SCH: When should you stop thyroxine?: Dr Aneesh Basheer
M3 India Newsdesk Nov 01, 2021
While clinically significant and deficiency of thyroid hormones being quite easy to diagnose, many individuals do not have florid symptoms and signs. Here we bring to you a medical analysis of studies to understand when thyroxine should be stopped in those who receive thyroid hormone supplementation.
To stop or not to stop - are we close to an answer?
Hypothyroidism is a common disease predominantly affecting women. In some patients, hypothyroidism is suspected or diagnosed during evaluation for other conditions, routine health checks and pre-operative assessment.
Subclinical hypothyroidism is characterised by elevated levels of Thyroid-Stimulating Hormone (TSH), usually between 5 and 10 mU/L and normal free thyroid hormone levels in the absence of typical symptoms.
Available data and consensus do not recommend supplementing thyroid hormone for subclinical hypothyroidism unless the patient is pregnant. However, a significant number of patients with subclinical hypothyroidism are started on thyroxine since they exhibit features like weight gain, menstrual disturbances or hypercholesterolemia or based on a gradual rise in TSH levels during follow up.
While the decision to start thyroxine in such patients may not be a simple one, an even more difficult task is to decide if and when to stop the thyroid hormone supplementation. Now, based on a reasonably large study we have data to draw some conclusions on this difficult question.
Burgos and colleagues conducted a systematic review and meta-analysis very pertinent to this issue . They tried to answer the question:
What happens when thyroxine is stopped in patients who were receiving thyroid hormone supplementation?
They systematically searched all major databases and identified 17 observational studies that met predefined eligibility criteria. Overall, these studies provided data related to 1105 patients of which 87% were women between the ages of 5 and 81 years.
In all these studies, patients who were on thyroid hormone replacement previously were asked to discontinue the medication. Subsequently, they were followed up for varying periods of time (as short as 10 days to as long as 5 years) and monitored for maintenance of euthyroid status (biochemically in most studies and clinically in a few studies).
The studies also determined the proportion of patients who had to be restarted on thyroxine supplementation based on rising TSH levels or symptoms.
The findings of this meta-analysis are interesting. When the data from all studies were combined, a third (34%) of the patients who discontinued thyroxine remained euthyroid.
Further analysis based on the indication for thyroxine supplementation revealed that those who were started on thyroxine for subclinical hypothyroidism were more likely to remain euthyroid compared to those in whom it was started for overt hypothyroidism.
The authors also looked at 9 studies that investigated the proportion of patients who were restarted on thyroxine after discontinuation. The data from 843 patients showed that about 63% of patients were restarted thyroxine and the most common reason for putting them back on supplementation was subclinical hypothyroidism.
In this case, a sensitivity analysis showed that rates of restarting were more if the initial indication for thyroxine supplementation was overt hypothyroidism.
- This systematic review provides new insights into an old problem. Most patients started on thyroxine for subclinical hypothyroidism or other non-pressing indications tend to take the medication indefinitely.
- While observational studies suggest benefits in treating patients with subclinical hypothyroidism [2,3], randomised controlled studies have found no such advantage [4,5]. It is in this context that the results of this systematic review become important.
- Although many studies included in the review were methodologically moderate to low in quality, the results indicate that it might be possible and safe to discontinue thyroxine in a significant proportion of patients taking supplements for doubtful reasons and subclinical hypothyroidism.
- Even among those who had to be restarted on thyroxine, the most common reason was subclinical hypothyroidism where the evidence for replacement is not robust.
- In short, we now have evidence, albeit of moderate to low quality, to consider discontinuing thyroid hormone replacement in selected patients.
- Physicians must choose patients who may be ideal candidates for such ‘deprescribing’ in outpatient settings.
- Patients who have started thyroxine supplements for indications other than overt hypothyroidism (especially subclinical hypothyroidism) may benefit the most and a detailed discussion for shared decision making to discontinue might be attempted.
- Regular follow up with emphasis on clinical endpoints and overt hypothyroidism as triggers to restart supplementation seems to be a feasible strategy based on limited yet promising evidence that we now have.
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Disclaimer- The views and opinions expressed in this article are those of the author's and do not necessarily reflect the official policy or position of M3 India.
The author, Dr Aneesh Basheer is an Academician Professor of Medicine from Kerala. He is an expert reviewer of international peer-reviewed medical journals and case reports.
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