Age and the Daily Dose of Thyroxine Replacement Therapy for Hypothyroidism

Young, R. E.; Jones, S J; Bewsher, P. D.; Hedley, A. J.

doi:10.1093/ageing/13.5.299

Cited by 7 publications

(3 citation statements)

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“…Several studies have suggested that advancing age leads to a decreased LT 4 dose requirement (9,(25)(26)(27)(28), but most of these studies did not include IBW and gender in their analyses. Only three studies included gender (25,26,28) and these studies either documented the age-related decline in LT 4 dose in men only (26), showed the effect in only men and menopausal women (25), or were unable to separate the effects of age and gender (28).…”

Section: Discussionmentioning

confidence: 99%

“…Treatment of patients with hypothyroidism due to Hashimoto's thyroiditis or radioiodine ablation of Graves' disease requires lesser doses of LT 4 than treatment of patients who have a complete absence of thyroid tissue (4,6). Other factors implicated in modifying LT 4 dose requirement include medications altering thyroxine binding or metabolism (23,24) and patient age, with dose requirements decreasing with increasing age (9,(25)(26)(27).…”

Section: Introductionmentioning

confidence: 99%

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Levothyroxine Replacement Doses Are Affected by Gender and Weight, But Not Age

Devdhar

Drooger

Pehlivanova

et al. 2011

Thyroid

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Background: Body weight (BW) and age have been shown to affect the dose of levothyroxine (LT 4 ) that results in normalization of serum thyroid-stimulating hormone (TSH) in hypothyroid patients. Our objective was to determine whether gender, menstrual status, and ideal BW (IBW) also affect the LT 4 dose required to achieve a serum TSH within the normal range. Methods: We retrospectively reviewed the charts of patients being treated for primary hypothyroidism who had TSH values within a normal range. We selected patients aged 18-85 years who were taking LT 4 without any confounding medications, and who had no serious chronic conditions. Their LT 4 doses, referred to here as LT 4 dose requirements, based on both BW and IBW were documented. The relationship between gender, menstrual status, age, serum TSH concentrations, and the degree of overweight on LT 4 dose requirements were determined using multivariate analyses. Results: Women were significantly more overweight than men (ratio of BW/IBW was 1.35 for women vs. 1.17 for men, p < 0.0001). LT 4 requirements based on BW did not differ by gender when age was included in the model. However, when degree of overweight was also included, men required lower LT 4 doses than both premenopausal women (1.34 mg/kg vs. 1.51 mg/kg, p ¼ 0.038) and menopausal women (1.34 mg/kg vs. 1.49 mg/ kg, p ¼ 0.023). When examining IBW using a model incorporating age, men also required lower LT 4 doses than both premenopausal women (1.64 mg/kg vs. 1.92 mg/kg, p ¼ 0.0033) and menopausal women (1.64 mg/kg vs. 1.90 mg/kg, p ¼ 0.0024). Serum TSH concentrations were not significantly different in any of the gender groups. There was no relationship between serum TSH and either age or BW. The initial serum TSH concentration was by design with the normal range, but the concentration within that range was not a significant predictor of the LT 4 replacement dose in any of the models. Conclusion: In contrast to previous studies suggesting that age affects LT 4 replacement requirements, we found that age-based differences in doses are secondary to differences in BW and gender. In addition, in contrast to prior studies showing that lean body mass, but not gender, affected LT 4 dose, we instead found a significant impact of gender. Gender-based differences in dose requirement only became apparent either when IBW was used to correct for the dose or when degree of overweight was included in the model. Gender differences in LT 4 dose requirement exist, but are masked unless gender-based differences in degree of overweight are also considered.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Levothyroxine Replacement Doses Are Affected by Gender and Weight, But Not Age

Devdhar

Drooger

Pehlivanova

et al. 2011

Thyroid

View full text Add to dashboard Cite

show abstract

“…Although this seems to be an easy goal, previous studies have shown that approximately 20% of individuals with hypothyroidism, including those with low-risk thyroid cancer, are over-treated, and almost the same percentage are under-treated (5)(6)(7)(8)(9)(10)(11)(12). Despite the generally held belief that iatrogenic thyroid disease may pose more of a risk for patients in older age groups (1,13), older patients seem to be at similar, or even greater risk, of being treated with larger doses of LT4 (14), or of not being treated to an appropriate thyrotropin (TSH) goal (5,7). There is also evidence that LT4 may be prescribed more frequently in the elderly (5,7), and that there is a trend over time to initiate LT4 treatment with lesser degrees of TSH elevation in patients of all age groups (11,15).…”

Section: Introductionmentioning

confidence: 99%