Predicting thyroxine requirements following total thyroidectomy

Mistry, Dipan; Atkin, Stephen L.; Atkinson, Helen; Gunasekaran, S.; Sylvester, Deborah; Rigby, Alan S.; England, Ruth

doi:10.1111/j.1365-2265.2010.03940.x

Cited by 43 publications

(50 citation statements)

References 18 publications

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“…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%

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: 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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“…There is a general consensus that an increased need for T 4 is observed in patients following thyroidectomy (7,15,16,17). However, the quality of evidence in the guidelines prepared by the ATA task force was only moderate (25), because of the differences in the design of the studies, in the characteristics of patients and in the standardization of treatments.…”

Section: Discussionmentioning

confidence: 98%

“…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). At best, some authors used empirical and continuously adjusted T 4 doses and mathematical models to predict the postsurgical dose (16,17). A prospective pre-and post-surgical study on the same patients was carried out by Jonklaas et al (18) who showed similar T 3 levels before and after surgery.…”

Section: Introductionmentioning

confidence: 99%

“…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). At best, some authors used empirical and continuously adjusted T 4 doses and mathematical models to predict the postsurgical dose (16,17).…”

Section: Introductionmentioning

confidence: 99%

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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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“…Previous studies revealed that age was found to affect the dose of levothyroxine needed for normalization of serum TSH. The dose per kg of body weight was found to be inversely related to age [10]. Rosenbaum et al [11] found that elderly patients with hypothyroidism need less daily levothyroxine than younger patients.…”

Section: Discussionmentioning

confidence: 99%

Comparison Among the Daily Levothyroxine Doses According to the Etiology of Hypothyroidism

Lima

2013

J Endocrinol Metab

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Background: The initial doses of levothyroxine (LT4) replacement therapy in patients with hypothyroidism in clinical practice are usually empirical, perhaps because of the lack of data suggesting how much hormone is needed in each patient's situation. The aim of our study is to evaluate the daily dose of oral LT4 needed to achieve the TSH goals in patients with hypothyroidism caused by different etiologies.

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Predicting thyroxine requirements following total thyroidectomy

Cited by 43 publications

References 18 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

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

Comparison Among the Daily Levothyroxine Doses According to the Etiology of Hypothyroidism

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