Levothyroxine replacement dosage determination after thyroidectomy

Jin, Judy; Allemang, Matthew T.; McHenry, Christopher R.

doi:10.1016/j.amjsurg.2012.10.015

Cited by 46 publications

(33 citation statements)

References 7 publications

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“…L-T 4 dose requirements have been well studied and various regimes based on weight, BMI or more refined algorithms have been proposed to put patients on a presumed adequate dose from the very beginning (10,11,12,13,14,15,16,35,36,37,38,39). As useful as these algorithms may be for average predictions and initial guidance in the general population, they do not take into account individual variations in the response to L-T 4 , such as conversion efficiency.…”

Section: Discussionmentioning

confidence: 99%

“…This parameter has evolved into the main treatment target to be monitored and kept within an assumed euthyroid range (9). A number of studies have attempted to predict T 4 requirement, and various regimes for a starting dose have been proposed based on an average of 1.6 mg/kg body weight (BW) or by more refined weight-or BMI-related algorithms (10,11,12,13,14,15,16).…”

Section: Introductionmentioning

confidence: 99%

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Variation in the biochemical response to l-thyroxine therapy and relationship with peripheral thyroid hormone conversion efficiency

Midgley¹,

Larisch²,

Dietrich³

et al. 2015

Endocrine Connections

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Several influences modulate biochemical responses to a weight-adjusted levothyroxine (L-T 4 ) replacement dose. We conducted a secondary analysis of the relationship of L-T 4 dose to TSH and free T 3 (FT 3 ), using a prospective observational study examining the interacting equilibria between thyroid parameters. We studied 353 patients on steady-state L-T 4 replacement for autoimmune thyroiditis or after surgery for malignant or benign thyroid disease. Peripheral deiodinase activity was calculated as a measure of T 4 -T 3 conversion efficiency. In euthyroid subjects, the median L-T 4 dose was 1.3 mg/kg per day (interquartile range (IQR) 0.94,1.60). The dose was independently associated with gender, age, aetiology and deiodinase activity (all P!0.001). Comparable FT 3 levels required higher L-T 4 doses in the carcinoma group (nZ143), even after adjusting for different TSH levels. Euthyroid athyreotic thyroid carcinoma patients (nZ50) received 1.57 mg/kg per day L-T 4 (IQR 1.40, 1.69), compared to 1.19 mg/kg per day (0.85,1.47) in autoimmune thyroiditis (P!0.01, nZ76) and 1.08 mg/kg per day (0.82, 1.44) in patients operated on for benign disease (P! 0.01, nZ80). Stratifying patients by deiodinase activity categories of !23, 23-29 and O29 nmol/s revealed an increasing FT 3 -FT 4 dissociation; the poorest converters showed the lowest FT 3 levels in spite of the highest dose and circulating FT 4 (P!0.001). An L-T 4 -related FT 3 -TSH disjoint was also apparent; some patients with fully suppressed TSH failed to raise FT 3 above the median level. These findings imply that thyroid hormone conversion efficiency is an important modulator of the biochemical response to L-T 4 ; FT 3 measurement may be an additional treatment target; and L-T 4 dose escalation may have limited success to raise FT 3 appropriately in some cases.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Variation in the biochemical response to l-thyroxine therapy and relationship with peripheral thyroid hormone conversion efficiency

Midgley¹,

Larisch²,

Dietrich³

et al. 2015

Endocrine Connections

View full text Add to dashboard Cite

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“…On the other hand, a LT4 dose that is to high may cause temporary hypothyroidism with symptoms like arrhythmias, which would be highly problematic in older adults [19]. A great deal of research in the literature has presented discussions regarding the limitations of weight-based LT4 dosing following a total thyroidectomy; however, the importance of BMI, gender, and age when forming a dosing strategy is still very controversial [9,11,12]. It is important to know a patient's physiological LT4 requirements when calculating the amount of LT4 required for the prevention of hypothyroidism following a total thyroidectomy.…”

Section: Discussionmentioning

confidence: 99%

“…Factors such as the patient's BW, pregnancy status, menopausal state, age, lean body mass (LBM) and BSA, as well as any drugs being taken and for what diseases all affect this calculation [6,[20][21][22]. Jin et al showed that the dose of T4 was directly related to the BW and suggested a weight-based treatment [12]. A study performed by Di Donna et al confirmed that older patients required less weight-based dosing.…”

Section: Discussionmentioning

confidence: 99%

“…Commonly, the initial dose of LT4 replacement is weight-based, recommended at a range of 1.6-1.7 µg/kg/day, with some reports of up to 2.1 µg /kg [2][3][4][5][6]. Some researchers have suggested a relationship between the replacement LT4 requirement and things like body mass index (BMI) or body surface area (BSA) [7,8], sex and menopause [9][10][11][12], age [11][12][13], and the disease resulting in hypothyroidism [3]. There is not much literature regarding surgically-induced hypothyroidism and thyroid hormone replacement, and the reports there are, lack a lone predictive factor with a strong relationship to accurately find a dosage of LT4 after surgery.…”

Section: Introductionmentioning

confidence: 99%

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How to calculate levothyroxine dosage after total thyroidectomy

Soylu¹

2018

Ann Clin Anal Med

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Aim: To prevent hypothyroidism or hyperthyroidism, it is critical to administer thyroxine replacement after a total thyroidectomy. Herein, the best formula for determining the initiating replacement dose of levothyroxine (LT4) after a total thyroidectomy was determined. Material and Method: In this retrospective study, all of the patients were initiated on 100 µg LT4 and titrated to within the reference range for thyroid function test (TFT) and free T4. Correlations to body weight (BW), ideal BW (IBW), body surface area (BSA), and body mass index (BMI) were calculated. A total of 67 adult patients underwent a total thyroidectomy for benign thyroid disease. Comparisons of the 5 different formulas in the literature and classical methods were made in calculating the LT4 dose estimation. Results: Correlations were seen between the LT4 dose and patient BW (r=0.445 P<0.005), IBW (r=0.438 P<0.005), BSA (r=0.472, P<0.005), and BMI (r=0.275, P<0.005). Comparisons of the 5 different formulas and the classical methods in the literature were made in calculating the LT4 dose estimation. We found that all of the formulas were statistically close to each other when the LT4 dose formulas described in the literature were compared. A regression equation was calculated (predicted LT4 dose=21.3+(0.46xBW)+(0.77xIBW) pragmatically. Discussion: Although the correct initial dosing of LT4 is still difficult, the formula we developed may increase the number of euthyroid patients over a shorter period of time postoperatively. The LT4 requirements of just the conventional formula (1.6 µg/kg), based on BW, were not statistically different, making it practical to use the weight-based calculation of the LT4 dose as a reasonable option using BW.

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Surgical Procedures. Thyroidectomy: Indications, Flexible Laryngoscopy, Operative Techniques, Recurrent Laryngeal Nerve Monitoring, and Management of Complications

Bobanga

McHenry

2021

Endocrine Surgery Comprehensive Board Exam Guide

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Levothyroxine replacement dosage determination after thyroidectomy

Cited by 46 publications

References 7 publications

Variation in the biochemical response to l-thyroxine therapy and relationship with peripheral thyroid hormone conversion efficiency

Variation in the biochemical response to l-thyroxine therapy and relationship with peripheral thyroid hormone conversion efficiency

How to calculate levothyroxine dosage after total thyroidectomy

Surgical Procedures. Thyroidectomy: Indications, Flexible Laryngoscopy, Operative Techniques, Recurrent Laryngeal Nerve Monitoring, and Management of Complications

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