Variability of leptin values measured from different sample matrices

Leptin concentrations are usually determined in serum or EDTA-treated plasm a. Our aim was to evaluate the precision and accuracy of leptin measurement from serum and various kinds of plasma. Blood samples were collected from healthy volunteers and divided into aliquots of serum and plasma with admin istration of K-2-EDTA, citrate, fluoride and lithium-heparinate, respective ly. Leptin concentrations were measured by a specific radioimmunoassay, The re were clear differences between the leptin values from the different matr ices. The coefficient of variation (CV) was highest in serum samples (CV: 1 1.9 %) and very low in K-2-EDTA-treated plasma samples (CV: 5.3%). Leptin m easurements from serum yielded significantly lower results than the respect ive K-2-EDTA-treated plasma samples (p < 0.05). The measurement in Li-hepar inate-treated plasma revealed similar results to that in K-2-EDTA-treated p lasma. The lowest CV was determined in fluoride-treated plasma (5.2%). A hi gher CV was determined in citrate-treated plasma (5.8%) and the values were about 25% lower than in the respective K-2-EDTA-treated plasma samples (p < 0.0001). Lower leptin measurements in citrate-treated plasma may partiall y, but not in total, be a consequence of dilution by anticoagulating additi ves. Because of the low CV K-2-EDTA- and Li-heparinate-treated plasma sampl es appear most reliable for the measurement of leptin, The usage of these s ample matrices is therefore recommended. Copyright (C) 2001 S. Karger AG, B asel.