BMJ  2003;327:E216 (4 October), doi:10.1136/bmjusa.03040004 (published 6 May 2003)

BMJ USA: Letter

RAPID RESPONSES FROM BMJ.COM

Restoration of serum TSH to within the reference range should be the goal of replacement therapy

Following is an edited excerpt from one of the Rapid Responses generated by this article, which can be read in their entirety at http://bmj.com/cgi/eletters/326/7384/311 — Editor

From BMJ USA 2003;April:204

Editor — Meier and colleagues conclude that judicious initiation of thyroxine treatment in overt hypothyroidism should be guided by clinical and metabolic presentation and thyroid hormone concentrations and not by serum TSH concentrations.

This conclusion appears to contradict overwhelming evidence that serum TSH represents the most sensitive marker of primary hypothyroidism. Furthermore, it is not supported by the findings of the study. The cohort was a selected group of 49 patients with significant hypothyroidism (mean serum TSH concentration >40 µIU/mL) and the study utilized a series of poorly specific and sensitive markers of thyroid status. There was no control for duration of hypothyroidism, an important factor determining the clinical symptoms and signs.

Whether these data can be extrapolated to patients on thyroxine therapy is questionable. The accompanying editorial by Toft and Beckett (p 187) states that some patients on thyroxine replacement continue to have symptoms despite restoration of normal TSH concentrations and that exogenous subclinical hyperthyroidism is less harmful than endogenous subclinical hyperthyroidism. Few, if any, data support this view. This statement conflicts with increasing evidence that excessive thyroxine replacement results in adverse symptoms and quality of life scores, increased bone loss, and adverse cardiovascular outcomes. It is our belief that restoration of serum TSH to within the reference range should be the goal of replacement therapy. If symptoms persist despite adequate replacement then an alternative explanation should be sought.

¹ Royal Free Hospital Trust mark.vanderpump{at}royalfree.nhs.uk, ² University of Birmingham, Birmingham, UK

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