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

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.