Protein intake in renal disease

• Published in: Journal of the American Society of Nephrology 1997-05, Vol.8 (5), p.777-783
• Main Authors: POLLOCK, C. A, IBELS, L. S, ZHU, F.-Y, WARNANT, M, CATERSON, R. J, WAUGH, D. A, MAHONY, J. F
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Biological and medical sciences; Child; Counseling; Diet; Dietary Proteins - administration & dosage; Female; Glomerulonephritis; Glomerulonephritis - diet therapy; Glomerulonephritis - physiopathology; Glomerulonephritis - urine; Humans; Kidney Diseases - diet therapy; Kidney Diseases - physiopathology; Kidney Diseases - urine; Male; Medical sciences; Middle Aged; Nephrology. Urinary tract diseases; Nephropathies. Renovascular diseases. Renal failure; Peritoneal Dialysis, Continuous Ambulatory; Proteinuria - urine; Renal Dialysis
• ISSN: 1046-6673; 1533-3450
• DOI: 10.1681/asn.v85777

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 th