Evaluation of adequacy of levo-thyroxine dosage in patients with differentiated thyroid carcinoma: correlation between morning and afternoon TSH determination

L. Conte, E. Monti, S. Gay, P. Marroni, A. Adorno, M. Mittica, M. Mussap, M. Giusti

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: The aim of this study was to judge the reliability of evaluating thyroid-stimulating hormone (TSH) and free thyroxine (f-T4) in the morning and afternoon in differentiated thyroid carcinoma (DTC) patients. Methods: We evaluated 153 DTC patients, aged 61 ± 13 years, in active follow-up in our center after primary treatments and under stabilized levo-thyroxine (L-T4) posology. In each patient, morning and afternoon examinations were performed 1-3 months apart. Blood samples were collected at 08:00–09:00 h and 15:00–16:00 h. TSH and f-T4 were evaluated in both samples. Thyroglobulin (Tg), Tg-antibodies and neck ultrasonography were also evaluated. Results: According to clinical and laboratory examinations, 92% of patients were disease-free, 6% had biochemical disease, and 2% structural disease. L-T4 dosages (1.64 ± 0.38 µg/kg b.w.) proved the same on both occasions, despite slight changes in body weight or L-T4 posology in 15% of patients. Free-T4 values were significantly higher in the afternoon (21.5 ± 0.3 pmol/L) than in the morning (18.8 ± 0.4 pmol/L; P < 0.0001), whereas TSH values were statistically unchanged (morning 0.85 ± 0.25 mIU/L; afternoon 0.72 ± 0.20 mIU/L). There was a significant correlation (P < 0.0001) between the two TSH determinations in the same patients. Conclusions: In DTC patients, follow-up examination consists of clinical and laboratory evaluations. The majority of patients have good disease control. Our study suggests that the adequacy of L-T4 therapy can be monitored equally well either in the morning or in the afternoon. Afternoon examinations can alleviate crowding in hospital ambulatories in the morning.

Original languageEnglish
Pages (from-to)1193-1197
Number of pages5
JournalJournal of Endocrinological Investigation
Volume41
Issue number10
DOIs
Publication statusPublished - Oct 1 2018

Keywords

  • Differentiated thyroid cancer
  • Evening sample
  • L-T4 posology
  • Morning sample
  • TSH

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Endocrinology

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