Avaliação do conhecimento e da ingestão de proteína, fósforo e sódio em pacientes com doença renal crônica na fase não dialítica: associação com o distúrbio do metabolismo mineral ósseo

Abstract

Introduction: The restriction of protein, phosphorus and sodium in the diet contributes to better clinical and nutritional profile in chronic kidney disease (CKD), favoring bone mineral metabolism (BMM) control. Low adherence to diet is related to socioeconomic-demographic characteristics. Some studies evaluated protein, phosphorus and sodium intake in CKD patients. However, the knowledge profile of these nutrients food sources and their intake in association with BMM parameters has not been described. Objectives: To evaluate the knowledge of food sources and the intake of protein, phosphorus and sodium in non-dialysis dependent CKD patients, and to analyze the associations with BMM parameters. Methods: A cross-sectional observational study was conducted with patients under multidisciplinary treatment at CKD clinic at the Pedro Ernesto University Hospital (HUPE). The knowledge of protein, sodium and phosphorus food sources was assessed by a questionnaire previously used in other studies conducted at this clinic. The food intake was evaluated by 3-day food record (FR3d), by 24-hour urine analysis (Ur24h), and nutritional assessment by anthropometry. The routine laboratorial parameters, as well as parathyroid hormone (PTH) and vitamin D were analyzed at HUPE laboratory. Fibroblast growth factor-23 (FGF23) was analyzed by ELISA with a commercial kit. Glomerular filtration rate was estimated (eGFR) by the CKD-EPI equation. Results: A total of 140 CKD patients (63 males, 45%), with 64.5±12.0 years and eGFR=25.5±11.4 ml/min. were evaluated. The majority presented the following profile: 81.4% were the owners of their house, 54.3% living with a partner, 60.7% elementary school and 58.6% presented familiar income <1 minimum salary/month. Overweight/obesity was the prevalent nutritional condition (62.1%, n=87). The knowledge (%correct answers) of sodium sources was higher compared to protein and phosphorus (79.7±13.9 vs. 62.5±21.4% and 47,6±25,5%, respectively. Patients with higher knowledge of protein sources (> 70% correct answers) presented higher eGFR and lower uric acid. Low energy and lipids intake by FR3d revealed underreporting. Ur24h analysis revealed high intake of protein (1.01±0.49 g/kg body weight/d) and sodium (3245±2026 mg/d), and low phosphorus intake (424 mg/d; 324-859). The protein intake was positively correlated with sodium and phosphorus intake (p <0.05). Frequency of Hyperparathyroidism (HyPT: PTH &#8805; 65 ng/dl), vitamin D insufficiency ([25(OH)D]: <30 ng/dl) and hyperphosphatemia (HPhos &#8805;4.5 mg/dl) were 71.3%, 35.4% and 14.7%, respectively. Bone Mineral Metabolism Disorder (BMMD) was determined by the presence of at least 2 out of these 3 conditions, with a frequency of 33.1%. Patients with BMMD had lower eGFR and hemoglobin, and higher FGF23 (with: BMMD: 53.0±19.4 pg/ml vs. without BMMD: 65.0±24.4 pg/ml; p=0.03). BMMD was associated with higher protein intake (&#8805;1.3 g/kg body weight/day), independent of age, sex, eGFR and anthropometry. Conclusions: The present study evidences low knowledge of patients with CKD about food sources of protein and phosphorus, and high about sodium sources. The intake of protein and sodium is high, while phosphorus intake is low. High protein intake was associated with BMMD.