Renal Flashcards
What is a renal angiomyolipoma?
A benign tumor composed of blood vessels, smooth muscle and fat.
What condition is associated with angiomyolipomas?
Tuberous sclerosis (especially when bilateral)
What is Tuberous Sclerosis and how does it present?
AD condition characterized by cortical tubers and subependymal hamartomas in the brain with seizures and mental retardation; cardiac rhabdomyomas, facial angiofibromas, and ash leaf patches may also occur.
What renal pathology is associated with von Hippel Lindau?
Bilateral renal cell carcinomas.
What is the effect of beta adrenergic action on renin?
NE binds to beta-1 receptors of JGA cells to stimulate renin release
What effect do beta blockers have on renin, angiotensin I and II and aldosterone?
Decreases all. They do not affect ACE activity.
Where is greater than 60% of water absorbed from regardless of hydration status?
Proximal tubules- it is reabsorbed iso-osmotically here
Where is the region of the highest osmolarity in the kidney?
Medullary interstitum
What action foes ADH have on urea?
It increases the number of passive urea transporters in the inner medullary collecting duct, allowing a substantial fraction of the highly concentrated urea to diffuse down its concentration gradient into the medullary interstitum. This contributes significantly to total osmolarity of the medulla which increases water-absorbing capacity of the nephron.
Why is RCC often golden yellow on macroscopic examination?
High lipid and glycogen content
From where do RCCs originate?
From the epithelium of the proximal renal tubules.
Name two risk factors associated with RCC.
Smoking and obesity (occurs typically in patients aged 60-70 yrs).
How is acute angle-closure glaucoma treated?
Acetazolamide (it inhibits carbonic anhydrase and bicarb which is present in aqueous humor)
What is the mechanism of action of acetazolamide?
Inhibits carbonic anhydrase which is found in high concentrations in the proximal tubule. By inhibiting carbonic anhydrase, acetazolamide blocks HCO3- reabsorption in the proximal tubules
What are the most common side effects associated with carbonic anhydrase inhibitors?
Somnolence, paresthesias, urine alkalinization
What is necessary in the workup of metabolic alkalosis?
Volume status and urine chloride
Name four common causes of metabolic alkalosis.
Vomiting, nasogastric suctioning, Thiazide/ Loop diuretics, mineralocorticoid excess state.
Which causes of metabolic alkalosis are saline responsive and which are not?
Saline responsive: vomiting, NG suctioning, thiazide/ loop diuretic use; unresponsive: mineralocorticoid excess
What is the most common cause of urinary tract obstruction in an elderly male?
BPH
Hos is poststerptococcol glomerulonephritis treated?
Loop diuretics and vasodilators to relieve edema and hypertension.
What is the most important prognostic factor in patients with post-streptococcal glomeurlonephritis?
Age. 95% of children recover completely, in adults only about 60% of cases resolve completely.
Describe the pathway of blood through the kidney.
Interlobar arteries –> arcuate arteries –> radial arteries –> afferent arterioles –> glomerular capillaries –> efferent arterioles –> peritubular capillaries –> interlobar veins.
What is the calculation for filtration fraction?
FF= GFR/RPF.
What happens to RPF due to severe efferent arteriolar constriction?
Substantially increased capillary oncotic pressure results in an overall decrease in GFR.
What is PAH?
An organic acid that is avidly filtered from the blood in the glomerulus and secreted by cells lining the proximal tubule of the nephron. It is used to measure renal plasma flow because it is both filtered and secreted by the glomerulus and renal tubules
What changes in secretion occur when blood concentration of PAH increases?
Secretion of PAH by proximal tubular epithelial cells increases only up to a maximum value (transport maximum of secretion enzymes)
What effect does primary hyperaldosteronism have on renin levels?
Decreases renin due to feedback inhibition
What causes secondary hyperaldosteronism?
Overproduction of aldosterone occurs secondary to increased renin synthesis
Name four causes of secondary hyperaldosteronism.
Renal artery stenosis, diuretic use, malignant hypertension, renin-secreting tumors.
What are reninomas?
Rare, small solitary benign juxtaglomerular cell neoplasms.
How do ACE inhibitors cause nephrotoxicity and acute renal failure?
Block of angiotensin mediated efferent arteriole vasoconstriction. This leads to a reduced filtration fraction and can precipitate acute renal failure in patients dependent on efferent arteriole constriction to maintain renal perfusion.
During ascent of the kidney, a horseshoe kidney gets trapped behind what vessel?
IMA
Hypoaldosteronism may cause what renal pathology?
Type IV renal tubular acidosis.