MedicalResearch.com Interview with:
Antonio C. Bianco, MD, PhD
Rush University Medical Center
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: The standard of care for patients with hypothyroidism is treatment with levothyroxine. The dosage of levothyroxine is adjusted for each patient with the goal of normalizing blood levels of TSH. About 15% of the patients treated this way exhibit variable degrees of residual symptoms, despite having a normal TSH level. These symptoms include difficulty losing weight, low energy and depression. However, given the subjective nature of these complains and that the blood levels of TSH are normal, many times such symptoms are dismissed by physicians as non-thyroid related.
The present study utilized NHANS data to ask whether individuals on levothyroxine differ in 52 subjective and objective parameters when compared with matched control individuals. Out of the approximately 10,000 participants, 469 were on levothyroxine. When compared with a group of 469 matched controls, the individuals on levothyroxine
(i) weighed about 10 pounds more despite ingesting slightly less calories per day,
(ii) were 1.6-fold more likely to be on a beta-blocker,
(iii) were 1.5-fold more likely to be on statin,
(iv) were 1.46-fold more likely to be on antidepressant,
(v) were 30% overall less physically active: specifically, these patients reported 34% less work-related physical activity and 42% less walking or biking.
MedicalResearch.com: What should readers take away from your report?
Response: Of course these findings need to be tested in other populations. However, at face value the present study indicates that the normalization of TSH levels in hypothyroid patients might not be as useful as once thought to monitor treatment. Despite normal TSH levels, patients are at a significant higher risk of developing depression and a metabolic dysfunction characterized by increased body weight and high cholesterol levels.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Response: Repeat the study in other populations. Expand the study to individuals that are being followed with alternative treatments for hypothyroidism; for example, individuals that are taking combination therapy with levothyroxine and liothyronine. Investigate whether genetics play a role on how patients respond to levothyroxine therapy.
MedicalResearch.com: Is there anything else you would like to add?
Response: Physicians should discuss these results with their patients and explain the limitations of the levothyroxine therapy. We have been saying that by normalizing blood levels of TSH all symptoms associated with hypothyroidism should go away. This probably needs to change. Having this discussion is particularly important with patients that are considering treatment that involves surgical removal of the thyroid gland.
MedicalResearch.com: Thank you for your contribution to the MedicalResearch.com community.
Sarah J. Peterson, Elizabeth A. McAninch, Antonio C. Bianco.Is a Normal TSH Synonymous with “Euthyroidism” in Levothyroxine Monotherapy? The Journal of Clinical Endocrinology & Metabolism, 2016; jc.2016-2660 DOI:10.1210/jc.2016-2660
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