Journal of Lipid Research, Vol 26, 575-582, Copyright © 1985 by Lipid Research, Inc.
A convenient six-point blood sampling schedule for determining whole body cholesterol kinetics in humans
RB Dell, R Ramakrishnan, RH Palmer and DS Goodman
Parameters of total body cholesterol metabolism in humans can be determined
by using a three-pool model to analyze the turnover of plasma cholesterol
following the injection of radiolabeled cholesterol. In the past this
required a rigorous schedule of approximately 36 blood samples over a
10-month period. We have developed a convenient sampling schedule involving
only six large samples, each analyzed in sextuplicate. Such a reduction in
the frequency of samples is possible only when considerable confidence in
the model is available. In general, the simplified sampling strategy
depends upon considerable prior experience with the model, only moderate
biological error, and estimatable subject to subject variation in model
parameters. Because the timing of the samples is critical and because the
optimal times will differ for different subjects, the six-point strategy
involves using the first three samples (drawn at days 1, 7, and 24 or, for
hypercholesterolemic subjects, at days 1, 8, and 28) in conjunction with
results from previous studies to set the time for the next sample; the
process is reiterated for the last two points. In this study, we have
compared parameter estimates obtained by the new six-point schedule with
those obtained simultaneously (in the same, single turnover study) by the
old 36-point schedule in the same 26 subjects. Both schedules gave
comparable values. In particular, the coefficients of variation between
values obtained by the two methods for each of the four parameters for
which we have developed predictive equations were quite low: PR 1.5%, M1
4.1%, M3min 13%, Mtot min 4.3%. The simplified six-point schedule makes it
feasible to study long-term cholesterol turnover in substantial numbers of
patients.