Research article

The role of selenium, vitamin C, and zinc in benign thyroid diseases and of selenium in malignant thyroid diseases: Low selenium levels are found in subacute and silent thyroiditis and in papillary and follicular carcinoma

Roy Moncayo^1,2 , Alexander Kroiss² , Manfred Oberwinkler² , Fatih Karakolcu² , Matthias Starzinger² , Klaus Kapelari³ , Heribert Talasz⁴ and Helga Moncayo¹

¹WOMED, Karl-Kapferer-Strasse 5, Innsbruck, Austria

²Clinical Department of Nuclear Medicine, Medical University of Innsbruck, Austria

³Clinical Department of Pediatrics, Medical University of Innsbruck, Austria

⁴Biocenter, Division of Clinical Biochemistry, Innsbruck Medical University, Austria

author email corresponding author email

BMC Endocrine Disorders 2008, 8:2doi:10.1186/1472-6823-8-2

Published:	25 January 2008

Abstract

Background

Thyroid physiology is closely related to oxidative changes. The aim of this controlled study was to evaluate the levels of nutritional anti-oxidants such as vitamin C, zinc (Zn) and selenium (Se), and to investigate any association of them with parameters of thyroid function and pathology including benign and malignant thyroid diseases.

Methods

This controlled evaluation of Se included a total of 1401 subjects (1186 adults and 215 children) distributed as follows: control group (n = 687), benign thyroid disease (85 children and 465 adults); malignant thyroid disease (2 children and 79 adults). Clinical evaluation of patients with benign thyroid disease included sonography, scintigraphy, as well as the determination of fT3, fT4, TSH, thyroid antibodies levels, Se, Zn, and vitamin C. Besides the routine oncological parameters (TG, TSH, fT4, ultrasound) Se was also determined in the cases of malignant disease. The local control groups for the evaluation of Se levels were taken from a general practice (WOMED) as well as from healthy active athletes. Blood samples were collected between 8:00 and 10:30 a.m. All patients lived in Innsbruck. Statistical analysis was done using SPSS 14.0. The H_o stated that there should be no differences in the levels of antioxidants between controls and thyroid disease patients.

Results

Among the thyroid disease patients neither vitamin C, nor Zn nor Se correlated with any of the following parameters: age, sex, BMI, body weight, thyroid scintigraphy, ultrasound pattern, thyroid function, or thyroid antibodies. The proportion of patients with benign thyroid diseases having analyte concentrations below external reference cut off levels were 8.7% of cases for vitamin C; 7.8% for Zn, and 20.3% for Se. Low Se levels in the control group were found in 12%. Se levels were significantly decreased in cases of sub-acute and silent thyroiditis (66.4 ± 23.1 μg/l and 59.3 ± 20.1 μg/l, respectively) as well as in follicular and papillary thyroid carcinoma. The mean Se level in the control group was 90.5 ± 20.8 μg/l.

Conclusion

The H₀ can be accepted for vitamin C and zinc levels whereas it has to be rejected for Se. Patients with benign or malignant thyroid diseases can present low Se levels as compared to controls. Low levels of vitamin C were found in all subgroups of patients.