Welcome to our website. It's always a work in progress and your feedback is welcome



Research Articles and Papers on:

Smoking and the thyroid

Free triiodothyronine is associated with smoking habit, independently of obesity, body fat distribution, insulin, and metabolic parameters.

J Endocrinol Invest. 2010 Dec;33(11):815-8. doi: 10.3275/7168. Epub 2010 Jul 13.

De Pergola G, Ciampolillo A, Alò D, Sciaraffia M, Guida P.
Internal Medicine, Endocrinology, Andrology, and Metabolic Disease, Department of Emergency and Organ Transplantation, University of Bari, School of Medicine, Policlinico, Via Putignani 236, Bari, Italy. g.depergola@endo.uniba.it

The aim of this study was to examine the relationship between thyroid hormones and smoking and several other parameters like age, gender, insulin, and anthropometric and metabolic parameters in subjects with a wide range of body mass index (BMI).

A total of 931 euthyroid normal weight (BMI<25.0 kg/m2), overweight and obese subjects (BMI ≥25.0 kg/m2), 663 women and 268 men, aged 18-68 yr, were investigated. Fasting TSH, free T3 (FT3), free T4 (FT4), insulin, glucose, and lipid serum levels were determined. Waist circumference was measured as an indirect parameter of central fat accumulation.

Smokers were younger (p<0.001) and showed higher FT3 (p<0.01), and triglyceride (p<0.01) levels and lower glucose (p<0.01) and HDL (p<0.001) concentrations than non smoking subjects. FT3 levels were directly associated with BMI (p<0.001), waist circumference (p<0.001), insulin (p<0.001), and triglyceride (p<0.01) levels and negatively correlated with age (p<0.001) and HDL-cholesterol levels (p<0.001). When a multiple regression analysis was performed with FT3 levels as the dependent variable, and smoking, age, gender, and TSH, insulin, triglyceride, and HDL-cholesterol serum concentrations as independent variables, FT3 levels maintained an independent positive association with smoking (p<0.05), age (p<0.001), male sex (p<0.001), waist circumference (p<0.05), and insulin levels (p<0.001).

Smoking increases FT3 levels independently of age, gender, obesity, body fat distribution and metabolic parameters.



The association of cigarette smoking with serum TSH concentration and thyroperoxidase antibody.

Exp Clin Endocrinol Diabetes. 2012 Feb;

Mehran L, Amouzgar A, Delshad H, Azizi F.

Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran.

Although several studies have found an association between tobacco smoking and thyroid disorders such as Graves' disease, Graves' ophtalmopathy, goiter and thyroid multi nodularity, the effect of smoking on thyroid function is controversial.

The aim of this study was to evaluate the association between smoking and serum TSH concentration and the presence of thyroperoxidase antibody (TPO Ab) in Tehranian adults.

In this cross sectional community based survey, 1,581 randomly selected subjects with no history of thyroid disorders were studied within the framework of Tehran Lipid and Glucose Study. Serum TSH and TPOAb were measured in a fasting serum sample. Weight and height were measured and BMI was calculated. Smokers were classified into ever and never smokers based on the declaration of participants.

Mean Ln TSH values in the ever smoker (0.36±0.82) was significantly lower than the never smoker (0.6±0.82) group (p<0.001) even after adjustment for age and BMI. The odds ratio for hypothyroidism (TSH>5.8) was 0.4 in the ever smoker group compared to the never one (odds ratio 0.4, 95% CI=0.2-0.8). The frequency of positive TPOAb in never smokers was significantly higher than ever smokers (%13.5 vs. % 6.7, p<0.001).

The results suggest that smoking is associated with decreased serum TSH concentrations, lower risk of hypothyroidism and possibly with a lower frequency of thyroid auto immunity.

© J. A. Barth Verlag in George Thieme Verlag KG Stuttgart · New York.




Smoking May Decrease the Incidence of Thyroid Cancer in Postmenopausal Women

Clin Thyroidol 2012;24:8–9
Jerome M. Hershman

Kabat GC, Kim MY, Wactawski-Wende J, Rohan TE. Smoking and alcohol consumption in relation to risk of thyroid cancer in postmenopausal women. Cancer Epidemiol 2012;36:335-40. Epub April 22, 2012; doi: 10.1016/j.canep.2012.03.013


Thyroid cancer is the eighth most common cancer in women, and its incidence is increasing. No risk factors other than ionizing radiation have been identified for differentiated thyroid cancer. Studies of the relationship of thyroid cancer with cigarette smoking have been contradictory. Most studies of alcohol consumption have found no association with thyroid cancer. The current study is an analysis of the association of smoking and alcohol consumption in the Women's Health Initiative (WHI), a large multicenter study designed to advance the understanding of causes of major chronic diseases in postmenopausal women.

The study assessed the association of smoking and alcohol intake with risk of thyroid cancer in a cohort of 159,340 women enrolled in the WHI. A self-administered questionnaire recorded smoking habits with regard to ever smoking, age at starting, whether a current smoker, age at quitting, and number of cigarettes smoked per day. The number of alcoholic drinks per month, week, and day were also recorded. Cox proportional-hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals for the associations of smoking and alcohol intake with risk of thyroid cancer. Tests were also performed for the interaction of alcohol intake and smoking and thyroid cancer risk.

There were 331 cases of thyroid cancer, of which 276 were papillary thyroid cancers (PTCs). At baseline, patients with thyroid cancer were significantly younger (61.9 vs. 63.2 years) and taller (163.3 vs. 161.8 cm), had lower alcohol intake, and had a much greater frequency of thyroid nodules and goiter than patients who did not have cancer. Women who had smoked for <20 years were at elevated risk for thyroid cancer (HR, 1.35; 95% CI, 1.05 to 1.74). Smokers of >40 pack-years had a significantly reduced risk of PTC based on 8 exposed cancer cases (vs. 12,300 smokers who did not have cancer) (HR, 0.44; 95% CI, 0.21 to 0.89). Current smokers (11,200) had a reduced risk for PTC (HR, 0.34; 95% CI, 0.15 to 0.78), but there were only 6 patients with PTC for comparison.

