Influence of renal function on spontaneous dietary intake and on nutritional status of chronic renal insufficiency patients.

OBJECTIVE: To analyze the spontaneous food intake and the nutritional parameters of patients with different degrees of chronic renal insufficiency (CRI) at the onset of predialysis treatment.
DESIGN: Cross-sectional.
SETTING: Outpatient Clinic of the Nephrology Division of Federal University of São Paulo, Brazil.
SUBJECTS: The analysis involved 487 (187 women and 300 men) patients with moderate to advanced CRI who were evaluated in the first visit to the clinic.
RESULTS: Patients were divided according to creatinine clearance (CrCl) quartiles. CrCl in the first quartile was lower than 19.9 ml/min/1.73 m(2) and in the fourth one was higher than 43 ml/min/1.73 m(2). Energy intake was significantly (P<0.05) lower in the first quartile when compared with the fourth one while protein intake estimated by protein equivalent of nitrogen appearance (PNA) was significantly lower in the first, second and third quartiles in comparison with the fourth (P<0.05). Body mass index (BMI) and percentage of ideal body weight were significantly decreased in the three lowest levels of renal function. Standard per cent of triceps skinfold thickness was lower in the first quartile when compared with the fourth one. Compared with the fourth quartile, standard per cent of midarm muscle circumference (MAMC) was lower in the second and in the third quartile. CrCl correlated directly and significantly with PNA (r=0.30; P<0.01), energy intake (r=0.17; P<0.01), and MAMC (r=0.20; P<0.01). In a multiple linear regression analysis, controlling for energy and protein intake, CrCl correlated significantly and positively with BMI and MAMC.
CONCLUSION: This study suggests that a spontaneous decrease in energy and protein intake as well as in anthropometric indices follows a decline in renal function in patients with no previous dietary intervention.