Levothyroxine Intake Timing During Ramadan in Patients With Hypothyroidism: A Systematic Review and Meta-Analysis of...

Daily medication is challenging in the Islamic holy month of Ramadan, particularly for patients on levothyroxine replacement therapy for hypothyroidism. Ramadan necessitates significant alterations to daily dietary habits and medication schedules, which may impact drug absorption and efficacy. This study aims to synthesize findings from existing research on the optimal timing of levothyroxine intake during Ramadan and to compare these results with established recommendations for nonfasting periods. By searching MEDLINE, PubMed, Google Scholar, Web of Science, and CENTRAL Cochrane Library databases from inception to May 2025, a systematic review and meta-analysis of randomized controlled trials (RCTs) and observational studies were conducted to evaluate the optimal timing of levothyroxine intake during Ramadan in patients with hypothyroidism. The study protocol was registered on PROSPERO (CRD420261284016). The primary outcome was thyroid-stimulating hormone (TSH) levels after Ramadan fasting. We used the standardized mean difference (SMD) with corresponding 95% confidence intervals (CIs) to synthesize results in the absence of heterogeneity. The risk of bias was assessed using Cochrane Risk of Bias 2 and Quality Assessment of Diagnostic Accuracy Studies 2 tools for RCTs and observational studies, respectively. We screened 214 records and included nine studies. A small but statistically significant increase was noted in post-Ramadan TSH levels compared with the prefasting levels (SMD = 0.29; 95% CI = 0.15-0.42; Z = 4.17; p < 0.001). However, most patients (79.8%) can maintain euthyroidism with different intake times (85.3%) if adherence is optimal. The results highlight various outcomes across different timings and the importance of patient adherence. Ultimately, rather than the timing of levothyroxine intake, adherence is the most likely factor determining the adequacy of thyroid function during and after Ramadan fasting.