How to identify subclinical hypothyroidism

Learn how to identify subclinical hypothyroidism.

Tracy Tylee, MD
Tracy Tylee, MD
30th Mar 2018 • 2m read

Sometimes spotting a case of hypothyroidism can be tricky! In this video from our Thyroid Disease Masterclass, you'll learn how to interpret lab findings to confidently diagnose a case of subclinical hypothyroidism.

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Master the management of thyroid disease. In our Thyroid Disease Masterclass, Dr Tracy Tylee–Clinical Assistant Professor of Endocrinology at the University of Washington–will review the pathophysiology of thyroid dysfunction, discuss the interpretation of thyroid tests, explain how pregnancy and certain medications can alter thyroid function, and evaluate the best treatment options.

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Video Transcript

[00:00:00] Occasionally, patients will have an elevated TSH but normal thyroid hormone levels. This is a condition known as subclinical hypothyroidism. There are multiple causes of this. One, early Hashimoto's thyroiditis or resolving thyroiditis, for patients on therapy taking inadequate doses of levothyroxine will result in labs such as this, and patients who have poor compliance with their medication. In fact, poor compliance is one of the primary reasons patients will present with labs such as this.

[00:00:30] You can see a patient on levothyroxine therapy who stops her medication for whatever reason. Their thyroid hormone levels will drop with a corresponding increase in TSH levels. When the patient restarts their medication, their T4 levels recover fairly quickly but the TSH does lag behind. So, if labs are checked during this time period, they will appear to have subclinical hypothyroidism. For patients on levothyroxine, it's always a good idea to ask how they were taking their medication and ensure that they are compliant. One of the concerns with subclinical hypothyroidism is,

[00:01:00] which patients are likely to progress to overt hypothyroidism and thus, may require a bit closer follow-up. Patients who have a TSH greater than ten are at a higher risk of progressing to hypothyroidism, as our female patients. Patients who are on a high iodine diet are more likely to develop hypothyroidism, and people with autoimmune thyroid disease or positive TPO antibodies. For patients with TPO antibodies, they're twice as likely to develop hypothyroidism as patients who have negative TPO antibodies.

[00:01:30] So, do require a closer follow-up in the long term. Some patients with subclinical hypothyroidism need treatment despite normal thyroid hormone levels. It's typically recommended that pregnant women or women who are interested in pregnancy are started on treatment to normalize their TSH levels as well elderly patients with a TSH greater than ten should be started on levothyroxine therapy as well.