Prevalence of Proteinuria and Other Abnormalities in Urinalysis Performed in the Urology Clinic

Abstract

To compare the prevalence of proteinuria in the urology clinic with other outpatient settings. Chronic kidney disease is classified according to cause, glomerular filtration rate, and proteinuria. Proteinuria may be more prevalent in patients with known chronic kidney disease, renal disorders (benign or malignant), or after urologic surgery. A cross-sectional study of 3 populations undergoing urinalysis (UA) testing was carried out: general outpatients (n = 20,334), urology outpatients (n = 5023), and kidney cancer patients (n = 1016). Proteinuria was classified under Kidney Disease: Improving Global Outcomes guidelines: A1 (<30 mg), A2 (30-300 mg), and A3 (>300 mg). Proteinuria was detected throughout a community-based health system in 8.6% of UA (8.2%: A2; 0.4%: A3). In comparison, 18.6% of urology office-performed UA had proteinuria (16.0%: A2, 2.5%: A3) (P < .0001 vs non-urology). Kidney cancer patients were more likely to have proteinuria (17.9%: A2, 3.8%: A3). The proportion with A3 was significantly higher in urology and kidney cancer patients when compared with other outpatients (each P < .0001), and in the kidney cancer subgroup compared with all urology patients (P < .0001). Additional abnormalities were frequently present on microscopic analysis of UA in the urology clinic, including hematuria (20.9%), pyuria (21.8%), and bacteriuria (3.1%). The value of UA in the urology clinic as a screening test for proteinuria and other conditions appears high, with >56% having at least 1 abnormality. The population risk of proteinuria in the urology clinic is 18.5%, which is higher than that observed in non-urology clinics. Patients with kidney cancer appear more likely to have proteinuria than the average urology patient. We recommend evaluation of urology patients with UA to identify proteinuria.