Verena Gounden1, David B Sacks1, Zhen Zhao2. 1. Department of Laboratory Medicine, NIH Clinical Center, Building 10, Room 2C-249, Bethesda, MD 20892 USA. 2. Department of Laboratory Medicine, NIH Clinical Center, Building 10, Room 2C-249, Bethesda, MD 20892 USA. Electronic address: zhen.zhao@nih.gov.
Abstract
BACKGROUND: A falsely high cerebrospinal fluid (CSF) total protein (TP) result measured by pyrogallol red (PGR) method was suspected to be caused by preparation of the collection site with povidone-iodine (PVP-iodine) solution. METHODS: CSF TP was evaluated for interference in samples with different final concentrations of PVP-iodine (up to 0.25% PVP and 0.025% iodine) or iodine alone (up to 0.025% iodine) using three methods: PGR, modified biuret and benzethonium chloride (BZTC). Interference exceeding ±20% of the baseline value is considered clinically significant according to the criterion defined by the College of American Pathologists. RESULTS: There were positive interference with the PGR method and negative inference for the BZTC method in CSF samples spiked with PVP-iodine. The PVP-iodine (up to 0.25% PVP and 0.025% iodine) did not cause a clinically significant interference with the modified biuret method. PVP alone without iodine caused a positive interference with the PGR method but did not interfere with the modified biuret or the BZTC method. When the samples were spiked with iodine alone, none of the three methods was affected (change<20%) by iodine concentration up to 0.025%. CONCLUSIONS: Contamination of CSF specimens with PVP-iodine can lead to interference with CSF TP measurements using PGR or BZTC methods. Published by Elsevier B.V.
BACKGROUND: A falsely high cerebrospinal fluid (CSF) total protein (TP) result measured by pyrogallol red (PGR) method was suspected to be caused by preparation of the collection site with povidone-iodine (PVP-iodine) solution. METHODS: CSF TP was evaluated for interference in samples with different final concentrations of PVP-iodine (up to 0.25% PVP and 0.025% iodine) or iodine alone (up to 0.025% iodine) using three methods: PGR, modified biuret and benzethonium chloride (BZTC). Interference exceeding ±20% of the baseline value is considered clinically significant according to the criterion defined by the College of American Pathologists. RESULTS: There were positive interference with the PGR method and negative inference for the BZTC method in CSF samples spiked with PVP-iodine. The PVP-iodine (up to 0.25% PVP and 0.025% iodine) did not cause a clinically significant interference with the modified biuret method. PVP alone without iodine caused a positive interference with the PGR method but did not interfere with the modified biuret or the BZTC method. When the samples were spiked with iodine alone, none of the three methods was affected (change<20%) by iodine concentration up to 0.025%. CONCLUSIONS: Contamination of CSF specimens with PVP-iodine can lead to interference with CSF TP measurements using PGR or BZTC methods. Published by Elsevier B.V.
Entities:
Keywords:
Cerebrospinal fluid; Iodine; Povidone; Pre-analytical interference; Total protein
Authors: Giuseppe Lippi; Jeffrey J Chance; Stephen Church; Paola Dazzi; Rossana Fontana; Davide Giavarina; Kjell Grankvist; Wim Huisman; Timo Kouri; Vladimir Palicka; Mario Plebani; Vincenzo Puro; Gian Luca Salvagno; Sverre Sandberg; Ken Sikaris; Ian Watson; Ana K Stankovic; Ana-Maria Simundic Journal: Clin Chem Lab Med Date: 2011-04-25 Impact factor: 3.694