TOPLINE:

In patients with Graves disease (GD), cigarette smoking was independently associated with greater disease severity, a higher risk for Graves orbitopathy, and an increased risk for relapse in a dose-dependent manner. Ex-smokers demonstrated outcomes similar to non-smokers, suggesting potential benefits of smoking cessation for disease management.

METHODOLOGY:

• Researchers in the UK conducted an observational cohort study to assess the dose-dependent association between smoking exposure and clinical outcomes in patients with GD.
• They evaluated 991 adults with newly diagnosed GD (mean age, 48.1 years; 82% women) and categorised them according to their smoking status (non-smokers [n = 491], ex-smokers [n = 232], and current smokers [n = 268]).
• Patients received standard antithyroid drug (ATD) therapy and were reviewed every 3-6 months, with treatment discontinued upon thyrotropin receptor antibody (TRAb) normalisation or on the basis of patient preference or adverse effects.
• Primary outcomes were disease severity at diagnosis (TRAb and thyroid hormone levels), presence of Graves orbitopathy, and relapse of hyperthyroidism at 12 months and in the long term after ATD cessation.
• Relapse was defined as recurrent biochemical hyperthyroidism (elevated free thyroxine/triiodothyronine levels with suppressed thyroid-stimulating hormone levels) with elevated TRAb levels after ATD withdrawal.

TAKEAWAY:

• Current smokers had higher TRAb levels than non-smokers and ex-smokers (8.0 vs 6.6 and 5.5 IU/L). Each 10-cigarette-per-day increase was associated with 9% higher TRAb levels (P = .04), with the association being linear (P for non-linearity = .20).
• The number of cigarettes smoked per day was significantly associated with free thyroxine levels (P = .0015), with a mild non-linear relationship. Free thyroxine levels decreased with increasing cigarette consumption up to approximately 10-15 cigarettes per day, then increased slightly at higher intensities.
• Compared with non-smokers, current smokers had 76% higher odds of Graves orbitopathy (adjusted odds ratio [aOR], 1.76; P = .007), with no difference observed for ex-smokers. Each 10-cigarette-per-day increase was linked to a 34% higher risk for the condition (aOR, 1.34; P = .02).
• At 12 months, each 10-cigarette-per-day increase was associated with an approximately 60% higher risk for relapse (P < .001). Soon after ATD withdrawal at 6 months, current smokers had a 24% higher risk for relapse (hazard ratio, 1.24; 95% CI, 1.05-1.47).

IN PRACTICE:

"Smoking cessation — or even reduction — represents a simple, safe, and low-cost therapeutic target that should remain central to comprehensive GD management," the authors wrote.

SOURCE:

This study was led by Sarah Forbes, MD, Department of Endocrinology, Gateshead Health NHS Foundation Trust, Tyne and Wear, England. It was published online on February 12, 2026, in The Journal of Clinical Endocrinology & Metabolism.

LIMITATIONS:

The study relied on self-reported smoking data, lacked data on passive smoking exposure, and had incomplete data on smoking behaviour changes during follow-up. The possibility of residual confounding cannot be excluded. A complete case analysis was used to evaluate missing data, which could have introduced bias.

DISCLOSURES:

This study did not receive any funding. No relevant conflicts of interest were disclosed by the authors.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.