[Relative renal function based on DMSA uptake corrected for volume: normalized relative renal function]

Relative renal function (RRF) quantification based on dimercaptosuccinic acid (DMSA) uptake is an established method for determining differential renal function. An abnormal kidney size may lead to an alteration in its RRF value, although it has no dysfunction. Therefore, it is useful to correct RRF values taking into account relative renal volumes, thus obtaining the normalized relative renal function (NRRF). The feasibility of the method used for volume correction, differences with respect to usual quantification and different normality intervals were studied.

A total of 187 DMSA renal scintigraphies (130 children and 57 adults) were studied. RRF was quantified and volume corrected to obtain NRRF. Patients were classified as normal or pathological using various normality intervals for NRRF. A second classification was performed depending on how the diagnostic changed after volume correction.

An increase of pathological diagnosis was observed after volume correction, mainly in children. Using an intermediate estimation for the normality interval, 53% of the initially pathological diagnosis for children may be caused simply by different renal volumes.

NRRF provides complementary information to RRF and helps to distinguish between a smaller kidney and a really hypofunctioning one in cases with abnormal RRF.