Kidney Flashcards
What 3 things increase renin release?
Reduced renal perfusion
Beta 1 stimulation
Decreased sodium and chloride delivery to the distal tubule
Where is ADH PRODUCED?
Supraoptic and paraventricular nuclei of the hypothalamus
Where is ADH ReLEASeD?!?
Posterior pituitary
What are the two mechanisms that control ADH release?
Increased osmolarity ~ increased Na shrinks osmoreceptors
Decreased blood volume ~ baroreceptors stimulate ADH release
What is the ADH V1 receptor?
Vasoconstriction ~ increased IP3 > DAG > Ca +
What is the V2 receptor for ADH?
Aquaporin 2 channels these are water channels in the collecting duct
What are the three ways to promote renal vasodilation?
Prostaglandins
Natriuretic peptide
Dopamine receptors
What is fenoldopam?
DA1 receptor agonist that increases renal blood flow
What is normal GFR?
125 mL/min
What is the filtration fraction?
20% ~ 20% is filtered by the glomerulus and 80% is delivered to the peritubular capillaries
What is the net filtration pressure?
Driving force that pushes fluid from the blood (glomerulus) into the Bowman’s capsule
NFP = glomerulae hydrostatic pressure - bowman’s capsule hydrostatic pressure - glomerular oncotic pressure
What are the 3 components of glomerular hydrostatic pressure?
Arterial blood pressure
Afferent arteriole resistance
Efferent arteriole resistance
What does constriction of the afferent arteriole cause?
Decreased RBF and Decreased GFR
What does construction of the EFFERENT arteriole cause?
Decreased in RBF BUT an increase in GFR
What does an increased plasma protein count do to RBF and GFR?
RBF ~ nada
GFR ~ decreases (more oncotic pressure)
What does a decreased plasma protein count do to GFR and RBF?
RBF ~ nada
GFR ~ increases (less oncotic pressure)
What % of ultrafiltrate is reabsorbed into the peritubular capillaries?
99% baby!
What is the autoregulation range for the kidneys?
50-180 mmHg (big range)
What is reabsorption in the kidney?!
A substance is reabsorbed back into circulation
(from the renal tubule to the peritubular caps)
What is secretion in the kidney?
A substance is transferred from the peritubular caps to the tubule!
(Caps to the tub)
What is excretion in the kidney?
Substance is removed from the body in the urine
Where does most of the sodium reabsorption happen in the nephron?
Proximal tubule
What is the main function of the descending loop of Henle?
To form concentrates or dilute urine
(Separates the handling of sodium and water)
What are the two countercurrent systems needed to created the graduates hyperosmotic peritubular interstitium?
Loop of Henle: multiplier system that creates an osmotic gradient
Vasa recta: exchanger system that maintain osmotic gradient
Where does aldosterone act?
Distal tubule and collecting duct
Where does ADH act?
Distal tubule and collecting duct
Where in the nephron does parathyroid hormone act to increase Ca reabsorption?
Distal tubule
Which aspect of the nephron is impermeable to water?
Ascending limb of loop of Henle
What do carbonic anhydrase inhibitors do?
Non competitively inhibit carbonic anhydrase in the cells that make up the proximal tubule
***this reduced reabsorption of bicarb, Na, and water
What is the clinical use of carbonic anhydrase inhibitors?
Open angle glaucoma ~ reduces aqueous humor production and IOP
High altitude sickness ~mild metabolic acidosis increases resp drive
Central sleep apnea ~ mild metabolic disorder increases resp drive
What are the complications to carbonic anhydrase inhibitors?
Metabolic acidosis
Hypokalemia
In patients with COPD, this loss of bicarb (their buffering system) may exacerbate symptoms
What is an osmotic diuretic?
Mannitol/glycerin/Isosorbide
Sugars that undergo filtration BUT NOT reabsorption. They inhibit water reabsorption in the proximal tubule (primary site) and the loop of Henle.
Which diuretic is a free radical scavenger?
Mannitol
What is the clinical use of osmotic diuretics?
Intracranial HTN
Differential diagnosis of acute oliguria (will increase UOP if prerenal injury ~ not intrinsic injury)
What are the complications of osmotic diuretics?
