title: False-positive crystals in urine from contamination by Multistix 10 SG reagent strips for urinalysis.
abstract: Dipstick testing of urine is commonly performed as part of point-of-care testing. Unless separate aliquots are used for dipstick testing, substances may be eluted from the test strip and contaminate patient samples. Such contamination has the potential to lead to interference in subsequent assays if the contaminated specimen is sent to the central laboratory for additional testing. We report our identification of refractile but not birefringent needle-shaped crystals as contaminants from prior contact of urine samples with the nitrite pad in the Multistix 10 SG Reagent Strips for Urinalysis (Siemens Healthcare Diagnostics, Deerfield, IL, USA). Educating clinicians who perform point-of-care testing outside the central laboratory is essential to eliminate this preanalytic artifact.
authors.affiliation: Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA.
authors.forename: Ji Yeon
authors.initials: JY
authors.lastname: Kim
authors.forename: Svetal
authors.initials: S
authors.lastname: Patel
authors.forename: Anand S
authors.initials: AS
authors.lastname: Dighe
mesh_terms: D016477:Artifacts; D003460:Crystallization; D004866:Equipment Contamination; D005189:False Positive Reactions; D006801:Humans; D009573:Nitrites; D011934:Reagent Strips; D016482:Urinalysis / Q000295:instrumentation / Q000379:methods*
chemical_list: D009573:Nitrites; D011934:Reagent Strips