S. Antonsen et al., ASPECTS OF PREANALYTICAL VARIATION OF LACTOFERRIN AND ELASTASE ALPHA-1-PROTEASE INHIBITOR COMPLEXES, Scandinavian journal of clinical & laboratory investigation, 53(3), 1993, pp. 263-274
A number of interesting applications of plasma elastase/al-protease in
hibitor complexes (ELA-PI) and lactoferrin (LAC) have recently been su
ggested. However, the clinical utility of these components often seems
to be low. This might be improved by minimizing the preanalytical var
iation, if possible. Therefore, we have evaluated the influence of var
ious aspects of sampling and handling conditions on the results obtain
ed when measuring ELA-PI and LAC. Blood samples from both healthy pers
ons as well as patients, who had undergone laparotomy the day before,
were investigated. We confirmed the previous observations of higher co
ncentrations of ELA-PI and LAC in serum compared to plasma. This was m
ore pronounced in patients than in healthy adults. In EDTA-blood the m
ost important change was seen in samples from patients when stored at
room temperature. In this situation increases of LAC concentrations of
50% and 100% following 2 and 5 h, respectively were found. This in vi
tro release of LAC was abolished when samples were stored on ice until
centrifugation within 5 h. In contrast, a statistically significant i
ncrease in ELA-PI of 10% was observed following storage on ice for 2h
of blood specimens drawn from healthy persons. EDTA-plasma obtained by
venous puncture following minimal stasis contained 10% higher concent
rations of LAC compared to samples drawn from intravenous catheters, w
hile no difference was observed in the case of ELA-PI. However, in one
individual prolonged venous stasis resulted in larger differences of
both LAC and ELA-PI. Different centrifugation conditions (1500 vs. 300
0 x g; room temperature vs. 4-degrees-C) did not influence concentrati
ons of LAC or ELA-PI measured, neither did eating a normal meal nor mo
derate physical activity (30 min walk). In conclusion, ELA-PI and LAC
should be measured in EDTA-plasma. Blood must be drawn by venous punct
ure applying minimal stasis or from indwelling venous catheters. Sampl
es for measuring LAC must be stored on ice until centrifugation. Separ
ation of plasma from cells should be performed as fast as possible, bu
t storage for up to 5 h can be accepted.