BACKGROUND: The occurrence of vascular stiffness in the setting of the nephrotic syndrome and the influence of serum phosphate on this association is unknown. METHODS: A retrospective study of 42 prevalent, adult nephrotic patients who underwent carotid-femoral pulse wave velocity (PWV) measurement, a median of 24 months after kidney biopsy. Elevated PWV was determined using published age-specific reference ranges. The association, statistical significance and independence of serum phosphate with spot urine protein-creatinine ratio (PCR) and the association of phosphate with PWV was examined. RESULTS: Mean PCR was 5.5 g/g and mean eGFR (CKD-EPI) was 70 mL/min/1.73 m2. Serum phosphate was statistically significantly associated with severity of nephrotic syndrome independently of eGFR and age. Median (intra-quartile range) PWV was 7 m/s (4-11), with a linear trend for higher PWV across tertile of average serum phosphate over follow-up, P<.001. Twenty subjects (48%) had elevated age-specific PWV, which on logistic regression was statistically significantly associated with mean serum phosphate, OR (95% CI) per 0.1 mmol/L: 2.7 (1.5, 4.9), P = .001, which in separate analyses was independent of eGFR and other laboratory data. CONCLUSIONS: In this cohort of patients with the nephrotic syndrome serum phosphate was commonly elevated, despite well preserved eGFR, which was significantly and independently associated with elevated PWV over follow-up.
BACKGROUND: The occurrence of vascular stiffness in the setting of the nephrotic syndrome and the influence of serum phosphate on this association is unknown. METHODS: A retrospective study of 42 prevalent, adult nephroticpatients who underwent carotid-femoral pulse wave velocity (PWV) measurement, a median of 24 months after kidney biopsy. Elevated PWV was determined using published age-specific reference ranges. The association, statistical significance and independence of serum phosphate with spot urine protein-creatinine ratio (PCR) and the association of phosphate with PWV was examined. RESULTS: Mean PCR was 5.5 g/g and mean eGFR (CKD-EPI) was 70 mL/min/1.73 m2. Serum phosphate was statistically significantly associated with severity of nephrotic syndrome independently of eGFR and age. Median (intra-quartile range) PWV was 7 m/s (4-11), with a linear trend for higher PWV across tertile of average serum phosphate over follow-up, P<.001. Twenty subjects (48%) had elevated age-specific PWV, which on logistic regression was statistically significantly associated with mean serum phosphate, OR (95% CI) per 0.1 mmol/L: 2.7 (1.5, 4.9), P = .001, which in separate analyses was independent of eGFR and other laboratory data. CONCLUSIONS: In this cohort of patients with the nephrotic syndrome serum phosphate was commonly elevated, despite well preserved eGFR, which was significantly and independently associated with elevated PWV over follow-up.
Authors: Donal J Sexton; Declan G de Freitas; Mark A Little; Tomas McHugh; Colm Magee; Peter J Conlon; Conall M O'Seaghdha Journal: Kidney Int Rep Date: 2018-03-03