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Cited by 63Thyroid Disorders and TreatmentsThyroid and Parathyroid SurgeryThyroid Cancer Diagnosis and Treatment

Changes in Prescription Routines for Treating Hypothyroidism Between 2001 and 2015: An Observational Study of 929,684 Primary Care Patients in Copenhagen

Medici, Bjarke Borregaard, Nygaard, Birte, la Cour, Jeppe Lerche, Grand, Mia Klinten, Siersma, Volkert, Nicolaisdottir, Dagny Ros, Lind, Bent, Olivarius, Niels de Fine +1 more·2019·Thyroid®
DOI 10.1089/thy.2018.0539
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Abstract

Background: Increased public attention toward health and quality-of-life issues has led to more intensified screening for various medical conditions, including hypothyroidism. A falling serum thyrotropin (s-TSH) at initiation of levothyroxine (LT4) treatment has been reported in the United Kingdom between 2001 and 2009, indicating a falling TSH threshold, which may lead to less benefit from therapy and possibly overtreatment. The aim of this study was to investigate changes in s-TSH threshold used by general practitioners to initiate LT4 therapy between 2001 and 2015 in Copenhagen. Methods: Retrospective analysis was conducted of all s-TSH measurements between 2001 and 2015 performed at the general practitioners' joint laboratory merged with The Danish Register of Medicinal Products Statistics and The Danish National Patient Registry. For each year, both the median s-TSH at therapy initiation and the estimated treatment threshold were calculated from all s-TSH measurements performed in that year, representing the s-TSH level where the estimated probability of starting LT4 therapy was 50%. Results: A total of 929,684 individuals with 2,975,277 s-TSH measurements were included in the calculations. The size and composition of the study population remained virtually unchanged. During the study period, the number of performed s-TSH measurements increased from 110,886 to 292,911 (164%), and the number of patients initiating LT4 therapy increased from 786 to 1825 (132%), though this was comparably unchanged from 2010 to 2015. The median s-TSH at therapy initiation decreased from 10 mIU/L (interquartile range 5.2–29.7 mIU/L) in 2001 to 6.8 mIU/L (interquartile range 5.1–11 mIU/L) in 2015, while the estimated treatment threshold decreased from 28.3 mIU/L [confidence interval 21.0–40.2 mIU/L] in 2001 to 14.2 mIU/L [confidence interval 12.0–18.0 mIU/L] in 2007. In 2015, 25% of patients started LT4 therapy with s-TSH ≤5 mIU/L, and during the entire period, 50% of patients started therapy with a single s-TSH measurement >5 mIU/L. Conclusions: This study performed on a sizeable primary care population demonstrates a considerable fall in the threshold for initiating LT4 therapy in hypothyroid patients. This increases the risk of futile treatment as well as overtreatment.

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  • The prevalence of treated hypothyroidism has increased in the last decades, mostly due to an increase in the prevalence of treated subclinical hypothyroidism.

    “We have seen an increase in the prevalence of treated hypothyroidism in the last decades, mostly due to an increase in the prevalence of treated subclinical hypothyroidism [27,28].”

    From T4+T3 Combination Therapy: An Unsolved Problem of Increasing Magnitude and Complexity (2021) · cites this paper as [28]

  • Most patients treated with LT4 in the last two decades had subclinical hypothyroidism (median TSH before treatment 6.8 to 7.9 mU/L).

    “Epidemiological data (summarized above) demonstrate most patients treated with LT4 in the last two decades had subclinical hypothyroidism (their median TSH before treatment was 6.8 to 7.9 mU/L).”

    From T4+T3 Combination Therapy: An Unsolved Problem of Increasing Magnitude and Complexity (2021) · cites this paper as [28]

  • There is growing evidence that the TSH level when levothyroxine is initiated is steadily falling, with a median TSH value at levothyroxine prescription of around 7.0 mIU/L.

    “However, there is growing evidence that the TSH level when levothyroxine is initiated is steadily falling, 7,111 with a median TSH value at levothyroxine prescription of around 7•0 mIU/L.”

    From Hypothyroidism (2024) · cites this paper as [111]

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Authors
Medici, B. B., Nygaard, B., la Cour, J. L., Grand, M. K., Siersma, V., Nicolaisdottir, D. R., Lind, B., Olivarius, N. D. F., & Andersen, C. L.
Affiliations
  • Herlev Hospital (DK)
  • Center for Endocrinology and Metabolism, Department Internal Medicine, Herlev and Gentofte Hospitals, Herlev, Denmark.
  • University of Copenhagen (DK)
  • The Research Unit for General Practice and Section of General Practice, Department of Public Health, University of Copenhagen, Copenhagen, Denmark.
Corresponding author
Medici, Bjarke Borregaard
ORCID
Venue
Thyroid®
Publisher
SAGE Publications
Published
2019-07
Volume
29
Issue
7
Pages
910-919
ISSN
  • 1050-7256 (ISSN-L)
  • 1557-9077
DOI
10.1089/thy.2018.0539
OpenAlex
W2941830626
Cited by
63
References
32
Citations by year
2026: 5 · 2025: 4 · 2024: 13 · 2023: 6 · 2022: 8 · 2021: 11 · 2020: 7 · 2019: 8 · 2013: 1
FWCI
6.90
Type
journal article
Language
en
Open access
closed
Licence
journals.sagepub.com/page/policies/text-and-data-mining-license (tdm)
Locations
  • Thyroid (publishedVersion)
  • PubMed (publishedVersion)
  • Research at the University of Copenhagen (University of Copenhagen) (submittedVersion)
Topics
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Thyroid Disorders and Treatments
  • Health Sciences › Medicine › Surgery › Thyroid and Parathyroid Surgery
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Thyroid Cancer Diagnosis and Treatment
Keywords
hypothyroidism, levothyroxine, overtreatment, primary care prescribing, treatment initiation, general practitioners, Copenhagen, Denmark, quality of life, health care costs
MeSH terms
Adult, Aged, Denmark, Female, Humans, Hypothyroidism, Male, Middle Aged, Practice Patterns, Physicians', Primary Health Care, Thyrotropin, Thyroxine

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