A New Strategy to Estimate Levothyroxine Requirement After Total Thyroidectomy for Benign Thyroid Disease

Donna, Vincenzo Di; Santoro, M Giannotti; Waure, Chiara de; Ricciato, Maria Pia; Paragliola, Rosa Maria; Pontecorvi, Alfredo; Corsello, Salvatore Maria

doi:10.1089/thy.2014.0111

Cited by 40 publications

(39 citation statements)

References 31 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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“…Hence, few methods in the literature have described an optimal calculation for the starting dose of LT4 following thyroidectomy. These are based on BMI, BW, age and sex [7,[13][14][15][16] (Table 1). The purpose of this study was to compare the various methods of T4 replacement described in the literature. )…”

Section: Introductionmentioning

confidence: 99%

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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“…Several studies dealing with T 4 requirement have been carried out on patients with primary hypothyroidism, with or without thyroid in situ (see (6,9) for a review). Some of these studies focused on factors affecting the therapeutic dose, such as body weight (6,12), BMI (13), amount of residual thyroid tissue, patients' age and drugs (14,15,16), and only a fraction of them examined T 4 requirement after total thyroidectomy (7,8,9,10,11). However, most of these latter reports were retrospective and/or compared results obtained in different groups of patients (15,16,17), and/or in heterogeneous therapeutic settings (7,16).…”

Section: Introductionmentioning

confidence: 99%

Individually-tailored thyroxine requirement in the same patients before and after thyroidectomy: a longitudinal study

Duca

Santaguida

Brusca

et al. 2015

European Journal of Endocrinology

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Objective: Thyroxine (T 4 ) requirement after total thyroidectomy for differentiated thyroid carcinoma (DTC) is a debated issue. As most of the studies in the area have been retrospective and/or performed with heterogeneous therapeutic approaches, we designed our study to determine T 4 requirement in the same patients and treatment settings, before and after total thyroidectomy. Design, patients and methods: This was a longitudinal study including 23 goitrous patients treated with T 4 in an individually tailored fashion. All patients exhibited a stable TSH (median TSHZ0.28 mU/l) at a stable T 4 dose for at least 1 year before surgery (median T 4 doseZ1.50 mg/kg per day). The patients underwent total thyroidectomy based on cancer suspicion or compressive symptoms. Eventually diagnosed as having DTC (pT1b-pT2N0) and following surgical and radiometabolic treatment, they were treated with the same pre-surgical doses of T 4 . Results: Three months after surgery,using the same pre-surgical dose, median TSH increased up to 5.38 mU/l (P!0.0001) and so the T 4 dose had to be increased (median T 4 doseZ1.95 mg/kg per day; C30%; P!0.0001). Once divided by patients' age, we observed that, after thyroidectomy and maintaining the same pre-surgical dose, serum TSH significantly increased both in younger and in older patients (median TSHZ4.57 and 6.11 mU/l respectively). Serum TSH was restored to the pre-surgical level by increasing the dose up to 1.95 and 1.77 mg/kg per day (C25 and C21%) respectively. Conclusions: Following the same treatment regimen, a thyroidectomized patient requires one-third higher therapeutic T 4 dose than before surgery. Despite this increase, the dose of T 4 needed in our patients remains significantly lower than that previously described in athyreotic patients.

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A New Strategy to Estimate Levothyroxine Requirement After Total Thyroidectomy for Benign Thyroid Disease

Cited by 40 publications

References 31 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

Individually-tailored thyroxine requirement in the same patients before and after thyroidectomy: a longitudinal study

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