Balancing Benefits and Risks: Evidence From a Large Community-Based Study

JAMA Intern Med 2013 Oct 07;[EPub Ahead of Print], PN Taylor, A Iqbal, C Minassian, A Sayers, MS Draman, R Greenwood, W Hamilton, O Okosieme, V Panicker, SL Thomas, C Dayan

Commentary By
Peter Lin, MD, CCFP

Are We Over-Treating Our Thyroid Patients?

Thyroid prescriptions increased from 49 million to 70 million in the US between 2006 and 2010, and there was a similar trend in the UK. Researchers looked at > 52,000 patients on thyroid replacement therapy in a UK database, and found that most of the prescriptions were for individuals with TSH levels between 4 and 10 mIU/L. Almost 20% of patients complained of tiredness, 14% of obesity, and 5.8% of depression prior to their treatment. Patients were not very well monitored after their thyroid replacement. Of the patients who did receive follow-up blood tests, 5.8% had TSH levels < 0.1 mIU/L and 10.2% had levels between 0.1 and 0.5 mIU/L. This type of over-replacement could lead to increased osteoporosis and even atrial fibrillation. Interestingly, women and patients with complaints of tiredness or depression were more likely to receive over-replacement therapy and have suppressed levels of TSH. Thankfully, patients at cardiac risk were less likely to receive over-replacement, likely due to the fear of triggering a cardiac event. Also of interest is that 90% of these patients continued with their thyroid replacement therapy. This high compliance rate means that patients really believe in the treatment. So, we must be careful because, once we start, the patients may stay on the medication, and, if we are not monitoring them, more patients may receive over-replacement therapy. The researchers suggest that we follow the American Thyroid Association guidelines, which state that we should treat when the TSH level is > 10 mIU/L. We should treat people with a TSH between 4.5 and 10 mIU/L only if they have signs/symptoms of hypothyroidism, heart failure, or atherosclerosis or if they have thyroid antibodies. If they do not have any of these four features, treatment is not beneficial; hence, monitoring the TSH would be the best option. Also the TSH level normally rises with age, and no treatment is necessary for our elderly patients unless they have the aforementioned features.

Pregnant women and those thinking of conceiving are the main exceptions. The fetus cannot make thyroid hormone and relies solely on the mother. In the first trimester, treat if the TSH is > 2.5 mIU/L because this has been shown to reduce miscarriages and fetal abnormalities. In the second trimester, treat if the TSH is > 3.0 mIU/L, and, in the third trimester, treat if the TSH is > 3.5 mIU/L. If the patient is planning to conceive, then treat if the TSH is > 2.5 mIU/L.

All treated patients must be monitored to avoid over-replacement; their TSH should not be < 0.5 mIU/L. Finally, remember that many factors can cause tiredness and obesity; just because the TSH is between 4.5 and 10 mIU/L does not mean the patient is hypothyroid. In fact, if we just blame tiredness and obesity on the thyroid, we might actually miss the real cause of our patients’ complaints.

Full Story:  http://www.practiceupdate.com/journalscan/6413