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)