Lupus nephritis: predictive value of conventional and Doppler US and comparison with serologic and biopsy parameters

To compare conventional and Doppler ultrasound (US) with clinical and biopsy parameters used to assess disease activity and outcome in lupus nephritis and to assess the predictive value of US.

Thirty-four patients with lupus nephritis prospectively underwent laboratory and US analysis at the time of renal biopsy. US parameters were renal length, relative echogenicity, and resistive index (RI). Laboratory parameters were serum creatinine level, urinary protein level, and serum markers of disease activity. Biopsy parameters were activity index, chronicity index, and assessment of the tubulointerstitium of the kidney. Follow-up data were obtained in all patients for at least 1 year.

Ten patients with elevated RI (>0.70) had significantly (P <.05) higher chronicity indexes and creatinine levels than the 24 patients with a more normal RI. RI correlated significantly (P <.05) with creatinine level, chronicity index, and presence of interstitial disease. Only RI and chronicity index were statistically significant predictors of a poor renal outcome. Abnormalities at conventional US were not predictive of renal outcome. A normal RI predicted a better renal outcome whether or not creatinine level was elevated.

Renal Doppler US may be of greatest clinical utility when its results are apparently discordant with renal functional assessment by allowing identification of patients with higher likelihood of subsequent improvement or worsening of renal status.