Reliability of different equation for estimating glomerular filtration rate in the classification stage of endemic nephropathy

Otkrivanje kronične bubrežne bolesti (KBB) u ranoj fazi može spriječiti ili usporiti napredovanje bolesti i smanjiti rizik komplikacija. Stadiji KBB se prema klasifikaciji National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF K/DOQI) određuju na temelju procjene brzine glomerularne filtracije (engl. Glomerular Filtration Rate, GFR) koja se izračunava pomoću prediktivnih jednadžbi baziranim na vrijednosti kreatinina u serumu i drugih varijabli kao što su dob, spol, rasa i tjelesna masa. U ovom radu ispitana je pouzdanost prediktivnih jednadžbi (CG-Cockcroft - Gault, MDRD2-Modification of Diet in Renal Disease Study, MCQE-Mayo clinic quadratic equation i CKD-EPI-Chronic Kidney Disease Epidemiology Collaboration) za procjenu učestalosti pojedinih stadija KBB u područjima s endemskom nefropatijom (EN). Također, ispitano je koreliraju li vrijednosti transformirajućeg čimbenika rasta β (engl. Transforming Growth Factor-β, TGFβ) u uzorcima mokraće ispitanika s KBB, tj GFR određenoj različitim jednadžbama što predstavlja novi doprinos spoznavanju patofiziologije endemske nefropatije. Dobiveni rezultati pokazuju vrlo visoku prevalenciju KBB u ruralnom hrvatskom području te razliku u svrstavanju ispitanika u stadije bubrežnog oštećenja 3-5 ovisno o primjenjenoj jednadžbi. Najlošiju podudarnost s ostale tri jednadžbe imala je CG jednadžba, dok su najbolju usporedbu pokazale jednadžbe MDRD2 i CKD-EPI. Zbog dokazane značajne povezanosti procijenjene GFR i dijagnoze EN, dobiveni rezulatati upućuju na mogućnost jasnog razlikovanja pojednih podskupina ispitanika u EN selima pa procjena GFR prediktivnim jednadžbama treba biti i dalje uključena u kriterije za EN. TGFß kao biljeg uznapredovale fibroze, nije se pokazao kao pouzdan biljeg u razlikovanju podskupina bolesnih i ostalih ispitanika. Detection of the Chronic kidney disease (CKD) disease in an early stage can help prevent or slow the progression of CKD and reduce the risk of complications. CKD stages, according to the classification NKFK /DOQI, are classified based on the estimated glomerular filtration rate (GFR) calculated using predictive equations. This study analyze how different predictive equations (CG – Cockcroft -Gault, MDRD2 - Modification of DietinRenal DiseaseStudy, MCQE - Mayo Clinic Quadratic equation and CKD-EPI - Chronic Kidney Disease Epidemiology Collaboration) have an influence on assessing CKD in Croatia endemic nephropathy (EN) region. A total of 1573 inhabitants of the Croatian Posavina rural area from 6 endemic and 3 non-endemic villages were enrolled. Participants were classified according to the modified criteria of the World Health Organization for EN. The aim was to examine the effect of different GFR equations on GFR and to determine prevalence of CKD stages 3-5 in Croatian endemic region. Also, it was analyzed are the TGFß values in patients urine samples correlated with estimated GFR calculated using different predictive equations. The results show a very high CKD prevalence and differences in the classification of patients in stages 3-5. The CG equation demonstrated worst concordance with other studied equations, while MDRD2 and CKD-EPI showed the best compatibility. TGFß has not proved to be a reliable marker in distinguishing between a subset of the sick and other of subjects. Estimated GFR correlated significantly with the diagnosis of EN. Kidney function assessment using predictive equations proved to be a good marker in differentiating the study subgroups remined as one of the diagnostic criteria for EN.