HDCN Article Review/Hyperlink

Nomura S, Watanabe Y, Otsuka N, Osawa G

Gallium 67 scintigraphy as a predictor of renal prognosis in primary IgA nephropathy

Am J Kidney Dis (Feb) 27:204-208 1996

Nomura et al performed renal gallium 67 scintigraphy using gallium 67 citrate and technetium 99 dimercaptosuccinate (DMSA) in Japanese IgA nephropathy patients. They determined the radioisotope uptake ratio between the left kidney and soft tissue adjacent to the third and fourth lumbar vertebrae (L/S ratio) and compared these ratios in patients with serum creatinine levels less than 2.0 mg/dl. Analyzed were the 24 hour urine protein excretion, serum immunoglobulin values and qualitative histologic grading of the renal biopsies. Renal follow-up was based on the slope of the reciprocals of the serum creatinine values over time.

The authors showed a negative correlation between the degree of radioisotope uptake ratio and the slope of the reciprocal serum creatinine in 20 patients. They also showed a statistically significant decrease in life table analysis of renal survival in patients with an L/S ratio greater than the overall mean. They therefore concluded that renal gallium 67 scintigraphy is predictive of renal prognosis in IgA nephropathy.

Comment: The authors found that patients with heavy proteinuria tended (though not to a statistically significant level) to have high L/S ratios, raising the question as to whether or not renal gallium uptake provided any increased information not available from analysis of the urinary protein excretion alone. The authors also could not demonstrate a statistically significant correlation between L/S ratio and the degree of interstitial changes on renal biopsy. In summary, the study shows that patients with IgA nephropathy who have high renal gallium uptake are more likely to be those with increased proteinuria, an indicator that is already known to correlate with a poor renal prognosis in IgA disease. Until further studies are performed, gallium scintigraphy can not be recommended as a definitive method of predicting renal prognosis in patients with IgA nephropathy. (N. Kevin Krane, M.D., Tulane University)