[Combined l-thyroxine and l-triiodothyronine replacement therapy in congenital hypothyroidism].

Abstract

INTRODUCTION:

L-thyroxine replacement therapy is the treatment of choice for hypothyroidism. Recently, several studies suggested to complete it with l-triiodothyronine in acquired hypothyroidism.

AIM:

To study the role of combined l-thyroxine and l-triiodothyronine therapy in special cases with congenital hypothyroidism.

METHOD:

Data of 16 patients (age: 11.9 ± 6.3 years; mean ± SD) are presented who had high serum free thyroxine values or even above the upper limit of reference range (21.16 ± 2.5 pmol/l) together with nonsuppressed TSH levels (15.7 ± 5.7 mIU/l), and therefore received l-triiodothyronine in completion (0.18 ± 0.09 μg/kg) once a day.

RESULTS:

The combined replacement therapy resulted in a rapid improvement of the hormone parameters (TSH: 4.2 ± 3.15 mIU/l; free thyroxine: 16.55 ± 2.4 and free triiodothyronine: 7.4 ± 1.8 pmol/l). The efficiency of this combined therapy proved to be more evident (TSH: 4.33 ± 3.2 mIU/l; free thyroxine: 16.85 ± 3.1 and free triiodothyronine: 6.4 ± 0.85 pmol/l) in 10 patients treated for a longer period of time (duration of treatment: 2.9 ± 2.0 years). The dose of thyroxine substitution decreased from 2.6 ± 0.9 to 2.18 ± 0.6 μg/kg/day), the ratio of these hormones was between 5:1 and 19:1 and the quotient of free fractions was normalized (3.8 ± 0.4→2.6 ± 0.3) during the replacement therapy.

CONCLUSIONS:

According to the observation of the authors a serious disturbance of feed-back mechanism may develop in some (>5%) children with congenital hypothyroidism (increased TSH release despite elevated free thyroxine level) after normal function of the feed-back system for years. Hormone parameters of these patients improve, then become normal on combined therapy supporting the rationale for this treatment method.

• Authors: Ferenc Péter, Agota Muzsnai
• Journal: Orvosi hetilap (Orv Hetil) Vol. 154 Issue 19 Pg. 738-44 (May 12 2013) ISSN: 0030-6002 [Print] Hungary
• Vernacular Title: Kombinált l-tiroxin és l-trijód-tironin hormonpótlás congenitalis hypothyreosisban.
• PMID: 23649638 (Publication Type: English Abstract, Journal Article)

Chemical References

• Triiodothyronine
• Thyrotropin
• Thyroxine

Topics

• Congenital Hypothyroidism (diagnosis, drug therapy, epidemiology, metabolism)
• Drug Therapy, Combination
• Feedback, Physiological
• Female
• Hormone Replacement Therapy (methods)
• Humans
• Hungary (epidemiology)
• Infant, Newborn
• Male
• Retrospective Studies
• Thyroid Function Tests
• Thyrotropin (blood, metabolism)
• Thyroxine (therapeutic use)
• Triiodothyronine (therapeutic use)