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Formatives Review Flashcards

1
Q

What two things happen when the macula densa senses increases in Na+?

A

1) afferent constriction through adenosine

2) decreased renin (don’t want more Na+ absorption)

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2
Q

tubuloglomerular feedback

A

macula densa senses increased Na+ which leads to a decrease in RPF and decrease in GFR

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3
Q

tubuloglomerular feedback effect on K+/H+ secretion

A

tubuloglomerular feedback decreases RAAS

we also know this state has more Na+

this leads to more K/H+ secretion

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4
Q

What happens to glomerular hemodynamics when you constrict the efferent arteriole?

A

Increase pressure of GC which increases GFR

You also decrease RPF

this leads to overall increase in filtration fraction

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5
Q

Filtration fraction formula

A

FF = GFR / RPF

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6
Q

How do you calculate clearance of a substrate?

A

Cx = V * Ux / Px

(make sure you make V in mL / min)

(normally given 24 hr urine volume)

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7
Q

How do you determine ECF? If ECF is elevated, what does this indicate?

A

ECF is determined by physical exam

If ECF is elevated, TBNa and TBW are elevated as well

HOWEVER, you need to check if TBNa has increased more than TBW to determine free water state

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8
Q

What is true if TBNa has increased more than TBW?

A

there is a deficit of free water

normally occurs in hypernatremia

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9
Q

What is true of free water in hyponatremia?

A

there is normally an excess of free water

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10
Q

Do thiazides impair concentration or dilution of urine?

A

they impair urinary dilution

(this can lead to hyponatremia)

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11
Q

Do loop diuretics effect urinary concentration or dilution?

A

they effect both

since they effect both, their effects largely cancel out

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12
Q

How do thiazides increase water reabsorption?

A

prostaglandin-mediated effect in the collecting duct

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13
Q

In a steady state, what is overall true?

A

urinary excretion should equal intake

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14
Q

What is true in the short term (before steady state is reached) of secreted sodium vs. intake sodium in diuretic use?

A

when you first start diuretics, you secrete a little more sodium than you take in

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15
Q

What is true of urine osmolality and urine sodium in SIADH?

A

urine osmolality is high (ADH working)

urine sodium is high

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16
Q

What happens to BP in hyperaldosteronism?

A

BP increases due to the increase in ECF expansion from increased Na/H2O reabsorption

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17
Q

How do you calculate free water deficit?

A

0.6 * weight * (serum Na - 140 / 140)

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18
Q

Does high or low plasma tonicity increase ADH?

A

high plasma tonicity

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19
Q

What is the target rise in PNa in a patient with chronic hyponatremia?

A

4-6 mEq/L increase per 24 hrs

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20
Q

Why do we give Ca2+ if there are EKG changes with hyperkalemia?

A

to stabilize the membrane potential

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21
Q

What do carbonic anhydrase inhibitors do?

A

they prevent reabsorption of HCO3-

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22
Q

How does increased serum bicarb affect potassium?

A

more H+ secreted into blood to stabilize bicarb

this leads to more K+ intracellularly and hypokalemia

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23
Q

What does liver failure result in in regard to BUN?

A

decreased BUN as liver can not produce urea

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24
Q

What marker of GFR isn’t as affected by muscle mass?

