12 |
Klinisk Biokemi i Norden · 3 2019
Selenium in clinical medicine and medical
biochemistry
Jan Alexander
1
, Urban Alehagen
2
, Anders Larsson
3
and Jan Aaseth
4
1
Norwegian Institute of Public Health, Oslo, Norway
2
Division of Cardiovascular Medicine, Department of Medical and Health Sciences, Linköping
University, Linköping, Sweden
3
Department of Medical Sciences, Uppsala University, Uppsala, Sweden
4
Research Department, Innlandet Hospital Trust, Norway
Introduction
Selenium (Se) is an essential trace element that is
critical to the normal physiology of a wide range of
species, including humans (1,2). In humans, twenty-
five genes have been identified that encode for seleno-
proteins. All of them contain selenium as the amino
acid selenocysteine (SeCys) often denoted amino acid
no. 21. SeCys differs from cysteine by a single atom –
Se vs. S – conferring a lower pK
a
(5.2 versus 8.3) and
a higher reactivity of the functional selenol group,
which thereby can interact more rapidly with reactive
oxygen species, why several selenoproteins are part
of antioxidant enzyme system. A striking example
of deficiency is the occurrence of Keshan disease, an
endemic cardiomyopathy in certain areas of China
with severe Se deficiency, which is prevented with
large-scale Se supplementation (3). The selenoproteins
have a wide range of functions in the body and are
collectively essential for life, as demonstrated by the
mouse model with deletion of gene encoding the tRNA
for their synthesis, which results in embryonic letha-
Estimated Mean Selenium Intake (µg/day)
Figure 1.
Average daily selenium
intake in various countries (data
adapted from Fairweather-Tait et al.
2011(4-9).
0
20
40
60
80
100
120
Croatia
Serbia
Italy
Belgium
Germany
Poland
Denmark
France
UK
Austria
Sweden
Norway
Finland
USA
