title: [Interconversion of the results for erythrocyte zinc protoporphyrin expressed in different units].
abstract: As stated in a recent document of the National Committee for Clinical Laboratory Standards (NCCLS Document C42-P, April 1995), expression of the results of erythrocyte zinc protoporphyrin (ZPP) in different units is a main source of confusion which may hamper the wide use of this test. The possible inter-conversion of the ZPP values expressed as microgram/g Hb, microgram/dL blood and microgram/dL red cells was assessed. It was found that in all cases, despite a good correlation between these values (r > or = 0.939), the error of the estimation was higher than allowed by the American College of Pathologists criteria. Such findings show that ZPP values expressed in different units cannot be inter-converted as a function of the corresponding regression equation. Similarly, the use of hematofluorometers with an analogic-digital converter to express results as microgram ZPP/ dL blood might pose an additional source of error.
authors.affiliation: Laboratorio Central, Hospital General de Galicia-Clínico Universitario, Santiago de Compostela.
authors.forename: L F
authors.initials: LF
authors.lastname: Pérez
authors.forename: E
authors.initials: E
authors.lastname: Mateo
authors.forename: J
authors.initials: J
authors.lastname: Pedreira
authors.forename: J C
authors.initials: JC
authors.lastname: Tutor
mesh_terms: D000465:Algorithms; D001774:Blood Chemical Analysis / Q000592:standards; D004912:Erythrocytes / Q000737:chemistry*; D006801:Humans; D011524:Protoporphyrins / Q000097:blood*; D014894:Weights and Measures
chemical_list: D011524:Protoporphyrins; C017803:zinc protoporphyrin