CHF
Pulmonary edema
If BBB is disrupted, could cause cerebral edema
What are loop diuretics?
Lasix, bumex and ethacrynic acid
Loop diuretics disrupt Na-K-2Cl transporter in thick portion of the ascending limb if Henle.
This increases the amount of sodium in the tubule and overwhelms the distal tubule’s ability to reabsorb.
What is the clinical use for loop diuretics?
Pulmonary edema
Acute kidney injury
CHF
Hypercalcemia
Hypertension
ICP
Anion overdose
What are the complications to loop diuretics?
“LOSS OF OUR boy POTASSIUM”
Hypokalemia and hypochloremic metabolic alkalosis
Hypocalcemia
Hypomagnesemia
Hypovolemia
Ototoxicity
What are thiazide diuretics?
Hydrochlorothiazide, chlorthalidone, metolazone, indapamide
Inhibit the Na-Cl co transporter in the distal tubule ~ this activates the Na-Ca Antiporter which increases Ca reabsorption ~ increasing serum Ca
What is the clinical use for thiazide diuretics?
HTN
CHF
Osteoporosis
Mobilize edema
What are complications of thiazide diuretics?
“Sweet cows thia-zide (reside) in the fields”
Hyperglycemia
Hypercalcemia
Hyperuricemia
Hypokalemic, hypochloremic metabolic alkalosis
Hypovolemia
HLD
Sexual dysfunction
What are potassium sparing diuretics?
Sprironolactone, amiloride, triamterene
Spironolactone is a aldosterone antagonist ~ blocking aldosterone at the mineralcorticoid receptor (inhibits K excretion and Na reabsorption) this is in the collecting ducts!
Amiloride and triamterene inhibits potassium secretion and sodium reabsorption in the collecting ducts (INDEPENDENT of aldosterone)
What is the clinical use of potassium sparing diuretics?
Reduce K loss in a patient receiving a loop or thiazide diuretic.
Secondary hyperaldosteronism
What are the complications of potassium-sparing diuretics?
Hyperkalemia
Metabolic acidosis
Gynecomastia
Libido changes
Nephrolithiasis
Which 3 drug classes increase the risk of hyperkalemia in a patient taking a potassium sparing diuretic?
NSAIDs
Beta-blockers
Ace Inhibitors
What are the two best tests for GFR function?
BUN and creatinine clearance
What are the two best tests for TUBULAR function?
Fractional excretion if sodium and urine osmolality
What does a BUN of < 8 indicate?
Overhydration
Decreased Urea Production (malnutrition and/severe liver disease)
What does a BUN of 20-40 indicate?
Dehydration
Increased protein input (high protein diet, GI bleed, hematoma breakdown)
Catabolism (trauma and sepsis)
Decrease GFR
What does a BUN > 50 indicate?
Decreased GFR
What is a normal BUN:Creatinine ration?
10:1
What does a BUN ratio of > 20:1 indicate?
Prerenal azotemia
What is the MOST useful indicator of GFR?
Creatinine clearance
GFR = (140-age) x (kg) / 72 x serum creatinine (mg/dL)
***in women this is multiplied by 0.85
What are the three methods to classify the severity of renal injury?!
RIFLE: risk, injury, failure, loss, end-stage
AKIN: Acute Kidney Injury Network
KDIGO: Kidney Disease Improving Global Outcomes
What are the three classifications of acute kidney injury?
Prerenal
Intrinsic
Postrenal
What are the causes and txs to Prerenal Injury?
Causes: hypoperfusion (I.e hypovolemia, decreased CO, systemic vasodilation, renal vasoconstriction)
Tx: restoration of renal blood flow, hemodynamic support, PRBCs
***an improvement in UOP following a fluid bolus is confirmation of prerenal azotemia (usually)
What are the causes and txs to intrinsic renal disease?
Causes: injury to the tubules, glomerulus, or interstitial space (nephrotoxic drugs, ischemia, NSAIDs, nephrotoxic abx)
Tx: restore renal perfusion/supportive
What are the causes and treatments for post renal injury?
