Figure 5.

Urine pellet podocyte mRNA markers by age showing accelerated detachment and podocyte stress in the group older than age 60 years. (A) The urine podocin mRNA-to-creatinine ratio is a measure of the rate of podocyte detachment relative to urine creatinine excretion analogous to the urine protein-to-creatinine ratio. The urine podocin mRNA-to-creatinine ratio in the >60-year-old group is increased 3.3-fold above the mean of younger people (<60 years; P<0.001). (B) The urine podocin-to-aquaporin2 mRNA ratio is a measure of the rate of podocyte detachment relative to detachment of another kidney cell type (distal tubule and collecting duct cells that express aquaporin2 mRNA) demonstrating that podocytes are lost preferentially to other kidney cells in the >60-year-old age group. (C) The urine pellet podocin-to-nephrin mRNA ratio is a ratio of two podocyte-specific markers that we have previously reported as a measure of podocyte stress.³² Distribution of male and female patients did not significantly differ in the various age groups. The box plots show median and interquartile ranges, and the corresponding means were compared using ANOVA with Bonferroni correction. Outliers outside the mean±2SD range are shown as circles and those outside the mean±3SD range are shown as asterisks.