Cited by 139Thyroid Disorders and TreatmentsThyroid and Parathyroid SurgeryHormonal and reproductive studies

The DOI matches its Crossref record; 52 of the 54 references it cites were found in a registry or an index; none of the 23 sources its claims cite is checked for support yet.

Thyroid replacement therapy, thyroid stimulating hormone concentrations, and long term health outcomes in patients with hypothyroidism: longitudinal study

Open access

Abstract

Objective: To explore whether thyroid stimulating hormone (TSH) concentration in patients with a diagnosis of hypothyroidism is associated with increased all cause mortality and a higher risk of cardiovascular disease and fractures. Design: Retrospective cohort study. Setting: The Health Improvement Network (THIN), a database of electronic patient records from UK primary care. Participants: Adult patients with incident hypothyroidism from 1 January 1995 to 31 December 2017. Exposure: TSH concentration in patients with hypothyroidism. Main outcome measures: Ischaemic heart disease, heart failure, stroke/transient ischaemic attack, atrial fibrillation, any fractures, fragility fractures, and mortality. Longitudinal TSH measurements from diagnosis to outcomes, study end, or loss to follow-up were collected. An extended Cox proportional hazards model with TSH considered as a time varying covariate was fitted for each outcome. Results: 162 369 patients with hypothyroidism and 863 072 TSH measurements were included in the analysis. Compared with the reference TSH category (2-2.5 mIU/L), risk of ischaemic heart disease and heart failure increased at high TSH concentrations (>10 mIU/L) (hazard ratio 1.18 (95% confidence interval 1.02 to 1.38; P=0.03) and 1.42 (1.21 to 1.67; P<0.001), respectively). A protective effect for heart failure was seen at low TSH concentrations (hazard ratio 0.79 (0.64 to 0.99; P=0.04) for TSH <0.1 mIU/L and 0.76 (0.62 to 0.92; P=0.006) for 0.1-0.4 mIU/L). Increased mortality was observed in both the lowest and highest TSH categories (hazard ratio 1.18 (1.08 to 1.28; P<0.001), 1.29 (1.22 to 1.36; P<0.001), and 2.21 (2.07 to 2.36; P<0.001) for TSH <0.1 mIU/L, 4-10 mIU/L, and >10 mIU/L. An increase in the risk of fragility fractures was observed in patients in the highest TSH category (>10 mIU/L) (hazard ratio 1.15 (1.01 to 1.31; P=0.03)). Conclusions: In patients with a diagnosis of hypothyroidism, no evidence was found to suggest a clinically meaningful difference in the pattern of long term health outcomes (all cause mortality, atrial fibrillation, ischaemic heart disease, heart failure, stroke/transient ischaemic attack, fractures) when TSH concentrations were within recommended normal limits. Evidence was found for adverse health outcomes when TSH concentration is outside this range, particularly above the upper reference value.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

In UK primary care patients with incident hypothyroidism, TSH concentrations within the recommended normal range were not associated with clinically meaningful differences in long-term mortality, cardiovascular disease, or fracture outcomes. Adverse outcomes were seen mainly when TSH was outside normal limits, especially above 10 mIU/L.

Key findings

  • Compared with TSH 2-2.5 mIU/L, high TSH (>10 mIU/L) was associated with increased ischaemic heart disease (HR 1.18, 95% CI 1.02 to 1.38; P=0.03) and heart failure (HR 1.42, 95% CI 1.21 to 1.67; P<0.001).
  • Low TSH was associated with lower heart failure risk: HR 0.79 (0.64 to 0.99; P=0.04) for TSH <0.1 mIU/L and HR 0.76 (0.62 to 0.92; P=0.006) for 0.1-0.4 mIU/L.
  • Mortality was increased at both low and high TSH: HR 1.18 (1.08 to 1.28; P<0.001) for <0.1 mIU/L, HR 1.29 (1.22 to 1.36; P<0.001) for 4-10 mIU/L, and HR 2.21 (2.07 to 2.36; P<0.001) for >10 mIU/L.
  • Fragility fracture risk was increased at TSH >10 mIU/L (HR 1.15, 95% CI 1.01 to 1.31; P=0.03); no association was found for all fractures.

Methods

  • Retrospective cohort study using The Health Improvement Network (THIN), a UK primary care electronic records database, including adults with incident hypothyroidism from 1 January 1995 to 31 December 2017.
  • The analysis included 162,369 patients with hypothyroidism and 863,072 TSH measurements; median follow-up was 6 years, and 23.2% were men and 76.8% women.
  • TSH was modelled as a time-varying categorical covariate (annual mean; reference 2-2.5 mIU/L) in extended Cox proportional hazards models for ischaemic heart disease, heart failure, stroke/TIA, atrial fibrillation, all fractures, fragility fractures, and mortality, adjusted for baseline covariates; subgroup analyses were by age and sex.

