Thyroxine Replacement Therapy during Ramadan Fasting: A Narrative Review

Abstract

Introduction Ramadan fasting-induced changes in eating and sleeping patterns pose a risk of influencing thyroid hormone levels. There is a recognition of the potential impact of fasting and feasting on levothyroxine (L-T4) absorption. Materials and Methods A narrative, nonsystematic literature review from two major medical online databases (PubMed and Google Scholar) from their inception to the search day (February 22, 2024). A relevant combined search term was used. The retrieved literature is narrated in a concise account. Results There is a relationship between metabolism and thyroid-stimulating hormone (TSH). This relationship contributes to transient metabolic disturbances that influence the pharmacodynamics and pharmacokinetics of various drugs, adding complexity to the management of hypothyroidism during Ramadan fasting. Several observational studies have studied the changes in thyroid function levels during unmodified L-T4 regimens. Experimental trials explored the impact on body weight, well-being, and thyroid functions when the timing of L-T4 administration changes. Findings are far from homogeneous due to different study protocols. A recent meta-analysis demonstrated a significant post-Ramadan increase in TSH levels among euthyroid patients. L-T4 timing points, encompassing pre-Iftar, post-Iftar, and pre-Suhoor, are associated with elevated TSH levels after Ramadan fasting. The emphasis on individualized L-T4 regimens during Ramadan fasting is underscored, with recommendations for patients to refrain from food for at least 3 hours before and 30 minutes after L-T4 intake to ensure optimal compliance by most experts. The association between adherence to L-T4 during Ramadan fasting and maintaining euthyroid status is highlighted, encouraging patients to follow prescribed regimens diligently. Modified dosing frequencies, such as weekly regimens, exhibit promising results, especially in patients grappling with compliance issues. Proactive consultations with physicians before Ramadan are needed to review the latest thyroid function test and make possible dose adjustments. Conclusion Managing hypothyroidism during Ramadan necessitates an understanding of medication timing, food-drug interactions, and prior regimens. Adherence, facilitated by flexibility, plays a critical role in achieving euthyroid status.