ISOLATED MICROSCOPIC HEMATURIA IN PATIENTS WITH RHEUMATOID-ARTHRITIS COMPARED WITH AGE AND SEX MATCHED CONTROLS - A POPULATION-BASED STUDY

Objective. To evaluate the prevalence and causes of isolated microscop ic hematuria in patients with rheumatoid arthritis (RA). Methods, An u nselected population of 1018 patients with RA (810 women, 208 men) wer e studied prospectively (n = 604) or retrospectively (n = 414), and th e results were compared with an age and sex matched control population (n = 457; 352 women, 105 men). Hematuria was defined as a positive di pstick result in 2 urine samples, and was regarded as isolated when no concomitant proteinuria was found (urine protein excretion less than or equal to 0.15 g/24 h). To investigate the urological causes of isol ated hematuria,urine cytology, renal ultrasound, and urethrocystoscopy were undertaken. Renal biopsy was performed when no urological lesion s were found. Results, There was no difference in the prevalence of is olated hematuria between patients with RA and controls (women 10 and 9 %, men 5 and 6%, respectively; total 9% for both). Mild mesangial glom erulopathy was the most common renal biopsy finding in patients with R A with isolated hematuria, found in 13 of 15 adequate renal biopsy spe cimens. The cause of hematuria remained uncertain or unknown in 52% of the patients with RA and in 61% of controls. Conclusion, The prevalen ce of isolated microscopic hematuria was not significantly more freque nt in patients with RA than in age and sex matched controls. This resu lt was independent of the definition or grade of hematuria. Mesangial glomerulopathy was the most common renal biopsy finding in patients wi th RA with isolated hematuria.