Proteinuria and its relation to diverse biomarkers and body mass index in chronic hemodialysis

N-Terminal Pro-Brain Natriuretic Peptide Correlates with Ghrelin and Acyl-Ghrelin in Pre-Dialysis Chronic Kidney Disease

Pro-B amino-terminal natriuretic peptide (NT-proBNP) is a diagnostic marker for heart failure (HF), a severe complication of chronic kidney disease (CKD). However, its significance in CKD is not clear, as other factors, such as renal function, may also have an impact. Recent studies have shown that ghrelin treatment is effective in HF in the general population, but the impact of ghrelin on cardiac function in CKD patients is still unknown. Our study aimed to investigate the factors associated with NT-proBNP in pre-dialysis CKD patients and to evaluate the correlation between NT-proBNP and ghrelin and acyl-ghrelin, molecules determined using ELISA methods. In a cross-sectional observational study, we included 80 patients with pre-dialysis CKD, with a mean age of 68 years and 50% men. The median values for NT-proBNP were 351.8 pg/mL, for acyl ghrelin 16.39 pg/mL, and for ghrelin 543.32 pg/mL. NT-proBNP was correlated with ghrelin (p = 0.034, r = 0.24), acyl-ghrelin (p = 0.033, r = -0.24), estimated glomerular filtration rate (p = 0.027, r = -0.25), serum urea (p = 0.006, r = 0.31), and ferritin (p = 0.041, r = 0.28). In multivariate analysis, ghrelin (p = 0.040) and blood urea (p = 0.040) remained significant predictors for NT-proBNP levels. NT-proBNP was a significant predictor for acyl-ghrelin (p = 0.036). In conclusion, in pre-dialysis CKD patients, a high value of NT-proBNP was associated with a high value of total ghrelin and a low value of acyl-ghrelin.

Ghrelin and acyl ghrelin levels are associated with inflammatory and nutritional markers and with cardiac and vascular dysfunction parameters in hemodialysis patients

PURPOSE

Exogenous ghrelin is associated with cardiovascular protection in experimental and human studies. Nevertheless ESRD patients have increased ghrelin levels and severe cardiovascular comorbidities. This study aims to elucidate the metabolic factors influencing endogenous ghrelin/acyl ghrelin levels and to analyze the relation between endogenous ghrelin/acyl ghrelin levels and cardiac and vascular function markers in hemodialysis patients.

METHODS

The cross-sectional study was conducted in hemodialysis patients (n = 88); 50 of them were men, mean age 61.1 ± 13.5 years, 17% had diabetes. We assessed nutritional and inflammatory status and analyzed the determinants of ghrelin/acyl ghrelin and their relation with cardiac and vascular function.

RESULTS

Ghrelin is correlated with IL-1β (r = 0.88, p < 0.0001), triglycerides, total cholesterol (TC), and Kt/V. IL-1β is the strongest predictor of ghrelin levels (p < 0.0001). Acyl ghrelin is correlated with TC (r = 0.36, p = 0.001), LDL-cholesterol, serum bicarbonate, body mass index. TC is the strongest predictor for acyl ghrelin levels (p = 0.038). Patients with high ghrelin levels had significantly decreased nitroglycerin-mediated dilation (p = 0.05) and higher IL-1β levels (p < 0.001); increased NT-proBNP is associated with lower levels of acyl ghrelin (r = - 0.33, p = 0.02) in male patients.

CONCLUSION

The inflammatory marker IL-1β is in our study the strongest predictor of ghrelin levels while the nutritional marker-total cholesterol is the strongest predictor for acyl ghrelin levels in HD patients. High endogenous ghrelin level is associated with high IL-1β and with vascular smooth muscle cell dysfunction. Low acyl ghrelin level is associated with high NT-proBNP (a cardiac dysfunction marker) in male HD patients. There is a direct correlation between endogenous ghrelin level and inflammatory markers, which is not related with cardiovascular protection.

Podocyturia: What is in a name?

The podocyte is a highly differentiated cell located in the outer space of the glomerular basement membrane that deals with many different functions. This phylogenetically preserved cell that is responsible for the virtually absence of proteins in the urine lacks of the capacity to divide under normal conditions. When podocytes receive molecular insults, which normally occur during stress conditions as glomerulonephritis, hyperfiltration or metabolic disturbances, they adapt to the new situation by contracting their actin fibers. This adaptive behavior puts at risk the quality of the plasmatic filtration due to the denudation of the glomerular basement membrane, the potential mesangial inflammation and the appearance of proteinuria; podocytes run the risk of detachment from the basement membrane due to a decrease in the adherence to the surrounding matrix after contraction, a process called foot processes effacement. Podocytes change their shape and under constant mechanical stress they finally detach, rendering the glomerular basement membrane unprotected unless other contiguous podocytes are capable of covering the surface. However, these still anchored podocytes are generally also under the same stress situation and follow the same pathway. Podocyturia refers to the presence of these differentiated cells in the urinary sediment. Noteworthy, the podocytes that are encountered in the urine are viable despite the glomerular hostile environment and the urinary acidity. Podocyturia can precede proteinuria and can aggravate it. Therefore, in diseases that can threaten the glomerular normal environment, the presence and the quantification of urinary podocytes can be of remarkable relevance, as it can herald or accompany the appearance of proteinuria, and could offer another view to the interpretation and clinical approach and outcome of proteinuria. However, its identification needs a wide-spread training among biochemists and technicians, as well as commercially available kits.

Residual urinary output in high body mass index individuals on chronic hemodialysis: A disregarded life vest?

AIM: To assess residual diuresis and diverse variables according to body mass index (BMI).

METHODS: Cross-sectional study (n = 57), with 3 groups. Group A: BMI < 25, n = 22; Group B: BMI 25-30, n = 15; Group C: BMI > 30, n = 20. Diuresis, hematocrit, albumin, C-reactive protein, Malnutrition inflammatory score, Pro-BNP, Troponin T, leptin and insulin levels are expressed as median and ranges (r).

RESULTS: Albumin (g/dL): GA vs GC, 3.70 (r2.20-4.90) vs 3.85 (r3.40-4.90), P = 0.02. Diuresis (mL/d): GA 690 (r0-1780); GB 660 (r60-1800); GC 840 (r40-2840). Diuresis GA vs GC, P = 0.01. Leptin (ng/mL): GA vs GC, 3.81 (r0.78-69.60) vs GC, 32.80 (r0.78-124.50), P < 0.001. Insulin (µU/mL): GA vs GB, 7 (r2-44) vs 11.50 (r4-38), P = 0.02; GA vs GC, 7 (r2-44) vs 19.5 (r5-155), P = 0.0001. Troponin T and Pro-BNP levels were not different. Significant correlations: GC, Insulin-UF: ρ = 0.53; P = 0.03; TroponinT-diuresis: ρ = -0.48, P < 0.05; Pro-BNP-diuresis: ρ = -0.39, P < 0.01; Troponin T-ProBNP: ρ = 0.77, P < 0.0001; albumin-Troponin T: ρ = -0.66, P < 0.0001; albumin-ProBNP: ρ = -0.44, P < 0.05.

CONCLUSION: High BMI associated positively with higher diuresis and albuminemia, and negatively with TropT and Pro-BNP. High BMI-associated better survival may be explained by better urinary output, lowering cardiovascular stress.