Progression of chronic kidney disease in children
A mature rat has approximately 30 000 nephrons in each kidney. Removal of one kidney in an adult rat has little effect on the rat's blood pressure or lifespan. However, if one removes one kidney and two-thirds of the remaining kidney, the rats recover and thrive for several weeks. The remaining 10 000 nephrons are normal after surgery but soon try to compensate for the loss of the surgically removed renal mass by increasing the single nephron glomerular filtration rate. In other words, the glomerular filtration rate in the remaining glomeruli increases and there is compensatory glomerular hypertrophy. The residual glomeruli have an increase in glomerular blood flow rate and capillary hydraulic pressure compared to the control rats with a normal complement of nephrons [1,2]. The rats with a reduction in renal mass develop systemic hypertension, proteinuria, and remaining glomeruli eventually develop a lesion that resembles focal and segmental glomerulosclerosis. The increase in single nephron glomerular filtration rate is proportional to the reduction in renal mass . The timing of the reduction in nephron mass may also play a role in the severity of the insult. Unlike humans, rats continue to have nephrogenesis for the first week after birth. Rats that received a unilateral nephrectomy on day one of life develop hypertension, proteinuria, and a reduction in glomerular filtration rate normalized per kidney weight by 20 weeks of age .