Low goitre prevalence among users of oral contraceptives in a population sample of 3712 women.
OBJECTIVE
Goitre occurs primarily in women. As oestrogens may be an aetiologic factor, the use of oral contraceptives (OC) could be associated with an increased risk of goitre. This is supported by experimental data, but a recent population study suggested decreased thyroid volumes among users of OC.


METHODS
Cross-sectional, observational study.


METHODS
A random population sample of 3712 women from two Danish cities.


METHODS
Ultrasound and clinical examination of the thyroid, measurement of serum TSH, T3, T4 and thyroglobulin, and personal interviews with registration of use of OC or post-menopausal oestrogen therapy. Data were analysed in linear models and logistic regression adjusting for age and iodine status.


RESULTS
Thyroid volume was lower among users than non-users of OC, 11.1 ml vs. 12.1 ml (P < 0.001). Use of OC was correspondingly associated with a reduced prevalence of thyroid enlargement on ultrasound (odds ratio 0.53, 95% confidence interval 0.37-0.74) and of palpable and visible goitre (OR 0.24, 95% CI 0.07-0.81). Serum TSH was 1.24 mU/l in non-users of OC and 1.35 mU/l in users (P = 0.002). The percentage of goitre cases prevented by OC compared to a hypothetical population without use of OC was 29%. Post-menopausal oestrogen therapy showed similar, but statistically non-significant, associations.


CONCLUSIONS
Use of oral contraceptives was associated with a lower thyroid volume and reduced risk of goitre, and clinically evident goitre was four times more frequent among non-users than among users of oral contraceptives.
Knudsen
Nils
N
Department of Internal Medicine, Bispebjerg Hospital, Copenhagen, Denmark. nk01@bbh.hosp.dk
Bülow
Inge
I
Laurberg
Peter
P
Perrild
Hans
H
Ovesen
Lars
L
Jørgensen
Torben
T
D000293:Adolescent; D000328:Adult; D000368:Aged; D003278:Contraceptives, Oral, Hormonal / Q000008:administration & dosage*; D003430:Cross-Sectional Studies; D003718:Denmark / Q000453:epidemiology; D015914:Estrogen Replacement Therapy; D005260:Female; D006042:Goiter / Q000175:diagnosis / Q000453:epidemiology*; D006801:Humans; D007455:Iodine / Q000097:blood; D016015:Logistic Models; D008875:Middle Aged; D015995:Prevalence; D012306:Risk; D013961:Thyroid Gland / Q000000981:diagnostic imaging; D013972:Thyrotropin / Q000097:blood; D014463:Ultrasonography
D003278:Contraceptives, Oral, Hormonal; D013972:Thyrotropin; D007455:Iodine