Renal/Urinary Flashcards
What is the renal threshold for glucose in dogs and cats?
Dog: 180 mg/dL
Cat: 300 mg/dL
What are the two main causes of hypocalcemia in dogs/cats with CKD?
1) hyperphosphatemia
2) Calcitriol deficiency
Where is renin release?
Juxtaglomerular cells
Granular cells?
Draw and label the juxtaglomerular apparatus. What are the three major components of juxtaglomerular apparatus?
1) Macula densa
2) Juxtaglomerular cells
3) Extra-glomerular mesangial cells
In the kidney, where does ammoniagenesis mainly happen? Which amino acid is the source?
Proximal renal tubule
Glutamine
True or False: Proteinuria is a negative prognostic indicator in both canine and feline CKD.
True
What is the flow in the hemodialysis filter that can optimize the dialysis efficiency?
Countercurrent flow
What are the four mechanisms of extracorporeal therapy?
Diffusion
Convection
Absorption
Seperation
What is the diffusion based on to make the particles move?
Concentration gradient
Membrane charististics
What is the mechanism behind convection in extracorporeal therapy?
Solvent drag
* Hydrostatic pressure gradient
What are the four factors to consider when you determine the modality of the extracorporeal therapy?
Protein-binding
Molecular weight
Volume of distribution
Patient’s volume status
What are the follow extracorporeal therapies based on?
Intermittent hemodialysis (IHD)
Hemoperfusion (HP)
Continuous venovenous hemofiltration (CVVH)
Continuous venovenous hemodialysis (CVVHD)
Continuous venovenous hemodiafiltration (CVVHDF)
Slow continuous ultrafiltration (SCUF)
Intermittent hemodialysis (IHD) - diffusion
Hemoperfusion (HP) - absorption
Continuous venovenous hemofiltration (CVVH) - convection
Continuous venovenous hemodialysis (CVVHD) - diffusion
Continuous venovenous hemodiafiltration (CVVHDF) - convection + diffusion
Slow continuous ultrafiltration (SCUF) - convection?
Therapeutic plasma exchange (TPE) - separation
True or False: Smaller molecules are better removed by diffusion, and larger molecules are better removed by convection.
True
True or False: During hemodialysis for ethylene glycol intoxication, only ethylene glycol is removed and the metabolites remains in the system.
False
Both ethylene glycol and its metabolites are removed
How many percentage of colloid osmotic pressure contributes to the total osmotic pressure?
0.5%
What are two types of water loss?
Obligatory water loss: water needed to excrete the daily renal solute load
Free water loss: water excreted unaccompanied by solute under the control of antidiuretic hormone [ADH]
In dogs, how many percentage increase of osmolality will induce thirst?
1 - 3%
Which molecule can be filtered through the glomerulus more easily, the positively charged or negatively charged one?
Positively charged one
Because glomerulus is negatively charged
What is the size selectivity limit of glomerulus?
4 nm in diameter
Which layer contributes to the glomerulus size selectivity?
1) Capillary endothelium
2) Glomerular basement membrane
3) Visceral epithelial cells (podocytes)
2) Glomerular basement membrane
The lamina rara interna and lamina rara externa contain polar non-collagenous proteins that contribute to the negative charge of the filtration barrier.
The lamina densa contains nonpolar collagenous proteins that contribute primarily to the size selectivity of the filtration barrier.
The glomerulus has similar net filtration pressure than systemic capillary, but why glomerulus has such high filtration rate than capillary?
1) The glomerulus has much bigger surface area for filtration
2) The permeability for electrolytes are much greater (100x) than systemic capillaries
Both contribute to higher ultrafiltration coefficient Kf
What are the changes in renal blood flow and GFR in each situation?
What are the effects of norepinephrine, angiotensin II and dopamine and ADH on the renal blood flow and GFR?
NE: RBF↓ GFR↑
Angiotensin II: RBF↓ GFR↑
Dopamine: RBF↑ GFR no change
ADH: RBF↓ GFR↑
True or False: norepinephrine, angiotensin II and ADH cause renal arterioles vasoconstriction, and stimulate the production of (PGE2 and PGI2), which counterbalances by their vasodilation effect.
True
True of False: ADH causes vasoconstriction on both afferent and efferent arterioles, and prostaglandin E2 cause vasodilation on both afferent and efferent arterioles.
False
ADH only cause vasoconstriction on efferent arterioles; prostaglandin E2 only cause vasodilation on afferent arterioles.
What is the equation for GFR?