A

cystatin C

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25
Effects of NSAIDs on loop diuretics
they compete for the same transporter that secretes loops into the lumen therefore, NSAIDs lead to loop diuretic resistance
26
Why should you avoid NSAIDs with ACE/ARBs?
they can drop the GFR too low NSAIDs constrict afferent which decreases GFR ACE/ARBs prevent constriction of efferent which also decreases GFR
27
What is ACE/ARB effect on potassium levels? How?
ACE/ARB also block aldosterone (since they block AG II) this leads to decreased K+ secretion and hyperkalemia
28
How do thiazide / loop diuretics cause metabolic alkalosis?
increased Na+ delivery to the collecting duct results in increased secretion of H+
29
What is the only location in nephron that has a brush border?
the proximal tubule
30
What are aquaporin 1 channels?
proximal tubule thin descending limb *these areas are always permeable to water
31
What capillaries supply the nephron?
vasa recta / peritubular capillaries these capillaries shoot off the efferent arteriole
32
What is the thin descending tubule epithelium ?
Simple squamous
33
What is the thick ascending tubule epithelium ?
cuboidal epithelium lots of tight junctions low water permeability
34
List the glomerular capillary filtration barrier from inside out:
fenestrate capillary endothelium glomerular basement membrane podocyte (visceral epithelial cell)
35
What are proximal tubular cells closely associated with? Why?
Closely associated with peritubular capillaries so that reabsorbed solute/water can easily go back into bloodstream
36
What happens when afferent arteriole is constricted to FF?
GFR and RPF both proportionally decrease so there is no change in filtration fraction
37
What happens to afferent/efferent arterioles in massive fluid loss?
afferent dilates and efferent constricts want to maximize GFR
38
Myogenic response
renal afferent arterioles contract in response to increased stretch (BP) Ca2+ is released which triggers contraction
39
Where is ADH released from?
posterior pituitary
40
Hyperaldosterism has what effect on bicarb?
more H+ secreted = more bicarb reabsorbed into body
41
Where is sodium not reabsorbed?
descending limb of loop of Henle
42
2 effects of AG II
1) constrict the efferent arteriole to increase GFR 2) increase Na+ reabsorption in proximal tubule
43
What urine finding indicates activation of RAAS?
RAAS is activated when urine sodium is low more sodium reabsorption
44
Which diuretic is associated with hyponatremia?
thiazide diuretics
45
What can happen with chronic loop diuretic use? What can you do to help?
distal tubule hypertrophy use a thiazide to help
46
If someone has CKD, should you increase or decrease dose of CKD?
increase dose of CKD less drug is going to reach target site since RPF is decreased
47
What happens to risk of hyperkalemia as CKD progresses?
risk goes up as GFR decreases
48
Difference in calcium excretion between thiazide and loop diuretics
loop: prevent calcium reabsoprtion which leads to serum hypocalemia thiazide: increase calcium reabsorption at proximal tubule which leads to serum hypercalcemia (good for kidney stones)
49
Carbonic anhydrase inhibitors effects on potassium
increased bicarb leads to increased Na+ secretion more Na+ reaching distal tubule which results in increased K+ secretion therefore, carbonic anhydrase inhibitors can cause hypokalemia
50
What is an example of a carbonic anhydrase inhibitor?
Acetazolamide
51
Carbonic anhydrase acid-base effects
leads to metabolic acidosis due to decreased HCO3- reabsoption
52
What does low urine sodium tell you?
RAAS is activated which is leading to increased Na+ reabsorption this also means that EACV is low since RAAS is activated
53
What is a common fluid states in CHF / cirrhosis?
ECV is high BUT EACV is low water is in the wrong, interstitial spaces
54
What does hypertonic saline infusion do to RAAS?
decrease RAAS since you don't need more sodium
55
How do diuretics work in theory?
increased secretion of Na+ which water follows and decreases ECF
56
What happens to ICF and ECF with hypotonic solution?
both volume increase some ECF water moves intracellularly
57
What happens to ICF if isotonic solution is given?
there is no change no water movement
58
If isotonic solution is given, does this affect ADH? How about RAAS?
no ADH mostly responds to changes in osmolarity RAAS will decrease since you have more EACV
59
What does hypertonic solution do to ADH?
increases ADH secretion want to keep free water to balance the increase in solute
60
What does high urine osmolality indicate? What does high urine sodium indicate?
High urine osmolality = ADH active (stopping excretion of water) High urine sodium = RAAS active (water is being reabsorbed)
61
How do we define hyponatremia with lab values?
PNa < 135 mEq/L
62
What drugs can often cause SIADH?
SSRIs
63
