Renal Evaluation in Common Variable Immunodeficiency.

INTRODUCTION: Common variable immunodeficiency (CVID) comprises a heterogeneous group of disorders characterized by impaired antibody production. Kidney involvement in CVID is described in isolated and sporadic case reports. The objective of this study was to study the renal function pattern in CVID patients through glomerular and tubular function tests. METHODS: Study of 12 patients with CVID diagnosis and 12 healthy control individuals. Glomerular filtration rate (GFR), fractional excretion of sodium (FENa+ ) and potassium (FEK+ ), urinary concentration, and acidification capacity were measured. In addition, microalbuminuria and urinary monocyte chemoattractant protein-1 (MCP-1) were evaluated as markers of selectivity of the glomerular barrier and inflammation, respectively. RESULTS: In relation to glomerular markers, all CVID patients had normal GFR (>90 mL/min/1.73 m2), and microalbuminuria and urinary MCP-1 levels were also similar to those of controls. Interestingly, CVID patients had reduced urinary concentration capacity, as demonstrated by lower U/POsm ratio, when compared to controls. Also, while all control subjects achieved a urinary pH less than 5.3, no CVID patients showed a decrease in urinary pH to such levels in response to acid loading with CaCl2, characterizing impaired urinary acidification capacity. CONCLUSION: Patients showed a trend towards an elevated prevalence of tubular dysfunction, mainly related to urinary acidification and concentration capacities.

Quantitative Renal Echogenicity as a Tool for Diagnosis of Advanced Chronic Kidney Disease in Patients with Glomerulopathies and no Liver Disease.

BACKGROUND/AIMS: Glomerulopathy patients are prone to developing transitory reduced glomerular filtration rate (GFR), which can be difficult to differentiate from irreversible chronic kidney disease (CKD). Renal ultrasound can be useful, but differently from renal length, quantitative renal echogenicity has not been formerly evaluated regarding its capacity to identify irreversible advanced CKD. METHODS: A prospective study was performed, where quantitative renal echogenicity was performed during renal biopsy in patients with suspected glomerular disease (n=197). Quantitative echogenicity was measured as the inverse of the ratio between the mean pixel densities of the renal cortex and adjacent liver using ScionImage software. Patients were followed during a six-months period to ascertain irreversible advanced CKD. Quantitative renal echogenicity and histopathology parameters discriminatory capacity were compared regarding their capacity to detect advanced and irreversible CKD - estimated GFR less than 30mL/min/1.73m2 confirmed after a six-month follow-up. RESULTS: At renal biopsy, the mean eGFR was 53.9±33.6 mL/min/1.73m2 and 63 (32.0%) patients had an eGFR less than 30 mL/min/1.73m2. Mean kidney/liver echogenicity ratio was 1.06±0.19 and it was inversely correlated with eGFR at follow-up (r=-0.684, p<0.001). Multivariate analysis was performed to create a histopathology index that correctly identifies irreversible advanced CKD. Renal echogenicity discriminatory capacity to identify irreversible advanced CKD was 0.793 (0.719 -0.867), similar to the histopathology index. Elevated renal echogenicity with best discriminatory capacity was a kidney/liver ratio greater than 1.15. This cutoff had a predictive positive value of 92% in patients with eGFR less than 30mL/min/1.73m2. CONCLUSION: Quantitative renal echogenicity can be a useful tool in patients with glomerular disease and normal kidney size (>8cm) to identify those patients with irreversible advanced CKD.

Glycocalyx injury in adults with nephrotic syndrome: Association with endothelial function.

BACKGROUND: Glomerulopathy is a group of diseases that affect mainly young adults. Endothelial dysfunction, atherosclerosis, and increased cardiac mortality can complicate the evolution of such patients. However, there is no study evaluating endothelial glycocalyx in this pathology. METHODS: This cross-sectional study included 49 patients with untreated primary nephrotic syndrome that were otherwise healthy. In addition to routine laboratory measurements, syndecan-1, intercellular adhesion molecule-1 (ICAM-1), and e-selectin were measured. Moreover, flow-mediated dilation (FMD) was used as the main endothelial function surrogate. RESULTS: Of the 49 patients with nephrotic syndrome, 25 (51.0%) were females. The mean age of patients was 39.0±12.1y. FMD was reduced in nephrotic patients in comparison with controls (3.7±1.7 vs. 6.6±1.1%, p<0.001). Nephrotic patients had higher levels of ICAM-1 (616.6±219.7 vs. 356.9±102.0ng/ml, p<0.001) and syndecan-1 (180.3±64.1 vs. 28.2±9.8ng/ml, p<0.001). No significant difference was observed regarding e-selectin (129.9±54.2 vs. 120.2±61.5ng/ml, p=0.489). After adjusting for age and glomerular filtration rate, syndecan-1 was significantly associated with 24-h urinary protein excretion, LDL-cholesterol, HDL-cholesterol, and triglycerides. While age, LDL-cholesterol, and 24-h urinary protein excretion were associated with FMD in the multivariate analysis, when syndecan-1, ICAM-1, and e-selectin were added to the model, only syndecan-1 was independently associated with FMD. CONCLUSIONS: We demonstrated that syndecan-1, a marker of endothelial glycocalyx damage, is increased in patients with nephrotic syndrome and near-normal renal function. Moreover, we determined its association with nephrotic syndrome features and suggest it can have a role in the endothelial dysfunction of these patients.