SEX AND AGE CORRELATED REFERENCE VALUES OF SERUM THYROGLOBULIN MEASURED BY A MODIFIED RADIOIMMUNOASSAY

Abstract

ABSTRACT The aim of the present investigation was to describe variations in serum thyroglobulin in relation to sex and age in a group of normal persons. The method used was a modified double antibody radioimmunoassay characterized by pre-incubation at 37°C of standard or sample with antiserum, resulting in a reduced total incubation time. Both sensitivity and precision were comparable to other published methods. Of the 152 blood-donors initially investigated, 7 were excluded due to the presence of antithyroglobulin antibodies as evidenced by a radioassay. Both sexes were equally represented with an even distribution of ages from 20-65 years. Increased serum thyroglobulin with increasing age was demonstrated, the correlation being significant in women (Kendall's τ, P < 0.001). Detectable concentrations of serum thyroglobulin (above 1.7 μg/l) were found in 94 %. Based on the logarithmic transformation, the upper reference limits were determined for men ≦ 40 years: 36 μg/l, > 40 years: 44 μg/l (difference between groups not significant, P > 0.05), and for women ≦ 40 years: 30 μg/l, > 40 years: 60 μg/l (significant difference, P < 0.005).