Subclinical Hypothyroidism: Why Wait to Treat?

December 31, 2006

In his article, “Subclinical Hypothyroidism: When to Treat, When to Watch?”(CONSULTANT, April 1, 2004, page 533), Dr Vahab Fatourechi notes that thereis some evidence that subclinical hypothyroidism has adverse effects on cardiovascularfunction that may contribute to left ventricular systolic dysfunction with effort.

In his article, "Subclinical Hypothyroidism: When to Treat, When to Watch?"(CONSULTANT, April 1, 2004, page 533), Dr Vahab Fatourechi notes that thereis some evidence that subclinical hypothyroidism has adverse effects on cardiovascularfunction that may contribute to left ventricular systolic dysfunction with effort.Yet he advises waiting for further studies to confirm these data before adoptinga policy of prescribing thyroid replacement therapy for all patients with subclinicalhypothyroidism. Why is it necessary to wait for more evidence to come inwhen titrated thyroid therapy is relatively benign?-- Sam Gammenthaler, MD
  &nbsp Hendersonville, NC
The question you pose is an important one. The view that all patientswith abnormally high thyroid-stimulating hormone (TSH) levelsshould be treated is shared by some investigators, such as Biondi andcolleagues.1 However, as I mentioned in my article, the data on thisissue are not conclusive; some reports do not confirm that TSH levelsbetween 5 and 10 mIU/L are a risk factor for heart disease. A significant numberof patients who are receiving thyroxine therapy are overtreated, and a suppressedTSH level has its own adverse effects. Thus, a uniform recommendationof therapy for all patients cannot be made.As a general rule, before any intervention can be recommended, theremust be adequate evidence and demonstration of benefit. In patients with minimallyelevated TSH levels, no data exist for the latter. Until conclusive studiesclarify the issue, we recommend individualization and the use of physicianjudgment and consideration of patient preference when determining therapyfor patients with TSH levels between 5 and 10 mIU/L.2-- Vahab Fatourechi, MD
  &nbsp Professor of Medicine
  &nbsp Division of Endocrinology, Diabetes, Nutrition,   &nbsp and Metabolism
  &nbsp Mayo Clinic College of Medicine
  &nbsp Rochester, Minn

References:

REFERENCES:
1.

Biondi B, Palmieri EA, Lombardi G, Fazio S. Effects of subclinical thyroid dysfunction on the heart.

AnnIntern Med.

2002;137:904-914.

2.

Surks MI, Ortiz E, Daniels GH, et al. Subclinical thyroid disease: scientific review and guidelines for diagnosisand management.

JAMA.

2004;291:228-238.