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VALIDITY OF ANDROGEN ASSAYS.
Tom Trinick
Consultant in Chemical Pathology and Physician, The Laboratories,
The Ulster Hospital, Dundonald, Belfast Bt16 0RH Tom.Trinick@n-i.nhs.uk
The uses that androgen measurements are put to will be discussed
and the importance of accurate measurement of androgens will be
discussed. Preanalytical factors include the effect of circadian
rhythm. The increased testosterone synthesis at night plus the haemodilution
of recumbency can raise bioavailable testosterone by 57%, free testosterone
by 68% and total testosterone by 45%. Seasonal variation shows testosterone
peaks in the autumn and is lowest in the summer - 19%TT and 31%
FT. Diet can be important as SHBG is decreased by high protein high
fat diets like the Atkins diet and is increased by vegetarian and
high fibre diets. Alcohol in low doses raises testosterone by 19%
in men and women. Acute alcohol intoxication can reduce testosterone
levels by 23% for up to 22 hours. Low intensity exercise can increase
androgen levels, even transiently; high or extreme levels of exercise
tend to depress androgen levels. Reduced androgen levels seen in
serious illness - trauma, coronary heart disease and liver disease.
The MMAS showed that apparently healthy men had levels of testosterone
15% above the rest of the group. Excessive or unpleasant physical
or mental stress can activate the hypothalamo-pituitary-adrenal
axis and reduce the amount or activity of androgens.
These preanalytical issues will be discussed as well as analytical
and post analytical factors.
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