Subclinical Hypothyroidism Balancing Act: Knowing When to Treat

Tyler C. Drake, MD

Disclosures

October 03, 2019

Editorial Collaboration

Medscape &

Discussion

Here we have a young, healthy female with a strong family history of hypothyroidism and symptoms consistent with hypothyroidism. Her mother and sister most likely have Hashimoto disease, and because autoimmune diseases tend to run in families, our patient probably has the disease as well.

Given her young age, symptoms, and likely underlying pathologic conditions, I would recommend treatment at this time. Although she could also be in the recovery phase of subacute thyroiditis, nothing in her history suggests this is the case. If she had described a recent viral illness or anterior neck pain, repeating the TSH test in 3 months would be appropriate. I often request TPO testing to confirm the presence of antibodies, but in this case, I would recommend treatment regardless of the results. Finally, a thyroid ultrasound has little utility in the evaluation of functional thyroid disease and should be reserved for evaluating suspected thyroid nodules.

Women of childbearing age with subclinical hypothyroidism should be more aggressively treated, given the potential for future pregnancies. During pregnancy, thyroid hormone production increases by 30%-50%, and in the presence of underlying thyroid pathologic conditions, the concern is that this increase will not occur, affecting fetal development. The American Thyroid Association recommends treating subclinical hypothyroidism with levothyroxine during pregnancy regardless of TPO antibody status, although it is a strong recommendation if the TPO test result is positive and a weak recommendation if the TPO test result is negative and the TSH level < 10 mU/L.[4] Pregnancies are not always planned, so I favor treating subclinical hypothyroidism in young women.

Case #3: The Internet Search

A 51-year-old woman recently started a new job that is very stressful and has since felt more fatigued. When searching online for causes of fatigue, she learned about thyroid disease and now wonders if she has Hashimoto disease. She has no complaints other than fatigue and sleeping poorly. She denies cold intolerance, constipation, depression, or lower extremity edema, and she has no family history of thyroid disease. You check her TSH level at her request, which is elevated at 5.5 mU/L (normal range, 0.4-4.5 mU/L).

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