When do you worry about hyponatremia?
When PaNa < 125 this will lead to intracranial swelling and CNS symptoms
64
When do we worry about osmotic demyelination syndrome?
when correcting hyponatremia too quickly
65
What 4 medications can you use to treat hyperkalemia?
albuterol insulin / glucose bicarbonate potassium binding resins
66
Why do we use urea to treat SIADH?
urea acts as an osmotic diuretic and will increase water secretion
67
Why do we use vaptans to treat SIADH? What is one of their downsides?
block V2 receptors for ADH *they are expensive and hepatotoxic
68
Do you use loops or thiazides with SIADH?
loops
69
What 2 factors does ADH effect?
1) water reabsorption 2) urea reabsorption *the water follows the urea*
70
Does hypokalemia or hyperkalemia cause a decreased response to ADH?
hypokalemia
71
What can raise BUN?
high protein intake bleeding glucocorticoids
72
What approximates GFR? What approximates RPF?
Inulin approximates GFR PAH approximates RPF
73
What does bicarbonuria do to potassium secretion?
increases potassium secretion at the collecting duct
74
Higher urine concentration = *** urine osmolarity
higher urine osmolarity
75
In what setting are osmotic diuretics, such as mannitol, commonly prescribed?
intracranial pressure
76
How do osmotic diuretics work?
work in PCT to create hyperosmolar urine hyperosmolar urine leads to increased water secretion
77
What is another name for DCT? Why?
diluting tubule no aquaporin to move water dilute through pulling solutes out!
78
What does membranous nephropathy show on light microscopy?
spike and dome pattern (train-tracking)
79
Why does ADH constrict vessels through V1?
in states of low volume and shock, you want to constrict to raise BP
80
What type of antibiotics can cause AKI? What is associated with this class of drugs?
aminoglycosides hearing loss
81
What is a sign of rhabdomyalysis in urine?
positive dipstick but negative for RBCs this indicates that myoglobin is present
82
What drug can cause rhabdomyalysis?
statins
83
If you have a high anion gap with normal pH, what do you know is present?
know that metabolic acidosis is present need to look for a mixed alkalosis to balance pH
84
Where does IgA nephropathy deposit?
mesangium
85
If an XR does not show a kidney stone, but patient has signs of kidney stone, what is most likely diagnosis?
uric acid stones they are radiolucent
85
What are signs of uremia which indicate you may need to start dialysis?
pericardial friction rub asterixis somnolence / alteration of consciousness slower uremic fetor (ammonia breath) also: malnourished, brusing, etc.
86
How can you determine ATN vs. prerenal azotemia?
prerenal has an elevated BUN ratio and normally signs of hypoperfusion (low BP) ATN has a normal BUN
87
What are the stages of aspirin overdose?
early: respiratory alkalosis late: mixed disorder (respiratory alkalosis with metabolic acidosis)
88
Where does PTH facilitate Na-Ca2+ exchange / calcium reabsorption?
in the DCT
89
If you are volume overloaded, what is true of TBNa?
increased
90
If aldo is high, what is true of renin?
if aldo is high, renin is low negative feedback loop
91
When more H+ is secreted through collecting duct, what happens to serum bicarb?
serum bicarb levels increase
92
What hormones affect sodium reabsorption in the proximal tubule?
Angiotensin 2 will increase sodium reabsorption by increasing the activity of Na-K-ATPase and NHE ANP and Dopamine will decrease sodium reabsorption by decreasing Na-K-ATPase activity
93
What effect does increased serum potassium have on sodium reabsorption in the DCT?
increased serum K+ decreases the action of the Na-Cl transporter decreases Na reabsorption (almost acts as a mild diuretic)
94
How in general does ANP work?
decreases activity of Na/K ATPase which then decreases sodium reabsorption leads to increased secretion of Na+ and H2O
95
Where are ROMK channels
thick ascending tubule (backflow) principal cells
96
Where are BK channels
principle and intercalated cells
97
What 2 factors prevent concentration gradient from being washed out by plasma?
low medulla blood flow blood flow in the hairpin shape which matches
98
Where is carbonic anhydrase found besides the PCT?
found in intercalated cells works to breakdown H2Co2 to drive the H+ ATPase on intercalated cells (produces a HCO3- molecule)
99
What 2 values are associated with pre-renal azotemia?
increased BUN: Cr ratio decreased BP (lack of perfusion)
100
If a patient has proteinuria but normal serum albumin what does this indicate?
this is NOT a glomerular disease! (could be a tubular or interstitial disease)
101
When do you use winter's formula?
in metabolic acidosis will tell you if their is appropriate CO2 response (just because CO2 went down it might not have went down the appropriate amount)
102

Nephrology (6 decks)

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