Chronic Kidney Disease Flashcards
What is prerenal acute kidney injury?
Resulting from renal hypoperfusion (typically dehydration) this is the most common type of AKI. Prerenal AKI arises from hypovolemia or other conditions that cause a reduced blood flow to the kidneys.
What is intrarenal acute kidney injury?
Caused by an intrinsic dysfunction of the renal parenchymal or interstitial tissue. Intrarenal injuries can be caused by vascular, microvascular, glomerular, and tubulointerstitium dysfunction.
What is postrenal acute kidney injury?
An injury resulting from an obstruction within the urinary tract affecting both kidneys. With a postrenal cause the back pressure form the impeded urine flow is the mechanism of injury.
What are the major underlying conditions that lead to CKD?
- systemic diseases: diabetes mellitus and primary hypertension are seen in most people with CKD
- Intrinsic kidney diseases: chronic glomerulonpehritis, chronic pyelonephritis, and other obstructive urological disorders
- Vascular disease: Renal artery stenosis and chronic ischemic renovascular disease
- Hereditary kidney diseases (not common): polycystic kidney disease and Alport syndrome can lead to CKD in children and some adults.
What initial compensatory mechanisms respond to CKD?
As nephrons are progressively lost in CKD, remnant nephrons respond by increasing their functionality (hyperfiltration to maintain GFR), or by increasing their mass (hypertrophy).
Hyperfiltration = increased pressure within the glomerulus and eventually to glomerulosclerosis. Increased workload of the kidneys eventually leads to injury.
What is the role of proteinuria in CKD?
Proteinuria is caused by glomerular hyperfiltration, increased glomerular capillary permeability, and loss of negative charge (which usually prevents the loss of proteins in the urine). As proteins accumulate in the interstitial space of nephrons there is a tubulointerstitial injury. Complement proteins, macrophages and other inflammatory mediators mount a response and contribute to progressive fibrosis.
What is the role of angiotensin II in CKD?
Chronic over-activation of the RAAS in CKD, as a compensatory mechanism to maintain GFR. Angiotensin II, activated through the rAAS, is a potent vasoconstrictor and causes glomerular hypertension, systemic hypertension and urine hyperfiltration. High glomerular pressure increases the glomerular capillary permeability (further contributing to the proteinuria).
