Levothyroxine Administration Techniques Audit and Utility of its Assessment at Each Visit: A Hospital-based Mixed Model Study

Abstract Introduction: Levothyroxine has a narrow therapeutic index, with many factors affecting bioavailability. Overtreatment and undertreatment of hypothyroidism are common in clinical practice. Methods: In this study, we assessed the prevalence of incorrect levothyroxine administration technique (ILAT) in clinical practice and the impact of correction on follow-up. The study had two phases. The first phase was that all consecutive patients with primary hypothyroidism on treatment for at least 1 year with a minimal dose of 25 mcg were enrolled, and ILAT was assessed. Second phase: Participants with abnormal Serum TSH or ILAT were followed on the correct technique for euthyroidism. Results: Among 444 participants (358 female and 86 male) at baseline, 46.2% had raised TSH, 41.3% were euthyroid, and 12.4% had iatrogenic thyrotoxicosis. The levothyroxine administration technique (LAT) was incorrect in 77.4% of participants. In participants with raised Serum TSH at baseline with incorrect LAT, on correction of the technique, the levothyroxine dose decreased in 26.3%, no dose change was required in 14.9%, and only 58.8% required dose escalation. Even among euthyroid at baseline with incorrect LAT, 64.4% needed dose reduction to remain euthyroid on correction of the technique. Among participants with suppressed TSH at baseline and ILAT, the levothyroxine dose at baseline was 97.5 ± 28.7 mcg/day, and with correction of the technique, the final dose was 71.1 ± 23.9 mcg/day. The decrease in dose was statistically significant ( P = 0.001). Conclusion: Ensuring the correct administration technique at each contact, especially before any dose adjustment, is essential to prevent suboptimal or overtreatment in primary hypothyroidism.