Levothyroxine Dosing after Delivery in Women Diagnosed with Hypothyroidism During Pregnancy-A Retrospective, Observational Study

BACKGROUND: Pregnancy leads to profound alteration in thyroid function and dysthyroidism contributes to adverse pregnancy outcomes. Though the management of hypothyroidism during pregnancy is highlighted, the same is often neglected during postpartum. We have evaluated the postpartum levothyroxine (LT4) dose change in patients with new onset hypothyroidism. METHODS: We conducted this retrospective, observational study between 2014 and 2016 using the medical records of patients with new onset hypothyroidism during pregnancy. We included patients who continued with LT4 after delivery (as per predetermined protocol) and the availability of 2-year follow up record. We excluded patients who stopped LT4 and use of other drugs that affect the thyroid function tests (TFT) after delivery. The patients were divided into 2 groups for comparison [Group 1-Overt hypothyroidism (OH) and Group 2-Subclinical hypothyroidism (SCH)] based on the initial TFT reports. The data were analyzed using appropriate statistical methods and a P value of less than 0.05 was considered significant. RESULTS: A total of 159 women continued using LT4 after delivery and the final follow up data were available for 130 patients only. LT4 dose up titration was observed more in group 1 than in group 2 (P = 0.0336). In both the groups, the presence of goitre, thyroid autoimmunity and a repeat pregnancy are associated with increasing LT4 requirement. CONCLUSION: Majority of patients with OH during pregnancy require more than half of the final dose after delivery. Goitre and autoimmunity are associated with higher LT4 dose after delivery.