Figure 2. Deiodinases. While the deiodinases have not yet been crystallized, protein modeling indicates that they share a common general structure composed of a.
We observed cases in which TSH levels improved markedly after changing the administration time of l-thyroxine to the late evening. We therefore conducted a pilot-study to investigate whether l-thyroxine administration at bedtime improves TSH and thyroid hormones, and whether the circadian rhythm of TSH remains intact.
Clin Chem. 1996;. Faglia G, Beck-Peccoz P, Piscitelli G, et al. Inappropriate secretion of thyrotropin by the pituitary. Horm Res. 1987;. Ohzeki T, Hanaki K, Motozumi H, et al. Refractoriness at peripheral and pituitary receptors in general and pituitary types of thyroid hormone resistance.
Free T4 was higher in treated central and primary hypothyroidism than in euthyroidism. Age, sex and BMI did not affect the free T3 to free T4 ratio. CONCLUSIONS : Treated patients with central hypothyroidism had a lower free T3 to free T4 ratio, similar free T3 levels and higher free T4 concentrations than euthyroid controls.
The standard treatment of hypothyroidism (central and primary) consists of thyroxine (T4) administration alone. However, the normal thyroid gland produces a small proportion of triiodothyronine (T3) directly into the circulation. AIM: We aimed to study the free T3 to free T4 ratio in treated central hypothyroidism compared with euthyroidism and treated primary hypothyroidism.
At the same time, the circadian TSH rhythm stays intact. Our findings are best explained by a better gastrointestinal uptake of l-thyroxine during the night.
1. Endocrinol Nutr. 2011 Jan;58(1 9-15. doi: 10.1016/j.endonu. Epub 2010 Dec 31. Serum free triiodothyronine (T3) to free thyroxine (T4) ratio in treated.
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Horm Metab Res. 1992;. Refetoff S, Weiss RE, Usala SJ. The syndromes of resistance to thyroid hormone. Endocr Rev. 1993;. Brent GA, Hershman JM, Braunstein GD. Patients with severe nonthyroidal illness and serum thyrotropin concentrations in the hypothyroid range.
OBJECTIVE : Standard drug information resources recommend that l-thyroxine be taken half an hour before breakfast on an empty stomach, to prevent interference of its intestinal uptake by food or medication.
1. Clin Endocrinol (Oxf). 2007 Jan;66(1 43-8. Effects of evening vs morning thyroxine ingestion on serum thyroid hormone profiles in hypothyroid patients).
PATIENTS : We investigated 12 women treated with l-thyroxine because of primary hypothyroidism, who used no medication known to interfere with l-thyroxine uptake. MEASUREMENTS : Patients were admitted to hospital and blood samples were obtained at hourly intervals for 24 h via an indwelling catheter.