|Year : 2014 | Volume
| Issue : 2 | Page : 66-67
Management of primary hypothyroidism: Role of addition of levothyroxine at night
Santosh Kumar Singh
Practising, Endocrinologist, Patna, Bihar, India
|Date of Web Publication||31-Mar-2014|
Santosh Kumar Singh
301, Udaimaan Apartment, Opp. A. N. College, Boring Road, Patna - 800 001
Source of Support: None, Conflict of Interest: None
Background: Levothyroxine (LT4) is conventionally taken in the morning. Methods and Result: This retrospective study was done to assess the effect of addition of LT4 on thyroid hormone profile in primary hypothyroid patients. Conclusion: The study demonstrated significant improvement, which could be explained by greater bioavailability of LT4 and improved compliance.
Keywords: Hypothyroidism, levothyroxine, thyroid stimulating hormone
|How to cite this article:|
Singh SK. Management of primary hypothyroidism: Role of addition of levothyroxine at night. Thyroid Res Pract 2014;11:66-7
| Introduction|| |
Levothyroxine (LT4) is conventionally taken in the morning, about an hour before breakfast to prevent interference of its absorption by food or other medications.  Some studies have shown significantly improved thyroid hormone profiles in patients with primary hypothyroidism when LT4 was taken in late evening. ,, Majority of primary hypothyroid patients in India require 100 μg/d LT4. This retrospective study was done to assess the effect of addition of LT4 at night on thyroid hormone profile in patients requiring more than the usual 100 μg/d LT4 dose.
| Materials and Methods|| |
The patients were asked to take LT4 1 h before breakfast and night dose was to be taken 1 h before dinner, and advised to avoid food for 3 h prior to night dose.
| Results|| |
The results are shown in [Table 1].
| Discussion|| |
The addition of proportionately lower doses of LT4 at night provided significant improvement in thyroid hormone profile. Similar improvement was observed by simply splitting the morning dose into morning and night dose. The benefit could be due to increased bioavailability of LT4 at night owing to better absorption due to slower bowel motility at night and enhanced transport across small intestinal wall. Circadian rhythm of de-iodinases, inactivating pathways, binding proteins, and possible alteration in bioactivity of thyroid stimulating hormone could also contribute to increased efficiency of night dose LT4. , Bach-Huynh et al., have shown greater LT4 absorption in the morning compared to bed time dose.  This could be due to interference of LT4 absorption by food as morning dose was taken 1 h before breakfast but the evening dose was taken 2 h after dinner. It is recommended that LT4 should be taken 3 h after meal, although, another study has shown that the evening dose (2 h after dinner) is as efficacious as the morning dose (half-an-hour before breakfast). 
It is preferable to take LT4 1 h before breakfast and any food is to be avoided 3 h prior to night dose.
In conclusion, the addition of LT4 at night significantly improved thyroid hormone profile in patients with primary hypothyroidism.
| References|| |
|1.||Bach-Huynh TG, Nayak B, Loh J, Soldin S, Jonklaas J. Timing of levothyroxine administration affects serum thyrotropin concentration. J Clin Endocrinol Metab 2009;94:3905-12. |
|2.||Bolk N, Visser TJ, Kalsbeek A, van Domburg RT, Berghout A. Effects of evening vs. morning thyroxine ingestion on serum thyroid hormone profiles in hypothyroid patients. Clin Endocrinol (Oxf) 2007;66:43-8. |
|3.||Bolk N, Visser TJ, Nijman J, Jongste IJ, Tijssen JG, Berghout A. Effects of evening vs. morning levothyroxine intake: A randomized double-blind crossover trial. Arch Intern Med 2010; 170:1996-2003. |
|4.||Rajput R, Chatterjee S, Rajput M. Can Levothyroxine Be Taken as Evening Dose? Comparative Evaluation of Morning versus Evening Dose of Levothyroxine in Treatment of Hypothyroidism. J Thyroid Res 2011;2011:505239. |