title: Testing Na+in blood.
abstract: Both direct potentiometry and indirect potentiometry are currently used for Na+testing in blood. These measurement techniques show good agreement as long as protein and lipid concentrations in blood remain normal. In severely ill patients, indirect potentiometry commonly leads to relevant errors in Na+estimation: 25% of specimens show a disagreement between direct and indirect potentiometry, which is ≥4 mmol/L (mostly spuriously elevated Na+level due to low circulating albumin concentration). There is a need for increased awareness of the poor performance of indirect potentiometry in some clinical settings.
authors.affiliation: Department of Pediatrics, University Children's Hospital of Bern, Inselspital, Bern, Switzerland; Pediatric Pharmacology and Pharmacogenetics, Hôpital Robert Debré, Paris, France.
authors.forename: Sebastiano A G
authors.initials: SA
authors.lastname: Lava
authors.affiliation: Pediatric Department of Southern Switzerland, Bellinzona, Switzerland; Università della Svizzera Italiana, Lugano, Switzerland.
authors.forename: Mario G
authors.initials: MG
authors.lastname: Bianchetti
authors.affiliation: Foundation IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Pediatric Emergency Department, Milan, Italy.
authors.forename: Gregorio P
authors.initials: GP
authors.lastname: Milani