Glattre 1989

Methods	Matched, nested case‐control study Country: Norway
Participants	Participants: 100,000 men and women Inclusion criteria: serum available at Janus serum bank (Norwegian serum bank which is consolidated from several sources and maintained by the Norwegian Cancer Society for research purposes) Recruitment: 1972 to 1985 Outcome assessment: end of 1985 Number of cases: thyroid cancer: 43 (male/female: 12/31) Case definition: incidence Years of follow‐up: 0.0 to 14.0 years Type of selenium marker: serum
Interventions	d.n.a.
Outcomes	Statistical methods: conditional logistic regression Variables controlled by matching: age, gender, year of sample collection, county of residence
Risk estimates [95% CI]	Reference category: highest tertile Results: Thyroid cancer  both genders: lowest tertiles: OR 7.7 (95% CI 1.3 to 44.7) men: lowest tertiles: OR 6.5 (95% CI 0.2 to 201.9) women: lowest tertiles: OR 8.3 (95% CI 0.9 to 78.5)
Selenium levels in exposure categories	lowest tertile: ≤ 1.25 µmol/l highest tertile: ≥ 1.65 µmol/l
Notes