Subclinical Hypothyroidism Balancing Act: Knowing When to Treat

Tyler C. Drake, MD

Disclosures

October 03, 2019

Editorial Collaboration

Medscape &

Discussion

It can be a challenging situation when patients come into the visit already believing that they have a problem with their thyroid and expecting treatment. Symptoms of hypothyroidism are vague and nonspecific, making it difficult to treat based on symptoms alone. It is important to consider other nonthyroid causes of the patient's symptoms, whether there is an underlying thyroid pathologic condition, and whether laboratory test abnormalities are likely to be temporary or permanent.

In this case, repeating the TSH test to confirm a persistent elevation is key because the TSH level will often normalize without treatment. In fact, 46% of patients with a TSH level < 7 mU/L will have a normal level within 2 years.[5] Also, evaluating for underlying autoimmune thyroid disease with a TPO antibody test will help determine whether there is an underlying pathologic condition. Having positive results for TPO antibodies does not guarantee this patient will progress to overt hypothyroidism, but it would make it more likely and build a stronger case to start treatment.

If her TSH level remains elevated on repeat testing and her TPO antibody level is elevated, I would consider treatment. Conversely, if her TSH level remains only mildly elevated and her TPO antibody test result is negative or if her TSH level normalizes, I would evaluate for other causes of her fatigue and not prescribe levothyroxine.

Given her concerns and symptoms, I would not wait 1 year to repeat the test. A thyroglobulin panel is unnecessary because this is used for surveillance in patients with thyroid cancer after thyroidectomy.

Conclusion

Most often, subclinical hypothyroidism does not require treatment, and recent studies have shown no clinical benefit to treatment in older adults. I do not suggest using a TSH level of 10 mU/L as the cutoff for treatment because this does not address the underlying cause. It's simply a knee-jerk reaction to an abnormal laboratory value and commits your patients to lifelong treatment.

When trying to decide when to treat subclinical hypothyroidism, ask yourself, "Is there an underlying pathologic condition or disease of the thyroid gland?" and "Is this a persistent or temporary problem?" By using patient age, family history, symptoms, thyroid antibody status, and multiple TSH values, you can answer these questions and make individualized decisions for your patients.

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