeating TSH within a month in 39% and 55% respectively. We found similar practices for the treatment of women in the 2(nd) trimester with the same clinical and laboratory characteristics. Clinicians reported considering the following factors for LT4 treatment decision: TSH level, TPO-Abs, history of miscarriages, and guidelines recommendations. Interestingly, 70-80% of the clinicians who would start LT4, consider treatment would have a small impact (10-20% reduction) or very small impact (<10% reduction) on maternofetal complications regardless the clinical scenario. Only 50% of the clinicians take into consideration the patient’s preferences and 19% the side effects related to LT4 use. Conclusions: Despite recently updated guidelines, there is still a wide variation in the clinical practice regarding the diagnosis and management of SCH in pregnancy. Although LT4 is frequently used as the treatment for SCH in pregnancy, the expected risk reduction is small, and patient’s preferences are often disregarded.