Open AccessA proposed method for assessing plasma hypertonicity in vivo
Author(s) -
J D Stookey,
Maurice B. Burg,
D E Sellmeyer,
J. E. Greenleaf,
Allen I. Arieff,
Luc Van den hove,
Christopher D. Gardner,
JC King
Publication year - 2006
Publication title -
european journal of clinical nutrition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.024
H-Index - 157
eISSN - 1476-5640
pISSN - 0954-3007
DOI - 10.1038/sj.ejcn.1602481
Subject(s) - hematocrit , in vivo , endocrinology , mean corpuscular volume , medicine , chemistry , red blood cell , biology , microbiology and biotechnology
Indices of plasma hypertonicity, elevated plasma concentrations of solutes that draw fluid out of cells by osmosis, are needed to pursue hypertonicity as a possible risk factor for obesity and chronic disease. This paper proposes a new index that may be more sensitive to mild hypertonicity in vivo at a point in time than traditional measures. The index compares mean corpuscular volume (MCV) estimates from diluted (in solution by automated cell counter) and nondiluted blood (calculated from manual hematocrit, MCV=Hct/RBC*10(6)). A larger Auto vs Manual MCV (>2 fl) in vitro indicates hypertonicity in vivo if the cell counter diluent is isotonic with the threshold for plasma vasopressin (PVP) release and PVP is detectable in plasma (>0.5 pg/ml). To evaluate this principle of concept, hypertonicity was induced by 24-h fluid restriction after a 20 ml/kg water load in four healthy men (20-46 years). Unlike serum and urine indices, the MCV difference-&-PVP index detected hypertonicity in all participants.