Renal stones are reported to be one of the causes of hematuria in patients with juvenile rheumatoid arthritis (RA). We performed abdominal ultrasonography on patients with RA to investigate the frequency of renal stones and whether renal stones are related to hematuria.
We conducted abdominal ultrasonography in 224 patients with RA (42 men, 182 women). Mean age was 61.4 years, and the mean duration of disease was 13.5 years.
Renal stones were defined as hyperechoic spots with acoustic shadows, and they were observed in 37 patients. We also noticed hyperechoic spots without acoustic shadows in 50 patients. Five of these 50 patients also had renal stones. Twenty-one patients showing hyperechoic spots without acoustic shadows underwent computed tomographic scans, and apparent calcifications were observed in 10 patients. Age and sex matched controls had a significantly lower incidence of renal stones and hyperechoic spots without acoustic shadows than did patients with RA. Hematuria was more frequently observed in patients with RA with renal stones than in those without renal stones or hyperechoic spots without acoustic shadows. Urinary calcium/creatinine (Ca/Cr) ratios were elevated in patients compared to controls. Urinary Ca/Cr ratios in patients taking vitamin D3 were higher than those of patients not receiving the vitamin. Administration of vitamin D3 also was associated with increased incidence of renal stones.
We observed a high incidence of renal stones in patients with RA. Hematuria was more prevalent in patients with RA with renal stones than in those without. These results suggest the importance of performing abdominal ultrasonography on patients with RA.