Should the dose of levothyroxine be changed in hypothyroidism patients fasting during Ramadan?

Muslims worship by fasting from predawn (suhoor) until sunset (iftar) for 30 days in the religious month of Ramadan. In addition to prolonged hunger, patients fasting with a diagnosis of hypothyroidism take their doses of levothyroxine (LT4) outside of daytime fasting hours. The purpose of our study is to compare the values of hypothyroid patients which have been obtained through thyroid function tests before and after Ramadan.

Ninety-seven patients; ranging from 18 to 65 years old, who were followed with a diagnosis of hypothyroidism, who fasted during Ramadan, and who had no change of their LT4 dose for at least 6 months were included in the study.

The median serum thyroid-stimulating hormone (TSH) level of patients prior to fasting was 2.19 mIU/L, while median serum TSH after fasting was 2.73 mIU/L. Serum TSH values after Ramadan increased significantly compared to those prior to Ramadan (P = 0.004).

Our study demonstrates a significant increase in serum TSH levels after Ramadan but no significant change in serum free thyroxine (fT4) levels in hypothyroidism patients who are fasting. It may be appropriate to take precautions by making a small increase in LT4 dose before Ramadan in some hypothyroid patients wishing to fast.