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MS2 Renal > 9/24- Small Group Cases > Flashcards

9/24- Small Group Cases Flashcards

1
Q

Case)

  • 48 yo woman
  • Hx of alcohol abuse
  • Abdominal distention, swelling in feet/ankles, 15 kg weight gain, bilateral pitting edema to midcalf, hepatomegaly?, shifting abdominal dullness, multiple telangiectasia, and spider nevi, jaundiced; no asterixis
  • Hyponatremia (130)
  • BP 100/70

What is this describing?

A

Liver failure/cirrhosis

  • Cirrhosis -> NO -> vasodilation -> perceived decrease in Na concentration -> ADH release….
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2
Q

What is the significance of her 24 hour urine sodium excretion? That is, what happens if she excretes less sodium than she is ingesting?

A

Net positive sodium balance

  • Retaining sodium
  • Sodium determines water balance; here -> edema
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3
Q

What pathophysiologic factors have led to her ascites and edema? Which hormone pathways are implicated?

A

Low effective circulating volume -> activation of RAAS system -> Na and thus water retention

  • Low ECV also prompts PCT Na reabsorption Also non-osmotically-driven ADH release
  • Further increases water reabsorption
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4
Q

Are the same factors responsible for the hyponatremia?

A

Yes

  • Hyponatremic, but Na concentration depends on water volume; actually has high body Na content
  • Principally due to ADH (from relatively low effective blood volume)
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5
Q

How would you treat this patient?

A

Loop diuretic

  • Loop are the most effective for dealing with high volume
  • Loop diuretics typically result in excretion of half sodium (causes hypernatremia)
  • Loop diuretic causes water excretion > Na excretion (still causes decrease in total body Na but Na concentration will increase)

(Thiazide diuretics on the other hand cause hyponatremia?)

Fluid restriction

  • Wan’t intake > free water excreted

Sodium restriction (1-2 g/day)

  • Na follows water in the body
  • More to do with edema/ascites rather than correcting sodium level
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6
Q

Calculate her creatinine clearance in ml/min (hint: UV / P).

A

Clearance = UcrVcr/Pcr

  • U = 900mg/650mL
  • V = 650 mL/d
  • Pcr = 0.9 mg/dL

Thus, clearance = (900 mg/d)/(0.9 mg/dL)

= 1000 dL/day x 100 mL/dL / 1440 min/day ~ 69 mL/min

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7
Q

Her glucose is 70 mg/dl and BUN 6 mg/dl.

What is the calculated serum osmolarity?

  • Normal serum gap
  • What causes high serum gap
A

Calculated osmolarity = 2Na + BUN/2.8 + glucose/18

= 2(130) + 6/2.8 + 70/18 = 266

  • Normal gap = 10
  • High gap could be due to substance like ethanol/alcohol…
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8
Q

Fun fact: loop diuretics do not affect BP too much

A

(:

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9
Q

If patient has edema, what do we know about Na?

A

Total body sodium is high

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10
Q

How does BUN relate to osmolarity power/”effective osms”?

A

“Effective osms” = osmotically active solutes = 2Na + glucose/18

  • Does NOT include BUN
  • BUN freely crosses cell membranes (in contrast to Na and glucose)
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11
Q

Case 2)

  • 55 yo female comes to ER with severe epigastric abdominal pain, N/V
  • 2 wks intermittent right upper quadrant abdominal pain associated with fatty meals
  • Light colored, fatty, foul smelling stools for 2 days
  • Orthostatic hypotension
  • Slightly high temp
  • Slightly underweight
  • Mucus membranes are dry
  • Epigastric abdominal tenderness
  • Decreased bowel sounds
  • Jaundice
  • Abdominal films show calcified densities in the RUQ
A

Setup

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12
Q

What is her total Na and ECV (decreased, normal, increased? What is the cause?

A
  • Decreased ECV
  • Decreased Na (Na is a marker for ECV)
  • Hypovolemic (because ortho hypoTN, underweight, dry mucus membranes)
  • Hypovolemia probably due to vomiting
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13
Q

What does BUN:creatinine ratio > 20 indicate?

A

Volume depletion

  • Require IV fluids
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14
Q

What is the significance of her low urinary Na concentration?

A
  • Kidney is avidly reabsorbing Na to try to compensate for volume depletion
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15
Q

What would be appropriate therapy for this patient?

