Gallium-67 scintigraphy to predict response to therapy in active lupus nephritis

Gallium-67-citrate has been used to detect inflammation for decades, and 67Ga uptake usually indicates an active, potentially curable lesion. In this study, we determined the value of 67Ga renal scintigraphy for predicting response to therapy in patients with lupus nephritis.

Forty-seven patients with lupus nephritis and abnormal serum creatinine or elevated 24-hr urine protein were enrolled. Delayed 48-hr 67Ga imaging was performed to evaluate 67Ga uptake by the kidneys. Serum creatinine and 24-hr urine protein values were obtained at the beginning of this study and after 1 yr of treatment. Serum creatinine was considered abnormal at levels greater than or equal to 1.4 mg/dl and 24-hr urine protein at levels greater than or equal to 1.0 g/day. When the value of serum creatinine or 24-hr urine protein obtained 1 yr after treatment was in the normal range or was 50% of the initial abnormal value, the patient was considered to have good response to treatment.

Gallium-67 renal scan showed good correlation with the response to therapy in patients with lupus nephritis. In the negative 67Ga scan group, no significant changes in laboratory data were noted between onset of this study and after 1 yr of therapy. In the positive 67Ga scan group, there were significant decreases in serum creatinine and 24-hr urine protein levels 1 yr after treatment, especially in 24-hr urine protein, with p values of 0.019 and 0.0007 respectively, by Student's t-test for dependent samples. Moreover, 11.5% of patients with a negative 67Ga scan had a good response to treatment, whereas 71.4% of patients with a positive 67Ga scan had a good response to treatment.

We suggest that 67Ga renal scan is a valuable predictor of response to therapy in patients with lupus nephritis.