Session: MON 437-470-Non-neoplastic Thyroid Disorders
Poster Board MON-439
Methods: We designed a prospective, randomized study comparing 2 methods of LT4 dose adjustment in hypothyroid women during pregnancy for efficacy in maintaining goal TSH. Women age 18-45 with hypothyroidism of any etiology, who achieve pregnancy naturally, have pre-pregnancy TSH≤ 4.5 mIU/L and are ≤10 weeks’ gestation are eligible. Subjects are randomized to either Group 1) empiric LT4 dose adjustment, in which LT4 dose is increased by 2 pills/week at enrollment followed by adjustments by #pills/week, or Group 2) individualized LT4 dose adjustment based on TSH at enrollment, followed by adjustments by #mcg/day. TSH monitoring is performed q2 wks in Trimester (T)1 and T2, and q4 wks in T3. In both groups, LT4 dose is adjusted using algorithms designed to maintain TSH≤2.5 uIU/mL in T1, 0.5-2.5 uIU/mL in T2, and 0.5-3.0 uIU/mL in T3. Student’s T-tests were performed to examine differences between groups, P<0.05.
Results: To date, 13 women (G1, n = 6; G2, n = 7) have enrolled and 8 (61.5%, G1, n =4; G2, n =4) have completed pregnancy. All pregnancies are singleton except 1 twin pregnancy in G2. Etiology of hypothyroidism is not different between groups (thyroid cancer: G1, n=4, G2, n=3; primary hypothyroidism: G1, n=2; G2, n=3). There are no differences between groups in maternal age (33±3.0 yrs, G1 vs 33±1.7 yrs, G2), week of gestation (7±2 wks, G1 vs 5±1 wks, G2), or LT4 dose (109±36 mcg/day, G1 vs 123±25 mcg/d, G2) at enrollment. TSH at enrollment was lower in G1 (0.43mIU/L±0.4, G1 vs 1.01±0.6, G2, P=0.067), trending toward significance. There were no differences in free T4 or total T3 (ng/dl) between the groups at enrollment (fT4: 1.5±0.3, G1 vs 1.6±0.2, G2; TT3: 117±21, G1 vs 106±28 ng/dl, G2). TSH throughout the study period was higher in G2 (1.1±1.4 mIU/L, G1 vs 1.7±1.8 mIU/L, G2, P<0.05). % of TSH values outside goal range per participant (22%±21, G1 vs 33%±24, G2) and % of TSH values requiring LT4 dose changes per individual (41.5%±24, G1 vs 46%±14.5, G2) were not statistically different between groups.
Conclusion: Frequent (q2-4 wk) monitoring of thyroid function during pregnancy is crucial to maintain optimal maternal TSH levels. Our data suggest that empiric and individualized LT4 dose adjustment strategies using algorithms to maintain trimester-specific goal TSH are equally effective in the management of hypothyroid women during pregnancy.
Nothing to Disclose: GP, KB, JJ, UPR, SDS
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