Thyroid Replacement Therapy may Predispose to More Comorbidities

 In Naturopathic News

Node Smith, ND

Two papers presented at the 100th annual meeting of the Endocrine Society question the benignity of replacement thyroid therapy, especially in subclinical cases.1 One study looked at the increase in comorbidities and lower quality of life in individuals on replacement hormone therapy versus those who don’t take the hormone. The other study looked at an increase in mortality in individuals over the age of 65 on newly prescribed thyroid hormone.

Hypothyroidism + Levothyroxine

Hypothyroidism is an extremely common disorder of the endocrine system, and it is typically treated with replacement hormone levothyroxine (LT4). Something to consider, however, lead author Hanneke Wouters, an M.D./Ph.D student at the University of Groningen reminds us is that “about 10 percent of patients on thyroid hormone continue to experience symptoms and disturbed well-being, despite the fact that their blood thyroid hormone levels are within the normal range.”

More Comorbidities

The first study showed that individuals treated with LT4 had a lower quality of life when compared to matched individuals not on thyroid hormone. This group also experienced more comorbidity.

34,440 individuals were studied

The study looked at records from 34,440 individuals involved in the Dutch Lifelines cohort study. Medical history, thyroid hormone concentration, medication, and quality of life were all assessed.

Those taking LT4 had 80 percent comorbidity compared with 60 percent of those without it

Of 955 individuals taking LT4, over 80 percent had comorbidity, compared with only 60 percent of matched participants not taking LT4. Overall, only 60 percent of those taking LT4 had normal TSH levels, while 89 percent of those not taking the drug had TSH levels within a normal range. Individuals on LT4 scored lower in almost all quality of life areas.

Levothyroxine and increased Mortality

Also presented at ENDO 2018, a study showed that patients 65 years or above who were given LT4 for subclinical hypothyroidism had a significantly increased mortality rate. Subclinical hypothyroid was assessed as a TSH under 10 mIU/L.


  1. Wolffenbuttel BHR, Wouters HJCM, Slagter SN, et al. Thyroid function and metabolic syndrome in the population-based LifeLines cohort study. BMC Endocr Disord. 2017;17(1):65.
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Node Smith, ND, is a naturopathic physician in Portland, OR and associate editor for NDNR. He has been instrumental in maintaining a firm connection to the philosophy and heritage of naturopathic medicine among the next generation of docs. He helped found the first multi-generational experiential retreat, which brings elders, alumni, and students together for a weekend camp-out where naturopathic medicine and medical philosophy are experienced in nature. Four years ago he helped found the non-profit, Association for Naturopathic ReVitalization (ANR), for which he serves as the board chairman. ANR has a mission to inspire health practitioners to embody the naturopathic principles through experiential education. Node also has a firm belief that the next era of naturopathic medicine will see a resurgence of in-patient facilities which use fasting, earthing, hydrotherapy and homeopathy to bring people back from chronic diseases of modern living; he is involved in numerous conversations and projects to bring about this vision.

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