title: Protein intake in renal disease.
abstract: The dietary protein intake (DPI) of 766 patients (aged 7 to 88 yr) was determined from 24-h urinary urea and protein excretion by urea kinetic modelling. Five hundred sixty-five patients had a normal serum creatinine concentration, and of these 565, 385 patients had no dietary modification advised and 180 were advised to follow a low-protein diet. The remaining 201 patients had an increased serum creatinine concentration; 148 of these 201 patients had been advised to restrict their DPI. Patients with a normal serum creatinine concentration who had no dietary restriction had a significantly higher DPI than those advised to restrict their protein intake (1.08 +/- 0.01 versus 0.96 +/- 0.02 g/kg per day (mean +/- SEM), P < 0.01). Similarly, patients with abnormal renal function who were advised to follow a low-protein diet had a reduced DPI (0.93 +/- 0.01 versus 0.87 +/- 0.02 g/kg per day; P < 0.05). A lower DPI correlated with level of renal dysfunction, independent of dietary advice (P < 0.0001). In the overall population, DPI correlated with body mass index (BMI; P < 0.0001) and serum albumin (P < 0.0001), and inverse correlations were evident between age (P < 0.0001), blood glucose level (P < 0.01), serum cholesterol level (P < 0.0001), and triglyceride levels (P < 0.0001) independently of renal function. Fifty-two patients were assessed within the 3 months before the commencement of dialysis, and 47 were reassessed within 3 months after the commencement of dialysis. Despite advice regarding an increase in dietary protein after the commencement of dialysis, this increase failed to occur within the 3 months of commencement of dialytic therapy (0.79 +/- 0.04 versus 0.82 +/- 0.03 g/kg per day); P = 0.64). However, 6 to 9 months after the commencement of dialysis, a significant increase in protein intake was evident (1.04 +/- 0.04 g/kg per day; P < 0.005 versus both prior measurements). Hence a low DPI in renal impairment occurs independently of dietary advice, but compliance with such advice is evident because patients advised to consume a low-protein diet had significantly lower protein intake than did patients receiving no dietary advice. Adaptation to a high-protein diet after instigation of dialysis is unsuccessful in the short term, irrespective of whether or not advice is given regarding a low-protein diet before dialysis is initiated. However, 6 to 9 months after the commencement of dialysis, a significant increase in protein intake occurs, which in the hemodialysis population correlates with dialysis delivery.
authors.affiliation: Department of Renal Medicine, Royal North Shore Hospital, New South Wales, Australia.
authors.forename: C A
authors.initials: CA
authors.lastname: Pollock
authors.forename: L S
authors.initials: LS
authors.lastname: Ibels
authors.forename: F Y
authors.initials: FY
authors.lastname: Zhu
authors.forename: M
authors.initials: M
authors.lastname: Warnant
authors.forename: R J
authors.initials: RJ
authors.lastname: Caterson
authors.forename: D A
authors.initials: DA
authors.lastname: Waugh
authors.forename: J F
authors.initials: JF
authors.lastname: Mahony
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D003376:Counseling; D004032:Diet; D004044:Dietary Proteins / Q000008:administration & dosage*; D005260:Female; D005921:Glomerulonephritis / Q000178:diet therapy / Q000503:physiopathology / Q000652:urine; D006801:Humans; D007674:Kidney Diseases / Q000178:diet therapy* / Q000503:physiopathology* / Q000652:urine; D008297:Male; D008875:Middle Aged; D010531:Peritoneal Dialysis, Continuous Ambulatory; D011507:Proteinuria / Q000652:urine; D006435:Renal Dialysis
chemical_list: D004044:Dietary Proteins