Glomerular filtration rate variations in patients with solitary kidneys after a protein load.

The effects of an oral protein load, consisting of 1.5 g/kg body weight as cooked red meat, on: serum creatinine (SCr); glomerular filtration rate (GFR) ([125I]iothalamate clearance); and "renal functional reserve" (test-baseline GFR) (RFR) were evaluated in two groups of patients with solitary kidneys (SK). Group 1 had 7 patients with SCr of 1.00 to 1.40 mg/dl. Group 2 had 7 patients with SCr of 1.40 to 3.00 mg/dl. SCr and GFR were recorded during the 4 hours preceding and the 4 hours following the protein load. SCr rose significantly in both groups after protein load (from 1.16 to 1.19 mg/dl in Group 1, from 1.65 to 1.80 mg/dl in Group 2). GFR changes were: from 114.8 to 195.5 ml/min, from 59.0 to 107.7 ml/min, respectively in the two groups. The RFR was smaller in SK patients with early renal failure (ERF) (Group 2), 48.70 ml/min, than in those with normal renal function (Group 1), 80.77 ml/min. However, despite the smallest RFR, SK patients with ERF had the highest percentage increase in their GFR. In conclusion, in SK patients a hemodynamic adaptation to protein intake is present at different levels of renal function, and further studies are necessary to establish whether protein intake should be monitored in these patients.