Alcohol consumption was not associated with an altered risk of thyroid cancer, nor was the amount of alcohol associated with the risk of thyroid cancer. There was no interaction between smoking and drinking on the risk of thyroid cancer.

"Our findings suggest that current smoking and having higher pack-years of exposure are associated with a modestly reduced risk of thyroid cancer, whereas alcohol consumption does not appear to affect risk."

The full article includes an Analysis and Commentary, plus References. Click the link below to download the full article in PDF format:


Weight Gained after Smoking Cessation May Be Caused by Onset of Hypothyroidism

Clin Thyroidol 2012;24:10–11
Jorge H. Mestman

Carlé A, Bülow Pedersen I, Knudsen N, Perrild H, Ovesen L, Banke Rasmussen L, Jørgensen T, Laurberg P. Smoking cessation is followed by a sharp but transient rise in the incidence of overt autoimmune hypothyroidism—a population-based, case–control study. Clin Endocrinol 2012;77:764-72.


Current smoking is associated with a low prevalence of thyroid autoantibodies; however, the thyroid autoantibody level increases following smoking withdrawal and could be a risk factor for the development of hypothyroidism. The aim of the authors was to assess the association between smoking habits (smoking cessation in particular) and the development of autoimmune hypothyroidism.

This was a population-based, case–control study conducted from 1997 through 2000. The Danish Investigation of Iodine Intake and Thyroid Diseases (DanThyr) prospectively identified all patients with newly diagnosed overt hypothyroidism in a Danish population. A total of 140 (59.5% of all patients diagnosed with autoimmune hypothyroidism) agreed to participate. Patients were identified prospectively by population monitoring (2,027,208 person-years of observation) of all thyroid-function tests performed in the two well-defined geographical areas: Aalborg, which had moderate iodine deficiency, and Copenhagen, which had only mild iodine deficiency. All subjects with a high serum TSH (>5.0 mU/L) in combination with a low T4 estimate identified by the register were individually scrutinized to verify or disprove new overt hypothyroidism; subjects with antibody concentrations above the functional sensitivity given by the manufacturer (TPOAb, >30 kU/L, TgAb, >20 kU/L) were regarded as antibody-positive. Only patients with primary autoimmune hypothyroidism were considered for this study. Individually, age-, sex-, and region-matched euthyroid controls (n = 560) were simultaneously included from the same population. Participants gave details on smoking habits, including smoking withdrawal, and other lifestyle factors. Smoking habits were verified by measuring urinary cotinine, a nicotine metabolite.

Incident hypothyroidism was very common in people who had recently stopped smoking (odds ratio [OR] vs. never smokers (95% CI): <1 year after quitting smoking, 7.36 [2.27 to 23.9]; 1 to 2 years, 6.34 [2.59 to 15.3]; 3 to 10 years, 0.75 [0.30–1.87]; >10 years, 0.76 [0.38 to 1.51]). Results were consistent in both sexes and irrespective of age. Within 2 years after smoking cessation, the percentage of cases of hypothyroidism attributable to smoking cessation was 85%. Current smoking was not associated with an altered risk of overt hypothyroidism (OR, 0.92 [0.57 to 1.48]). The authors found no difference in years of smoking, pack-years of smoking, or preferred type of tobacco consumption.

The risk of receiving a diagnosis of overt autoimmune hypothyroidism is increased more than six-fold in the first 2 years after smoking cessation. Clearly, smoking cessation is vital to prevent death and severe disease. However, awareness of hypothyroidism should be high in people who have recently quit smoking, and virtually any report of symptoms should prompt thyroid-function testing.


The full article includes an Analysis and Commentary, plus References. Click the link below to download the full article in PDF format:



Tobacco Smoking and Thyroid Function

Bjørn O. Åsvold, MD; Trine Bjøro, MD, PhD; Tom I. L. Nilsen, PhD; Lars J. Vatten, MD, PhD
Arch Intern Med. 2007;167(13):1428-1432.

The association between tobacco smoking and thyroid function is not completely understood so researchers conducted a study between August 15, 1995, and June 18, 1997.

The researchers calculated the average TSH of 20,479 women and 10,355 men without previously known thyroid disease and they also checked how often hypothyroidism and hyperthyroidism was found in current, former, and never smokers.

Among women, the average TSH level was lower in current (1.33mIU/L) and former smokers (1.61mIU/L) compared with never smokers (1.66mIU/L).

Similarly, among men, the average TSH level was lower in current (1.40mIU/L) and former smokers (1.61mIU/L) compared with never smokers (1.70mIU/L).

In former smokers, their TSH levels increased gradually since they stopped smoking.

Among current smokers, moderate daily smoking was associated with higher TSH levels than heavier smoking.

In women, the frequency of overt (clearly diagnosed) hypothyroidism was lower in current smokers compared with never smokers  whereas the frequency of overt hyperthyroidism was higher among current smokers.

The associations of smoking related to subclinical thyroid dysfunction were similar to those for overt thyroid disease.

The researchers concluded that the study indicated that smoking is negatively associated with hypothyroidism but positively associated with hyperthyroidism. In other words, when people smoke, it causes hyperthyoidism.  They also felt that smoking may have reversible effects on thyroid function - once people stop smoking, their thyroid levels return to normal. They reported, for the first time, that there was a lower frequency of overt hypothyroidism among current smokers.