Pre-analytical variables evaluation in laboratory tests of patients attended at the Vitória da Conquista Central laboratory, Bahia, Brazil

Abstract

ABSTRACT Introduction: Laboratory tests are intended to provide information necessary to clarify diagnoses or specific situations that cannot be elucidated by other means. Laboratory analyses are subject to several interferences. Even healthy individuals could suffer variations in laboratory tests due to biological factors, which may lead to misinterpretation of the results. Objective: Assess the pre-analytical variables in patients’ laboratory tests at the Vitória da Conquista Central Laboratory, Bahia, Brazil. Material and method: This is a cross-sectional study with a descriptive approach and the use of a questionnaire as a research instrument. Data were collected through individual interviews, carried out at the laboratory. Results: The sample consisted of 425 patients, with female predominance (76.5%). Regarding patient instructions for laboratory tests, 94.6% had not been given any previous guidance, and 68.5% used some kind of medication, which could produce alterations in the exams. The use of the antihypertensive agents captopril, enalapril, hydrochlorothiazide or propranolol was associated with increased serum urea [odds ratio (OR) = 7.2, confidence interval (CI) = 95%, 1.87-27.58; p = 0.002], and smoking was associated with increased red blood cells count (OR = 3.7, CI = 95%, 0.86-15.75; p = 0.02). Conclusion: The findings indicate that pre-analytical variables remain an important focus for attention to the clinical laboratory. The correct data collection of patients’ conditions is critical to support the post-analytical phase with useful information for the production of reliable exams and serve as a useful interpretation to diagnosis.

Keywords

• pre-analytical variables
• interference
• laboratory examination