Protein energy-wasting associated with nephrotic syndrome – the comparison of metabolic pattern in severe nephrosis to different stages of chronic kidney disease

BACKGROUND: Nephrotic syndrome (NS) is associated with a hypercatabolic state expressed as an exacerbated degradation of muscle mass. However, the clinical significance of this phenomenon has not yet been investigated. The aim of the study was to evaluate the nutritional status of patients with severe NS (defined as nephrotic range proteinuria with hypoalbuminemia ≤2.5 g/dL) and estimated glomerular filtration rate (eGFR) ≥45 mL/min/1.73 m(2) in comparison to patients in different stages of chronic kidney disease (CKD). METHODS: Twenty men with severe NS (NS group) and 40 men without proteinuria similar in term of serum creatinine (control group) were included into the study. A retrospective cohort of 40 men with CKD stage G4 (PreD group) and 20 haemodialysis men (HD group) were added to the analysis after matching for age, height and weight using propensity score matching. The bioimpedance spectroscopy and biochemical nutritional markers were evaluated. RESULTS: Nephrotic patients had a significantly lower lean tissue mass (LTM; p = 0.035) and index (a quotient of LTM over height squared, LTI; p = 0.068), with an expected deficiency of LTM by 3.2 kg, and LTI by 0.9 kg/m(2) when compared to the control group. A significant lean tissue deficit (defined as LTI below the lower limit of the reference range by 1.0 kg/m(2)) was observed in 12.5% of patients in the control group in comparison to 31.7% with advanced CKD (PreD+HD; p = 0.032) and 50% with NS (p = 0.003). NS group presented with higher phosphorus (p = 0.029), uric acid (p = 0.002) and blood urea (p = 0.049) than the control group. Blood urea was strongly negatively correlated with LTM in NS (r = − 0.64, p = 0.002). Nine nephrotic patients (45%) were identified as hypercatabolic based on severe hyperphosphatemia (> 5.0 mg/dL) and/or hyperuricemia (> 8.0 mg/dL), and were characterized by higher blood urea and lower prealbumin, as well as LTM lower by 5.6 kg than in less catabolic individuals. CONCLUSIONS: In term of lean tissue amount, NS group was more similar to advanced CKD than to the control group. We concluded that specific metabolic pattern with elevated phosphorus, uric acid and blood urea, and lean tissue deficiency may be defined as protein-energy wasting associated with nephrotic syndrome (neph-PEW).