American Thyroid Association

American Thyroid Association

September 23, 2016
1 min read

Patients with Hashimoto's thyroiditis require similar T4 levels regardless of body weight

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DENVER — Thyroxine requirements in Hashimoto’s thyroiditis are similar for patients with normal weight or overweight, study data show.

“The analysis of thyroxine requirement in a population of adult hypothyroid patients with Hashimoto’s thyroiditis revealed that the dose needed by overweight patients is similar to that in normal-weight patients,” Camilla Virili, MD, of the department of medicosurgical sciences and biotechnologies at Sapienza, University of Rome in Italy, told Endocrine Today. “On the contrary, obese hypothyroid patients require progressively lower thyroxine dose as BMI increases.”

Virili and colleagues evaluated 95 adults with Hashimoto’s thyroiditis to compare thyroxine requirements in patients with normal weight, overweight or obesity taking thyroxine in a tightly controlled fashion.

Participants with Hashimoto’s thyroiditis were categorized according to BMI: overweight (n = 26), class I obesity (n = 17), class II obesity (n = 10) and class III obesity (n = 7); 35 age-matched controls with normal BMI were also included.

All participants were treated with oral T4 under fasting conditions and were instructed not to eat or drink for at least 1 hour after treatment. Daily T4 level was assessed in each subgroup after the desired serum thyroid-stimulating hormone level (0.8-2.5 mIU/L) was reached.

Higher median T4 requirements were found in controls compared with the other groups (P < .0001). However, participants with normal weight or overweight required similar T4 doses to obtain similar TSH values. Participants with obesity required less T4 compared with participants with overweight or normal weight (P < .0001). T4 requirement was inversely related to BMI, ranging from 1.2 lg/kg per day to 1 lg/kg per day (P = .023).

“This study has been performed following a tightly controlled schedule of treatment and strict exclusion criteria leading to a significantly lower T4 requirement than those described until now,” Virili said. “This precise tailoring of T4 dose enables endocrinologists to avoid under- and overtreatment, namely in obese patients. The individual tailoring of T4 dose is key for any possible estimate of the thyroxine dose to be prescribed and should be a prerequisite for any study on thyroid hormone treatment.” – by Amber Cox


Virili C, et al. Poster 48. Presented at: 86th Annual Meeting of the American Thyroid Association; Sept. 21-25, Denver.

Disclosure: Virili reports no relevant financial disclosures.