Impactos da dieta hipoproteica na função renal e no equilíbrio ácido-básico em pacientes com doença renal crônica

Abstract

Chronic Kidney Disease (CKD) is highly prevalent and represents a significant public health problem. It is characterized by structural or functional changes in the kidneys lasting three months or more, which can progress to metabolic acidosis, electrolyte disturbances, and disease progression. The main causes include diabetes mellitus and arterial hypertension. Metabolic acidosis is a frequent consequence of CKD, and diet plays a central role in modulating acid-base balance. This study aimed to evaluate the impacts of a low-protein diet on renal function and acid-base balance in Brazilian patients with CKD. This was a prospective, longitudinal, single-arm, uncontrolled clinical trial conducted with adult patients in stages G3a to G4 of CKD, followed for 12 months in a nephrology outpatient clinic. Patients clinically and cognitively able to follow dietary guidelines and who had not received prior nutritional treatment were included. Patients on dialysis, with comorbidities that could interfere with the results, changes in the medication regimen during the study, or lack of adherence to the dietary plan were excluded. The intervention consisted of prescribing a low-protein diet (0.6–0.8 g/kg/day), with quarterly nutritional monitoring, analysis of food intake, and calculation of dietary acid load using the Potential Renal Acid Load (PRAL) and Net Endogenous Acid Production (NEAP). Of the 59 patients recruited, 41 completed the study, 56% were male, and the mean age was 58 ± 24.2 years. Dietary adherence, assessed by dietary recall, was high (98%), with a mean protein intake of 0.68 ± 0.09 g/kg/day. A significant reduction in dietary acid load was observed (NEAP, p < 0.001; PRAL, p < 0.001). Regarding renal function, there was a decrease in urea (p = 0.041) and creatinine (p = 0.039), in addition to an increase in the estimated glomerular filtration rate (eGFR) (p = 0.030). There was also an increase in serum bicarbonate (p = 0.040) and improvement in potassium (p = 0.043) and phosphorus (p = 0.030) levels. The variation in sodium was not significant (p = 0.096). A positive correlation was identified between the increase in serum bicarbonate and the improvement in eGFR (r = 0.763; p < 0.001). It is concluded that the low-protein diet was effective in reducing dietary acid load, preventing metabolic acidosis, and improving renal function in patients with CKD.