Phosphate is associated with frailty in older patients with chronic kidney disease not on dialysis.

PURPOSE: Frailty is common in older patients with chronic kidney disease (CKD) and has been considered an independent risk factor for adverse clinical outcomes in this population. CKD-associated mineral and bone metabolism (CKD-MBD) increases energy expenditure and causes malnutrition and inflammation leading to frailty. We investigated whether CKD-MBD markers and energy metabolism are associated with frailty in patients with advanced CKD on conservative management. METHODS: In this cross-sectional study, we investigated factors associated with frailty in a sample of 75 patients ≥ 65 years, with stage 4 or 5 CKD. Collected data included age, sex, body mass index, physical activity status, educational level, Charlson Comorbidity Index, and laboratory markers. Frailty was evaluated according to Fried's classification. RESULTS: Frailty was observed in 51.3% and pre-frailty in 47.3%. The frail population was significantly older, with a high proportion of females, more inactive, had lower educational levels, spent a long time sitting throughout the day, and had higher phosphate and fibroblast growth factor 21 (FGF-21). In the multivariate logistic analysis age (odds ratio 1.13, p = 0.026) and phosphate (odds ratio 3.38, p = 0.021) remained independently associated with frailty. CONCLUSION: Serum phosphate seems to be a toxin associated with the frailty phenotype in older patients with CKD. Whether strategies to decrease serum phosphate would reduce the risk of frailty in this population deserves further evaluation.

Female Patient with Alport Syndrome and Concomitant Membranous Nephropathy: Susceptibility or Association of Two Diseases?

Alport syndrome (AS) is a disorder of collagen IV, a component of glomerular basement membrane (GBM). The association of AS and immunocomplex nephropathies is uncommon. This is a case of a 37-year-old woman with family history of X-linked AS, including 4 affected sons. This patient developed full-blown nephrotic syndrome along a 3-month period, a presentation not consistent with AS progression. This scenario suggested an alternative diagnosis. A kidney biopsy was therefore performed, showing membranous nephropathy (MN) in addition to GBM structural alterations compatible with AS. Whole exome sequencing also confirmed the diagnosis of X-linked AS, revealing a heterozygous pathogenic mutation in COL4A5. While a negative serum anti-phospholipase A2 receptor did not rule out a primary form of MN, it was also uncertain whether positive serologic tests for syphilis could represent a secondary factor. It is currently unknown whether this unusual association represents AS susceptibility to immunocomplex-mediated diseases or simply an association of 2 disorders.