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The American Thyroid Association recommends taking levothyroxine consistently, "either 60 minutes before breakfast or at bedtime." However, clinicians typically opt to recommend taking levothyroxine on an empty stomach, rather than offering the option of bedtime or with breakfast. Many patients find it cumbersome to take levothyroxine in the morning without food. A meta-analysis was performed to evaluate the effects of taking levothyroxine (LT4) before breakfast (BB) vs. with breakfast (AB) on thyroid function tests in our included four clinical trials. Four randomized controlled trials involving 243 patients were retrieved from PubMed, according to established inclusion criteria. The Standard Mean Difference (SMD) of thyroid-stimulating hormone (TSH), free T4 (FT4), and free or total T3 (F/TT3) with their 95% confidence intervals between AB vs. BB were calculated. Random effect or fixed-effect model was used based on heterogeneity significance. Then a subgroup analysis of liquid levothyroxine and tablet levothyroxine was performed. Sensitivity analysis and publication bias detection were performed. All statistical analysis was performed using RevMan software (v5.4; Cochrane library) and R Core Team (2016, Vienna, Austria), and all p-values were two-tailed, and the significance level was 0. 05. No statistically significant differences of TSH (Mean 1.45-3.74 vs. 1.26-3. 00, SMD 0.25; 95% CI: -0. 06, 0.56; p=0.11, I2=65%), FT4 (Mean 1. 03-1.35 vs. 1. 02-1.24, SMD 0.14; 95% CI: -0.33,0.62; p=0.55, I2=78%), and F/TT3 (SMD -0. 06; 95% CI: -0.28,0.15; p=0.57, I2=0%) between AB vs. BB were found. The subgroup analysis showed that no statistically significant difference of TSH between AB vs. BB when patient took liquid form of levothyroxine (1.45-2.59 vs. 1.26–3. 00; SMD=0. 03; 95% CI: -0.21, 0.27; p=0.81, I2=0%). Although TSH was significantly higher with AB vs. BB when patient took tablet form of levothyroxine (2.89-3.74 vs. 1.54 -1.9; SMD=0.64; 95% CI: 0.24, 0.103; p=0. 001, I2=49%), TSH was within normal limits in both groups. This meta-analysis demonstrates that TSH of patients taking levothyroxine with breakfast is non-inferior to those taking it before breakfast. Although AB group taking levothyroxine by tablet has a significantly higher TSH level than the BB group, both groups have well-controlled levels. Limitations of this study include limited sample size and number of studies. It also was unable to differentiate patients with hypothyroidism from benign or malignant diseases. We also were not able to assess adherence to the prescribed regimen. Patient satisfaction and adherence with treatment may be improved by letting patients know to take LT4 consistently at a time of their choice. Presentation: No date and time listed |