What is normal GFR for dogs and cats? What about renal plasma flow (RPF) and filtration fraction (FF)?
1) GFR: Dog 3-5 ml/kg/min Cat 2.5-3.5 ml/kg/min
2) RPF: Dog 7-20 ml/kg/min Cat 8-22 ml/kg/min
3)FF: Dog 0.32-0.36 Cat 0.33-0.41
Name two substances that can used to evaluate GFR.
Creatinine
Inulin (a polymer of fructose)
Fill out the blank: In the kidneys, between perfusion pressures (MAP) of __________, GFR and RBF vary less than 10%. The ________ is the site to regulate the pressure.
80 - 180 mmHg
Afferent arterioles
What are the two autoregulation of nephrons? Which one is faster?
Myogenic mechanism
Tubuloglomerular feedback
Myogenic mechanism is faster
What is the RBF when compared to total cardiac output?
20% of cardiac output
How do you assess RBF based on RPF?
Which route does water mainly pass through in the renal tubule, paracellular route or transcellular route?
Transcellular route
Name four renal transport processes and an example for each one of them.
Passive diffusion -
Facilitated diffusion - glucose, amino acid
* it is a saturated process
Primary active transport - H+-ATPase at the luminal side, Na,K-ATPase at the basolateral side
Secondary active transport - (e.g. glucose-Na, Na-H)
True or False: Na is reabsorbed with glucose, amino acids, phosphate, and bicarbonate in the proximal renal tubule.
True
Which tubular transport maximum (Tmax) is the lowest, glucose, phosphate or amino acid?
Phosphate
Explain why during dehydration, patient’s BUN may increase but not creatinine?
50% or urea is passively reabsorbed in the proximal renal tubule. When patient is dehydrated, tubular flow decreases, there is increased water reabsorption and subsequent urea reabsorption via the solvent drag.
True or False: The ascending limb of Henle’s loop is impermeable to water.
True
So NKCC2 can transport the electrolytes without carrying water → important step for urinary concentrating mechanism
There are three segments of collecting ducts, what are they? Which segment is permeable to urea?
Cortical, outer medullary, inner medullary
Inner medullar collecting duct is permeable to urea
* its urea permeability is increased by ADH
Why under normal condition, the medullary interstitium can maintain its hyperosmotic gradient?
The countercurrent exchange of vasa recta → can remove water while keep the solutes in the interstitium
Where is erythropoietin EPO produced in the fetus and adults?
Fetus: liver
Adults: peritubular cells in kidneys
Name three conditions that will increase renin release.
1) Decreased renal perfusion pressure
2) SNS stimulation & increased circulating catecholamines level
3) Decreased Cl concentration at the distal tubular flow
In the RAAS system, which step is the rate limiting step?
Renin converts 𝜶2-globulin angiotensinogen to angiotensin I
True or False: The release of renin is inhibited by a direct effect of angiotensin II on the granular cells.
True
How does angiotensin II cause increase proximal renal tubular sodium absorption?
Stimulating the Na-H antiporter in luminal membranes of proximal tubular cells.
Name 5 functions of angiotensin II
1) arterial vasoconstriction
2) inhibit renin
3) stimulate aldosterone production
4) stimulate ADH release
5) stimulate mesangial cells to produce PGE2, PGI2
6) Increase proximal renal tubular Na reabsorption
7) Cause afferent and efferent renal arterioles constriction
Where is kidney convert calcidiol to calcitriol?
Proximal tubular cells
Name 5 different types of diuretics, which part of the renal tubules do they work on and their MOA.
1) Carbonic anhydrase inhibitor - acetazolamide
2) Osmotic diuretic - mannitol
3) NKCC2 inhibitor - furosamide, torsamide
4) Thiazide - thiazide
5) Aldosterone receptor antagonist - spironolactone
What is MOA of Acetazolamide?
According to IRIS CKD staging, what is the UPC cutoff for proteinuria in dogs and cats? What about the cutoff for pre-hypertensive and hypertensive?
UPC
Dog: > 0.5
Cat: > 0.4
Blood pressure
Pre-hypertensive 140-159
Hypertensive 160-179
What is the creatinine range for grade II AKI?
1.7-2.5 mg/dL
According to IRIS AKI grading system, what is the definition of fluid responsive?
UOP > 1 ml/kg/hr over 6 hours, or creatinine decrease to baseline over 48 hours
What are the two subgrading for AKI in IRIS guidelines?
1) Non-oliguric or Oligo-anuric
2) Requiring RRT