Causes: result of an obstructive phenomenon (foley catheter clog, ureteral stone, neurogenic bladder)
Tx: relieve obstruction
What MAP reduces the risk of prerenal azotemia?
MAP> 65
What type of anemia results from end-stage renal disease?
NORMOCYTIC normochromic anemia
What is the MOST common cause of chronic kidney disease?
Diabetes mellitus
What is the second most common cause of chronic kidney disease?
Hypertension
What is a normal GFR?
> 90
What is stage 2 kidney disease? AKA mildly decreased
60-89 mL/min
What is stage 3 kidney disease? Aka moderately decreased GFR?
30-59
What is stage 4 kidney disease? Aka severely decreased
15-29
What is stage 5 kidney disease? Aka kidney failure?
< 15
“You hit 15, you kill the bean” 🫘
What is the first line therapy for uremic bleeding?
Desmopressin
(Uremia causes platelet dysfunction thus increases bleeding time)
What is the most common cause of death in patients with chronic kidney disease?
CAD
What is renal osteodystrophy caused by?
Decreased vitamin D production
Secondary hyperparathyroidism
What is the cornerstone of treatment?
Dialysis
What are the 5 indications for dialysis?
Volume overload
Hyperkalamia > 6
Severe metabolic acidosis
Symptomatic uremia
Overdose with a drug that is cleared by dialysis
What is the leading cause of death in dialysis patients?
Infection
Which type of dialysis is more efficient?
Hemodialysis
BUT peritoneal dialysis is favored in patients who cannot tolerate fluid shifts associated with hemodialysis
Is Sux safe in patients with renal failure?
YES! IF their potassium is within normal range
**although you should not do a sux drip
What are the most suitable NMB for renal failure patients?
Benzylisoquinolones
(Aka cisatracurium and Atracurium)
Which aminosteriod should you NOT use in renal failure patients?
Pancuronium ~ it’s primarily eliminates by kidneys
Pan > Vec > roc
Which opioid choices are not good for a renal Failure patient?
Morphine ~ metabolite is morphine 6 glucoronide
Meperidine ~ metabolite is normeperidine (can cause seizures!)
How does rhabdomyolysis and myoglobinemia affect the kidneys?
Rhabdo and myoglobinemia result from direct muscle trauma. Myoglobin binds to oxygen inside the myoctye ~ this is them freely filtered at the glomerulus. BUT in the presence of acidic urine, myoglobin precipitates ~ this causes obstruction and acute tubular necrosis
How do amnioglycosides affect the kidneys?
Aminos are MEAN to the kidneys
Once they enter the cytosol, they induce free radical damage!
What is the risk of using distilled water in a TURP?
Hemolysis
“WATER WHIPS ~ the RBCs”
What is the risk of using glycine in a TURP?
Transient blindness
“Gly-seeing”
What is the risk of using Sorbitol in a TURP?
Hyperglycemia
“ So Sweet it’s Sorbital”
What is the risk of using normal saline in a TURP?
Electrocution
“Salty sparks”
What is the preferred anesthesia for a TURP?
Spinal ~T10
(Allows for early detection of complications ~ can assess patients neurological status through procedure)
How long should resection time in a TURP be limited to?
1 hour ~ this is due to the increased absorption of irrigation fluid with the increased amount of time
Which fluids are contraindicated in a TURP if monopolar electrocautery is used?
Normal saline and LR
What is TURP syndrome?
When a large volume of hypo-osmolar irrigation is absorbed
What is the classic TURP triad?
Hypertension (increase pulse pressure)
Bradycardia (d/t reflex)
Change in mental status
Serum Na less than < 120 causes what?
Increases the risk of complications
A serum Na < 110 causes what?!
Seizure, coma, ventricular dysrhythmias
What is the classic presentation to bladder perforation?
Abdominal and shoulder pain
What is a rough estimate of blood loss during a TURP?
2-3 mL per min of resection
What are the two absolute contraindications to lithotripsy?
Pregnancy and bleeding disorders/anticoagulation.
What is nephrotic syndrome?
When kidney diseases injure the glomeruli, which ultimately allows proteins to enter the tubules ~ this allows protein to be lost in the urine
