AB0572 Correlation of 24 hours urinary proteinquantification with random spot urine protein/creatinine ratio in patients with active lupus nephritis
Authors: F. Elbadawi, M. Khamashta, J. Alsaleh
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Proteinuria is an important signal of Lupus nephritis. The standard method of proteinuria quantification is 24 hours urine collection. The ongoing practice of using spot urine sample to determine the ratio between protein and creatinine excretion as a convenient, alternative method of proteinuria estimation is not without limitation and criticism questioning its accuracy. <h3>Objectives</h3> Given the cumbersome expressed by some patients on collecting 24 hours urine for protein quantification, our aim was to determine the correlation between spot urine protein-to-creatinine ratio (PCR) and 24 hour urinary protein (UP) in patients with active Lupus nephritis. <h3>Methods</h3> The active patients included in the analysis was 53 attending Dubai Hospital shared Rheumatology/Nephrology clinic during the period of June 2016 till Dec 2017. All diagnosed to have systemic lupus erythematosus who either had flare with proteinuria or newly diagnosed as Lupus nephritis,. Suspicion of active Lupus nephritis was evidenced by active urine sediment and 24 hours UP quantification of more than 0.5 gm or more than 1.0 gm regardless to urine sediment. Paired baseline urine samples were obtained and results included in the final analysis. Most of the patients underwent ultrasound guided kidney biopsy to classify the nephritis according to ISN/RPS 2003 classification, unless contra-indicated or patient refused to give consent. We used Minitab 18.1 software to determine the Spearman's correlation coefficient (r), and it is significance. P- Value &lt;0.05 was considered statistically significant <h3>Results</h3> Total of 54 patients evaluated, one patient excluded from the analysis as the patient nephritis was not related to lupus. 93% of the patients were females (49/53) while 7% were males (4/53). 42 patients underwent ultrasound guided kidney biopsy (79%) while 21% of the patients the histopathology class was not defined as no biopsy obtained either due to contra-indication to the procedure (i.e.: single kidney, flared during pregnancy) or the patient refusal to go for biopsy. 15 patients out of 53 (28%) had nephrotic range proteinuria (defined as urinary proteinuria level of more than 3.5 gm per 24 hours), on the other hand 72% (38/53) had sub nephrotic range. Linear regression Analysis revealed positive correlation between the two methods of estimation mainly at lower levels of proteinuria (less than 3.5 gm). We found a positive correlation between PCR and 24 hours UP quantification. The overall corrected correlation coefficient was r=0.46, with P value&lt;0.0001. <h3>Conclusions</h3> PCR in spot urine specimens is an accurate and convenient method to estimate the protein excretion in urine only when proteinuria is at sub nephrotic range. Prospective study is required to explore the effect of disease activity, disease duration and co-morbidities on the correlation and predictive power of the model. <h3>References</h3> [1] G K Bertsias, Joint European League Against Rheumatism and European Renal Association–European Dialysis and Transplant Association (EULAR/ERA-EDTA) recommendations for the management of adult and paediatric lupus nephritis, Ann Rheum Dis. 2012;71(11):1771–1782. [2] JAN J. WEENING, The Classification of Glomerulonephritis in Systemic Lupus Erythematosus Revisited, J Am Soc Nephrol2004;15:241–250 <h3>Disclosure of Interest</h3> None declared