Cross-sectional evaluation of kidney function in hospitalized patients: estimated GFR versus renal scintigraphy

Accurate staging of chronic kidney disease (CKD) is very important. We tried to identify difference in GFR evaluation between CKD-EPI and Gates method with renal scintigraphy and which variables are associated with these differences.

We retrospectively reviewed the records of 341 patients who underwent dynamic renal scintigraphy in the last 5 years. Patients were categorized according to KDIGO staging I to V, using the eGFR calculated with the CKD-EPI equation. Secondarily, we stratified patients according to treatment with renin-angiotensin system (RAS) inhibitors.

Gates method tends to underestimate GFR especially in CKD stage I (mean -22.2 ml/min) and II (mean -12.5 ml/min). The division in quartiles of ages showed an underestimation of GFR only in the first quartile of age (< 50 years old). Gates method underestimation of GFR was more pronounced in stage I patients treated with RAS inhibitors (mean -34.6 ml/min). The same occurs in stage II, even though to a lesser extent.

The assessment of GFR by the Gates method must be carefully considered in the early stages of CKD, especially in younger patients. Moreover, the difference is more pronounced in patients treated with RAS inhibitors. Longitudinal studies will prove which method better predicts cardiovascular or renal events.