Predicting thyroxine requirements following total thyroidectomy

Dipan Mistry, Stephen Atkin, Helen Atkinson, Sinnappa Gunasekaran, Deborah Sylvester, Alan S. Rigby, R. James England

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

Objective Optimal thyroxine replacement following total thyroidectomy is critical to avoid symptoms of hypothyroidism. The aim of this study was to determine the best formula to determine the initiated replacement dose of levothyroxine immediately following total thyroidectomy. Design Prospective study. All patients were initiated on 100 μg levothyroxine and titrated to within the reference range for TSH and free T4. Correlations to height, weight, age, lean body mass (LBM), body surface area (BSA) and body mass index (BMI) were calculated. Patients One hundred consecutive adult patients underwent total thyroidectomy for non-malignant disease. Measurements Comparison between three methods of levothyroxine dose prediction, aiming for a levothyroxine dose correct to within 25 μg of actual dose required. Results Correlations were seen between levothyroxine dose and patient age (r = -0·346, P < 0·01), bodyweight (r = 0·296, P < 0·01), LBM (r = 0·312, P < 0·01), BSA (r = 0·319, P < 0·01) and BMI (r = 0·172, P < 0·05). A regression equation was calculated (predicted levothyroxine dose = [0·943 Ã - bodyweight] + [-1·165 Ã - age] + 125·8), simplified to (levothyroxine dose = bodyweight - age + 125) pragmatically. Initiating patients empirically on 100 μg post-operatively showed that 40% of patients achieved target within 25 μg of their required dose; this increased to 59% when using a weight-only dose calculation (1·6 μg/kg) and to 72% using the simplified regression equation. Conclusions A simple calculated regression equation gives a more accurate prediction of initiated levothyroxine dose following total thyroidectomy, reducing the need for outpatient attendance for dose titration.

Original languageEnglish
Pages (from-to)384-387
Number of pages4
JournalClinical Endocrinology
Volume74
Issue number3
DOIs
Publication statusPublished - Mar 2011
Externally publishedYes

Fingerprint

Thyroidectomy
Thyroxine
Body Surface Area
Body Mass Index
Weights and Measures
Hypothyroidism
Reference Values
Outpatients
Prospective Studies

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism

Cite this

Mistry, D., Atkin, S., Atkinson, H., Gunasekaran, S., Sylvester, D., Rigby, A. S., & England, R. J. (2011). Predicting thyroxine requirements following total thyroidectomy. Clinical Endocrinology, 74(3), 384-387. https://doi.org/10.1111/j.1365-2265.2010.03940.x

Predicting thyroxine requirements following total thyroidectomy. / Mistry, Dipan; Atkin, Stephen; Atkinson, Helen; Gunasekaran, Sinnappa; Sylvester, Deborah; Rigby, Alan S.; England, R. James.

In: Clinical Endocrinology, Vol. 74, No. 3, 03.2011, p. 384-387.

Research output: Contribution to journalArticle

Mistry, D, Atkin, S, Atkinson, H, Gunasekaran, S, Sylvester, D, Rigby, AS & England, RJ 2011, 'Predicting thyroxine requirements following total thyroidectomy', Clinical Endocrinology, vol. 74, no. 3, pp. 384-387. https://doi.org/10.1111/j.1365-2265.2010.03940.x
Mistry, Dipan ; Atkin, Stephen ; Atkinson, Helen ; Gunasekaran, Sinnappa ; Sylvester, Deborah ; Rigby, Alan S. ; England, R. James. / Predicting thyroxine requirements following total thyroidectomy. In: Clinical Endocrinology. 2011 ; Vol. 74, No. 3. pp. 384-387.
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AB - Objective Optimal thyroxine replacement following total thyroidectomy is critical to avoid symptoms of hypothyroidism. The aim of this study was to determine the best formula to determine the initiated replacement dose of levothyroxine immediately following total thyroidectomy. Design Prospective study. All patients were initiated on 100 μg levothyroxine and titrated to within the reference range for TSH and free T4. Correlations to height, weight, age, lean body mass (LBM), body surface area (BSA) and body mass index (BMI) were calculated. Patients One hundred consecutive adult patients underwent total thyroidectomy for non-malignant disease. Measurements Comparison between three methods of levothyroxine dose prediction, aiming for a levothyroxine dose correct to within 25 μg of actual dose required. Results Correlations were seen between levothyroxine dose and patient age (r = -0·346, P < 0·01), bodyweight (r = 0·296, P < 0·01), LBM (r = 0·312, P < 0·01), BSA (r = 0·319, P < 0·01) and BMI (r = 0·172, P < 0·05). A regression equation was calculated (predicted levothyroxine dose = [0·943 Ã - bodyweight] + [-1·165 Ã - age] + 125·8), simplified to (levothyroxine dose = bodyweight - age + 125) pragmatically. Initiating patients empirically on 100 μg post-operatively showed that 40% of patients achieved target within 25 μg of their required dose; this increased to 59% when using a weight-only dose calculation (1·6 μg/kg) and to 72% using the simplified regression equation. Conclusions A simple calculated regression equation gives a more accurate prediction of initiated levothyroxine dose following total thyroidectomy, reducing the need for outpatient attendance for dose titration.

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