Reference Interval of Soluble FMS­like Tyrosine Kinase­1 in Non-Pregnant and Pregnant Females: A Novel Biomarker for Pre-eclampsia.

OBJECTIVE: To determine the reference interval of soluble FMS-like tyrosine kinase-1 (sFIt-1) in healthy, non-pregnant and pregnant females. STUDY DESIGN: Observational study. Place and Duration of the Study: Department of Chemical Pathology, Chughtai Institute of Pathology, Lahore, from January to May 2023. METHODOLOGY: Blood samples were collected from 120 disease-free non-pregnant females of reproductive age group and 120 disease-free pregnant females with singleton fetuses from 15 to 28 weeks of gestational age. Healthy reference individuals were selected by correlating history with medical disorders like diabetes mellitus, hypertension, autoimmune diseases, inherited disorders, and by excluding any other drug history. All findings were recorded on health screening questionnaire. Levels of sFlt-1 were measured by a fully automated immunoassay analyser Cobas e601. Kolmogorov-Smirnov test was applied. The value of p <0.05 was considered significant. The 2.5th and 97.5th percentiles were computed at 90% CI by using the formula 0.025x (n+1) and 0.975x (n+1) which corresponded to rank number 1 and 7, respectively. The reference interval was calculated by the Rank-based method. RESULTS: Reference interval of sFlt-1 in non-pregnant and pregnant females were determined on the basis of 2.5th and 97.5th percentiles which were 57.7 to 118.5 pg/mL and 563.5 to 3288.0 pg/mL, respectively. CONCLUSION: The present study determined reference interval of sFlt-1 in healthy, non-pregnant and pregnant females in Lahore. KEY WORDS: Reference interval, Soluble FMS-like tyrosine kinase-1, Pre-eclampsia, Rank-based method.