Pretherapeutic estimation of kidney function in patients treated with peptide receptor radionuclide therapy: Comparison of renal scintigraphy, venous blood sample and urine collection

Objectives Pretherapeutic assessment of kidney function before PRRT is important. The practical guidance on PRRT does not give an explicit recommendation which method estimating kidney function should be used (1). The aim of this study was to investigate the correlation between Tc99-MAG3 clearance, GFR of venous blood samples and urine-based creatinine clearance in patients treated with PRRT.

Methods 29 consecutive patients treated with PRRT were enrolled (mean: after 3 cycles). Prior to therapy, renal function was assessed by 24h urine collection, Tc99-MAG3 renal scintigraphy and venous blood samples. PRRT with standard activities (7,5 GBq ± 432 MBq of 177Lu-DOTATATE) was administered. Tc99-MAG3 clearance was compared with urine-based creatinine clearance/ GFR of venous blood sample.

Results All patients had a normal kidney function according to Tc99-MAG3 scintigraphy, 24h-urine collection and venous blood sample. The mean urine-based creatinine clearance (110 ± 39 mL/min/1.73 m2) correlated significantly with Tc99-MAG3 clearance (222 ± 48 mL/min/1.73 m2) (r=0.579, p=0.002). The mean GFR of venous blood sample (86 ± 26 ml/min) correlated significantly with Tc99-MAG3 clearance (222 ± 48 mL/min/1.73 m2) (r=0.547, p=0.002).

Conclusions Our study suggests that the Tc99-MAG3 and urine-based creatinine clearances of patients undergoing PRRT are highly correlated (r=0.579) as well as Tc99-MAG3 clearance and GFR of venous blood sample (r=0.574). Nevertheless, renal scintigraphy seems to be still the gold standard and should be used before first treatment cycle, in all children and every compromised patient. In all other cases, estimation by urine collection or venous blood sample alone could be sufficient.