CKD I Flashcards
GFR
glomerular filtration rate. Volume of blood filtered by the glomerulus each minute
what is the normal adult GFR range?
100-125 mL/min
How can we estimate the GFR?
Using different equations such as creatinine clearance
what is the equation for creatinine clearance?
= [(140-age)x88.4x(0.85 if female)]/serum creatinine (sCr)
why is creatinine clearance important?
Since it is freely filtered by the glomerulus, it can be used as a marker of glomerular filtration rate (GFR)
What happen to serum creatine levels when renal functioning is impaired?
become elevated
what drugs can cause acute kidney injury by inhibiting vasodilation of the afferent arteriole?
- NSAIDS
- Cox-2 inhibitors
- Cyclosporine
what drugs can cause acute kidney injury by inhibiting vasoconstriction of the efferent arterioles?
- angiotensin converting enzyme inhibitors (ACE-I)
2. angiotensin II receptor blockers (ARB)
T or F: We want to constrict the afferent and dilate the efferent
FALSE; we want to DILATE the afferent and CONSTRICT the efferent
what is reabsorbed at the proximal tubule?
- Nutrients
(a) glucose
(b) amino acids - Electrolytes
(a) Na+
(b) K+
(c) Cl-
(d) bicarbonate (HCO3-)
(e) Ca2+
(f) phosphorous (PO4-)
What is secreted at the proximal tubule?
- creatinine
- uric acid
- certain drugs
What is the role of the Loop of Henle?
reabsorption of Na+, Cl-, water and Mg
What does the distal convoluted tubule reabsorb?
- Na+ and water
What does the distal convoluted tubule secrete?
K+, H+ and phosphorus
what does the collecting duct reabsorb?
Na
What does the collecting duct secrete?
K+ , which is dependent on aldosterone
which is a more sensitive marker of kidney function, Urea or creatinine ?
creatinine
Why is concentration of Urea clinically important?
serum urea to creatinine ratio > 70 may indicate dehydration
What happens to electrolytes in patients with chronic kidney disease?
- sodium/water –> edema and swelling due to inability to decrease reabsorption
- K+ increases in the blood due to inability to increase excretion from distal tubule
- Phosphorus increases in blood because not able to decrease reabsorption in proximal tubule and increase excretion from distal tubule
- Magnesium increases in the blood because not able to decrease reabsorption in the loop of henle
what do the kidneys do when it is experiencing acidosis?
reabsorb all the filtered bicarbonate into the extracellular fluid
what do the kidneys do when it is experiencing alkalosis?
the kidneys cannot reabsorb bicarbonate so it is excreted instead
when is renin released?
when the juxtaglomerular cells - located in the walls of the arterioles are stimulated (responding to changes in circulating blood volume and pressure)
hyperkalemia
increased K in the blood
hyperphosphatemia
increased phosphorous in the blood
erythropoietin (EPO)
stimulates the production of red blood cells in the bone marrow
How does the kidney know to secrete EPO?
when the oxygen levels fall below a certain level the kidneys respond by secreting EPO
What happens in CKD in regards to EPO?
EPO production goes down and the patient’s RBCs/hemoglobin decrease = anemia
What are the types of renal failure?
- Pseudo
- pre-renal
- intrinsic
- post renal
Pseudo renal failure
serum creatinine levels increase due to blocking of renal tubular secretion of creatinine. This is not “true” renal failure because drugs are blocking the secretion of creatinine
pre-renal renal failure
due to a decreased blood flow to the kidneys and hence a decreased glomerular filtration rate
intrinsic renal failure
due to structural damage to the kidney affecting either the glomerulus or the tubules; damage to the kidney itself
post-renal renal failure
obstruction to urine flow beyond the kidneys; something happening in bladder or ureter
what is the most common cause of renal failure ?
pre-renal failure which is 50-60% of all cases
what are some reasons why pre-renal failure can occur?
- intravascular volume depletion
- decline in effective blood volume
- decreased pressure in glomerulus due to drugs that vasoconstrict the afferent arteriole and vasodilate the efferent arteriole
what is Acute Tubular Necrosis (ATN)?
ischemia in the kidney producing cell damage to the tubules; leads to intrinsic renal failure. Due to medication induced causes
What is Acute Interstitial Nephritis?
inflammatory disorder of the renal interstitium (“allergic reaction”) . Caused by drugs
What is glomerulonephritis?
results from the stimulation of the immune system leading to inflammation of the glomerulus
What are 3 causes of Intrinsic AKI
- Acute tubular Necrosis
- Acute interstitial Nephritis
- glomerulonephritis
what is the cause of Post-renal AKI?
- Kidney stones
- bladder timor or obstruction
- urethral stricture/tumor
- crystal deposition in renal tubules (which can occur from certain drugs)
