The variability of normal ranges in different laboratories and the occurrence of occasional
elevated values of β-TG and PF-4 in normal subjects are well established.
We examined the influence of factors such as age, sex, smoking, exercise, oral contraceptives
and day-to-day variation in 148 healthy subjects. The β-TG and PF-4 assays were performed
by commercial RIA’s modified by utilizing an EDTA- PGE1 -theophylline mixture as anticoagulant.
The statistical method used to compare our groups was a student t-test after log transformation
of the data. Our baseline control group (N=63) were non smokers and not taking oral
contraceptives (O/C) or any medications. There was no difference between sexes or
a significant change with increasing age, although the mean β-TG and PF-4 does increase
in cohosts of 20 years. [<30 years (21.65±8.35)(SD), 30-50 years (24.32±10.94) >50
years (27.88±14.3)-β-TG data].
Women on O/C were significantly different from those not on O/C for β-TG [35.06±22.45
(O/C) and 23.67±9.38 (N)] but not for PF-4 values [3.79±1.77 (O/C) and 3.91±1.63 (N)].
Strenuous exercise was the parameter that influenced both β-TG and PF-4 significantly,
showing an elevated value after exercise for both β-TG [81.9±31.4 v 26.73±10.91] and
PF-4 [7.08±1.71 v 3.73±1.91].
Day-to-day variations in β-TG and PF-4 were examined in 10 subjects for 7-10 days.
The coefficient of variation (CV) amongst these subjects was 21-51%. In athletes day-today
variation was the same unless a change in pattern of exercise occurred [CV-49-132%].
Our results confirm that parameters such as above do influence normal values and should
be taken into consideration in establishing a normal range.
It also indicates the β-TG is a more sensitive parameter for delineating differences
in physiological parameters in normal subjects than PF-4, and this may be applicable
to clinical studies.
