This article is more than 5 years old. Information may no longer be current.
Weight-focused calculation methods for levothyroxine doses effective for patients
NASHVILLE, Tenn. — Calculating levothyroxine dose by weight is comparable to using body-fat percentages or BMI, according to data presented here.
“Traditionally, starting replacement doses of levothyroxine have been calculated by multiplying the patient’s total body weight by 1.6 ug/kg,” the researchers wrote. “However, this simple calculation does not take into account several factors like obesity, gender, sex, age, body fat percentage, hormonal state, interfering medications or supplements and other comorbidities.”
Malek Cheikh, MD, of Medstar Union Hospital in Baltimore, and colleagues evaluated survey data from 51 adults with hypothyroidism (mean age, 61; 87% women) to determine if the standard calculation for deciding levothyroxine dose needs revision. There was a 44% estimated compliance with therapy.
Through bivariate analysis, adherence to medication was the only factor that showed a meaningful relationship to normal thyroid state. No significant differences were found in the levothyroxine dose that was effective to control thyroid levels between the traditional weight-based thyroid dose, or those calculated using body-fat percentage or BMI.
“So far our data indicate that the only variable significantly affecting the dose is the adherence to medication,” the researchers wrote. “However, we are in the process of analyzing retrospective data collected from euthyroid patients on thyroid hormone replacement who underwent thyroidectomy to further clarify the ideal relationship between weight and thyroid dose.” – by Amber Cox
Reference:
Cheikh M, et al. Abstract #1104. Presented at: AACE 24th Annual Scientific & Clinical Congress; May 13-17, 2015; Nashville, Tenn.
Disclosure: The researchers report no relevant financial disclosures.