A
  • IV normal saline*

(should also correct metabolic acidosis, b/c urine Cl under 20)

  • Antibiotics for infection
  • Anti-emetics for nausea
  • Pain medication
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16
Q

Case 3)

  • 45 yo man with end-stage renal disease treated by hemodialysis
  • Fell down the stairs and sustained a massive hematoma in left thigh and hip
  • Brought to ER next day because weak and slow pulse
  • Vital signs: BP 140/85, pulse 50, and normal temperature
  • He had generalized weakness, was oriented, had a large bruise on his left thigh and hip
  • There were no other obvious abnormalities that had not bee present on numerous prior examinations.
  • EKG: wide QRS complex and bradycardia (HR under 60)

What is causing the wide QRS complex and bradycardia?

A

Hyperkalemia

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17
Q

Side note: How do you tell the difference between saline responsive/non-responsive metabolic acidosis?

A

Urine chloride

  • Low urine chloride indicates saline responsive (< 20)
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18
Q

What caused the hyperkalemia?

A
  • Rhabdomialysis (?)
  • Bruise itself causes hematoma, resulting in RBC lysis and K release
  • ESRD, so can’t effectively excrete K
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19
Q

What is the plan for treatment?

A
  • Calcium gluconate: stabilize the membrane
  • Insulin D50: insulin causes intracellular movement of glucose and K; give D50 (dextrose) to prevent hypoglycemia
  • Beta agonists: big dose of inhaled albuterol increases Na/K/ATPase and shifts K into cells
  • K binding resins if long time to dialysis (binds K in gut and excreted in stool)
  • IV Lasix (loop diuretic): K wasting but don’t anything if pt is anuric
  • Dialysis, but takes ~ 2 hrs to set up and this is an emergency
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20
Q

What is this patient’s anion gap?

A

AG = Na - (Cl + HCO3)

Total serum CO2 is equivalent to bicarb!!!

= 135 - (96 + 18) = 21 High AG

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21
Q

What could be causing this patient’s high AG?

A
  • Possibly lactic acidosis
  • Uremia
22
Q

Case 4)

  • 22 yo female admitted through ER after losing consciousness at home
  • Severe occipital headache and vomited twice
  • VS: BP 120/80, HR 50, normal temp, RR 22
  • Stiff neck, pupils PERRLA
  • Neuro exam showed response only to deep pain, upward plantar response, increased DTRs
  • Lumbar puncture revealed grossly bloody spinal fluid
  • Condition stabilized but she remained comatose
  • On day 4, her urine output increased to 6 L/day and her BP was 60/40

What in her labs is most concerning?

A

Severe hypernatremia

23
Q

What is causing this pt’s hypernatremia?

A

Central Diabetes Insipidus

  • Decrease in urine output
  • Sodium through the roof
24
Q

What are the main causes of DI?

A

Central:

  • Meningitis/CNS infections
  • Head trauma
  • CVA
  • Sarcoidosis
  • Hypoxic encephalopathy

Nephrogenic:

  • Inherited genetic mutations
  • Hypocalcemia and hypokalemia may induce this?
  • Obstruction causing effacement of collecting ducts
25
Q

Calculate serum osmolality on day 2

A

Osmolality = 2Na + BUN/2.8 + glucose/18

= 2(171) + 36/2.8 + 120/18 = 361.6

26
Q

What is the water deficit on day 4?

A

Pt was 60 kg on day 1 and 54 kg on day 4

  • Water deficit = 6 kg!
27
Q

List the characteristics of an ideal indicator for the msmt of glomerular filtration.

What are the advantages/disadvantages of endogenous creatinine for the measurement of GFR?

A
  • Freely filtered
  • No reabsorption or secretion
  • Not synthesized or metabolized
  • Physiologically inert
    • Easily measured**
    • Not affected by hemodynamics**

Creatinine Advantages:

  • Freely filtered
  • Physiologically inert
  • Easy
  • Pretty reliable indicator of GFR in steady state

Creatinine Disadvantages:

  • Slightly secreted (PCT); results in overestimation of GFR
  • Not reliable indicator of GFR if changing (only in steady state)
28
Q

What can you say about GFR is someone’s creatinine is increasing?

A

Nothing! Only good marker in steady state

29
Q

Case 6)

  • 35 yo female presents with headaches, weakness, lethargy, and polyria
  • She’s on no meds
  • No family illnesses
  • BP 160/95, HR 75
  • Absence of increased JVP, no edema

What stands out?

A
  • Hypertensive
  • Hypokalemia
  • High bicarb
30
Q

What is the acid-base disturbance?

Why is the PaCO2 48 mmHg?

A

Metabolic alkalosis

  • High pH
  • High bicarb (total serum CO2)
  • High PaCO2
31
Q

Are the acid-base values internally consistent (Henderson equation)

A

[H] = 24 PaCO2/HCO3 = 24(48)/(35)

= 33 nmol/L

This is equal to the given [H+], so internally consistent!