Limitations

  • The paper states that it did not differentiate cause of hypothyroidism; assay variability, interference, macro-TSH, age-related TSH shifts, and obesity may affect the sample; some subclinical hypothyroidism may have been miscoded; baseline covariates may have varied over time; median follow-up of 6 years may not capture all long-term outcomes; cause-specific mortality is not recorded in THIN; reverse causality is possible; and osteoporosis is poorly recorded.
  • The paper also notes that pituitary disease was not excluded in the primary analysis, although a sensitivity analysis excluding 1,416 (0.9%) patients with pituitary disease had no effect on mortality findings.
  • Evident from the text: this is an observational database study, so residual confounding cannot be excluded, and reliance on Read codes and primary care records may introduce misclassification.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1136/bmj.l4892

Cites

52 of 52 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

0 of 23 cited sources checked · 0 supported · 0 flagged

  • Probably not a substantial claim. 25
  • It may state two separate claims as one. 24
  • The quote only partly states this claim. 4
41 of 41
  • The authors state this as an assumption.

    The remaining TSH categories (0.1-0.4 and 4-10 mIU/L) include subclinical thyroid dysfunction.

    “We assumed the remaining categories (TSH 0.1-0.4 and 4-10 mIU/L) to include subclinical thyroid dysfunction, serving both ease of interpretation and biological plausibility.”
  • The paper relies on this without support.

    Determining an individual's set point for TSH is not part of routine clinical practice.

    “but determining an individual’s set point is not part of routine clinical practice, and replacement treatment is generally targeted in a wide reference range.”
  • The paper relies on this without support.

    TSH concentrations in the wide target range may be achieved by different doses of levothyroxine.

    “TSH concentrations in this wide target range may be achieved by different doses of levothyroxine.”
  • The paper relies on this without support.

    Lifelong treatment with thyroid hormone is needed when persistent thyroid hormone deficiency is confirmed.

    “Lifelong treatment with thyroid hormone (replacement therapy) is needed when the diagnosis of persistent thyroid hormone deficiency is confirmed;”
  • The paper relies on this without support.

    No specific optimal target for thyroid stimulating hormone (TSH) concentration exists in the context of thyroid hormone replacement.

    “No specific optimal target for thyroid stimulating hormone (TSH) concentration exists in the context of thyroid hormone replacement”
  • The paper relies on this without support.

    Whether variation in TSH concentration within normal limits may significantly affect patients' outcomes remains unclear.

    “Whether variation in TSH concentration within normal limits may significantly affect patients’ outcomes remains unclear”
6 of 6

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Abstract overstates the number of patients included in the analysis

    Minor

    The abstract says 162,369 patients were included, but the Results section says 1,930 of those patients were excluded, leaving 160,439 included patients.

1 of 1

Citations

Cites

1 retracted

Flagged first, then by citations

Show all 54 references

2 of the 54 references couldn’t be matched to a known paper.

Cited by

Sorted by citations

See all 139

Metadata

Authors
Thayakaran, R., Adderley, N. J., Sainsbury, C., Torlinska, B., Boelaert, K., Šumilo, D., Price, M., Thomas, G. N., Toulis, K. A., & Nirantharakumar, K.
Affiliations
  • University of Birmingham (GB)
  • NHS Greater Glasgow and Clyde (GB)
  • 424 General Military Hospital (GR)
  • Health Data Research UK (GB)
Corresponding author
Nirantharakumar, Krishnarajah
Venue
BMJ
Publisher
BMJ
Published
2019-09-03
Volume
366
Pages
l4892
ISSN
  • 1756-1833 (ISSN-L)
  • 0959-8138
OpenAlex
W2971614705
Cited by
138
References
54
Citations by year
2026: 9 · 2025: 18 · 2024: 30 · 2023: 16 · 2022: 23 · 2021: 27 · 2020: 12 · 2019: 2
FWCI
12.98
Type
journal article
Language
en
Open access
Locations
  • BMJ (publishedVersion, cc-by-nc)
  • PubMed Central (publishedVersion, cc-by-nc)
  • PubMed (publishedVersion)
  • HighWire Press Open Archive (submittedVersion)
  • University of Birmingham Research Portal (University of Birmingham) (submittedVersion, cc-by-nc)
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 › Hormonal and reproductive studies
Keywords
hypothyroidism, thyroid-stimulating hormone, thyroid hormone replacement, levothyroxine, all-cause mortality, cardiovascular disease, ischemic heart disease, heart failure, stroke, atrial fibrillation, fracture, fragility fractures, TSH suppression, time-varying covariates, primary care, Health Improvement Network, health outcomes, dose-response relationship
MeSH terms
Adult, Aged, Cardiovascular Diseases, Female, Humans, Hypothyroidism, Longitudinal Studies, Male, Middle Aged, Reference Values, Retrospective Studies, Risk Factors, Thyroid Gland, Thyrotropin, Thyroxine, Fractures, Bone

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

A language model drew the claims from the paper on 2026-10-07, under version 3 of the claim definition (model deepseek-v4.1-flash, prompt extract-v3).

A second model labelled each claim on 2026-10-07 (model jev-1.13-20260917, definition revision gold-guideline-v0.2).

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review