32
Q

What is the significance of the urine chloride (25 mmol/L)?

A

Saline unresponsive-ish (responsiveness considered urine Cl under 20; typically due to volume depletion)

33
Q

What are some causes of elevated urine Cl in metabolic acidosis?

Which is probable in this case?

A
  • Hyperaldosterone-type state
  • Severe hypokalemia (under 2)
  • Diuretic use
  • Bicarbonate loading (tablets, baking soda…)

This case could be hyperaldo state as indicated by high BP (order aldosterone and renin labs)

34
Q

Case 7)

  • 38 yo male alcoholic rodeo star brought to ER
  • Increasing lethargic throughout the day
  • Vital signs: BP 110/80, HR 100, R 20 and deep
  • Weighs 75 kg
  • Responsive only to pain, but can move all extremities
  • Large tender liver
  • Exam otherwise unremarkable What is notable?
A
  • Really low PaCO2 and pH
  • Elevated BUN and creatinine
35
Q

What do these urine analysis findings suggest?

A

Oxalate crystal (envelope-shaped)

36
Q

What is the acid-base disturbance?

Probable etiologies?

A

This is AG metabolic acidosis

  • A: aspirin
  • M: methanol
  • U: uremia
  • D: DKA
  • P: paraldehyde
  • I: ischemia/infarcct
  • L: lactic acidosis
  • E: ethanol glycol/ethylene
  • S: sepsis/starvation
37
Q

What is the anion gap?

A

AG = Na - (Cl + HCO3) = 138 - (100 + 8) = 30?

38
Q

What is the bicarbonate deficit?

A

Formula = TBW x (HCO3nl - HCO3msrd)

  • TBW = BW x 0.6
  • Formula: (75 x 0.6)(24-8) = 720 mmol
39
Q

Case 8)

  • Pt has new diagnosis of HTN What stands out?
A
  • Hypokalemia
  • High bicarb
  • Venous pH is high (should be more acidic)
40
Q

What is the acid base abnormality?

A

Metabolic alkalosis

41
Q

What hormone *typically* causes the urinary potassium to be 40 mmol/L?

A

Aldosterone

42
Q

The pt gives a positive FHx of HTN in his father and his grandfather, both of which began at a young age. You check renin and aldosterone levels, and those are normal. What is the most likely diagnosis?

A

Liddell’s syndrome

  • Always active ENaC channels
  • Entry of Na into cells results in negative lumen
  • Electrochemical gradient favors K exit from cell into lumen, resulting in high urine K
43
Q

Case 9)

  • 22 yo Asian male pt comes to your office with dark urine for one day
  • It is not painful and there is no foul odor
  • He is drinking a normal amt of water (1-2 L/day)
  • He believes he has had episodes of dark urine in the past
  • For the past few days, he has had a runny nose and low-grade fevers

What is notable?

A
  • Blood in urine
  • RBC casts
  • Normal albumin and complement
  • Mildly elevated creatinine (decreased renal function)
44
Q

Explain the pathophysiology that causes RBCs casts to appear in the urine?

A

Glomerular abnormality/leakage allows RBCs into tubular space

  • Tam-Horsfall protein?
45
Q

What syndrome is this?

A

Nephritic syndrome

  • Hematuria
  • RBC casts
  • Normal albumin
  • No notable edema
  • Higher creatinine/decreased GFR
46
Q

How does nephritic syndrome result in higher creatinine/decreased GFR?

A

Nephritic syndrome injures vessel, causing reactive vasoconstriction, reduced filtration SA and resultingly decreased GFR

47
Q

The timing of the dark urine with his upper respiratory infection suggests what common disease?

A

IgA Nephropathy

  • If it was 3-ish weeks later, could be post-infectious glomerulonephropathy
48
Q

What do you expect to find on IF on his kidney biopsy (IgA Nephropathy)?

A

IgA deposits in mesangium

49
Q

Does post-infectious GN have normal or low complement?

A

Low complement in post-infectious GN

50
Q

Case 10)

  • A 5 yo boy is brought by his parents to evaluate sudden onset of pretibial edema within the past 1 wk
  • The boy was previously healthy
  • No FHx of kidney disease
  • Exam is remarkable for the absence of increased JVP and generalized anasarca

What do these findings indicate?

A

Nephrotic syndrome

  • High protein (9 g/day)
51
Q

What would you expect to see on the kidney biopsy?

A

Expect minimal change disease

  • LM: no changes
  • EM: podocyte effacement
  • IF: negative

MS2 Renal (25 decks)

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