Renal SAS/Review Flashcards
The tonicity of the filtrate exiting the loop of Henle and entering the distal convoluted tubule is:
A. Hypotonic
B. Isotonic
C. Hypertonic
A. Hypotonic
A 32 year-old man presents for evaluation of hematuria found on a routine work physical. He thinks he has been told of blood in urine samples in the past. He is feeling well and does not take any medications.
- BP 145/90 HR 80, exam unremarkable
- Serum Cr 1.5, Albumin 4.0
- Urinalysis: 1+ protein, + dysmorphic RBCs
Which of the following is most likely diagnosis?
A. IgA nephropathy
B. Post-infectious glomerulonephritis
C. Minimal change disease
D. Membranous nephropathy
A. IgA nephropathy
Nephritic picture: Dysmorphic RBCs, 1+ protein isn’t that much (not nephrotic range) => IgA or Post-infectious GN
No preceding illness, recurrent blood in urine, white adult male = more likely IgA
(but IgA can also occur during or right after an infection)
What defines orthostatic tachycardia?
>30 BPM increase in pulse when going from lying down to sitting or standing
What is the equation for a patient’s water deficit?
Why would we need to calculate this?
We need to know the water deficit so we can treat hypernatremia
Which one of the following scenarios is most likely to lead to volume loss primarily from the extracellular fluid space?
- High fever
- Car accident in which there is injury to the spleen with resultant bleeding
- Bikram yoga (profuse sweating)
b. Car accident in which there is injury to the spleen with resultant bleeding
Blood loss is isotonic = lost from ECF
Sweat is hyoptonic = lost from both ECF and ICF
(Lost from ECF, then fluid moves ICF -> ECF, continues)
Why do NSAIDS increase a person’s risk of AKI?
NSAIDS inhibit prostaglandins
- -> Cannot dilate the afferent arteriole to increase perfusion to the glomerulus through autoregulation
In a patient with primary hyperparathyroidism (excess production of PTH), predict the following levels: serum calcium, serum phosphorus, urinary phosphorus
- High serum calcium, high serum phosphorus, high urinary phosphorus
- High serum calcium, low serum phosphorus, high urinary phosphorus
- High serum calcium, high serum phosphorus, low urinary phosphorus
- High serum calcium, low serum phosphorus, low urinary phosphorus
b. High serum calcium, low serum phosphorus, high urinary phosphorus
PTH inhibits phosphorous reabsorption in the kidney tubule
PTH stimulates 1,25-hydroxy-D3 production -> Ca2+ absorption in the GI tract
PTH stimulates Ca2+ reabsorption in the kidney tubule
Choose high or low for each blank
_________ NaCl delivery to the macula densa stimulates tubuloglomerular feedback and __________ NaCl delivery to the macula densa stimulates renin secretion.
High** NaCl delivery to the macula densa stimulates tubuloglomerular feedback and **low NaCl delivery to the macula densa stimulates renin secretion.
Why does hyperkalemia occur in response to acidosis?
Cellular buffering of H+ moves H+ intracellularly, and K+ extracellularly
-> Hyperkalemia
In RTA or diarrhea, the same thing happens but we lose a lot of K+ in the urine or poop, resulting in hypokalemia
What kind of AKI does rhabdomyolysis cause?
What urinalysis findings are consistent with this diagnosis?
Intrinsic AKI
- Muscle injury/cell lysis
- -> Myoglobin release
- -> Toxic to renal tubules
- -> Intrinsic AKI
Urinalysis findings
- Dipstic + for blood but no RBCs
- “Tea/cola-colored urine”
What key findings are characteristic of hepatorenal syndrome?
Hepatorenal syndrome = renal vasoconstriction in the setting of advanced liver disease and normal kidneys
- Liver damage
- Alcoholism
- Jaundice
- Urine Na < 10
- Confusion
Are ACE inhibitors more likely to cause hypokalemia or hyperkalemia?
Hyperkalemia
Anything that decreases Na+ reabsorption in the collecting duct can cause hyperkalemia
- ACE inhibitor or ARB
- MRA
- Low flow
Decreased Na+ reabsorption = Decreased K+ secretion -> Hyperkalemia
What laboratory findings are consistent with acute interstitial nephritis?
Urinalysis shows…
- WBC, WBC casts
- Urine eosinophils
History of antibiotic use w/allergic reaction (rash) is common
Note: Post-infectious GN will have RBCs and RBC casts. If a person had a recent streptococcal infection treated w/ antibiotics, look at casts to determine whether AIN (WBC, WBC casts) or postinfectious GN (RBC, RBC casts)
A 5-year old boy is brought for evaluation with new onset of abdominal swelling. His mother first noticed 2 weeks ago. She has also noticed swelling in his feet and around his eyes. You perform urine tests in the office:
- Urinalysis - 3+ protein, no blood, no RBCs, no casts
- Urine protein to urine Cr ratio – 5 grams
- Serum albumin 2.8 mg/dL (low)
If you were to perform a kidney biopsy, what would you expect to see?
- Subepithelial deposits (humps) on electron microscopy
- Nodular sclerosis on light microscopy (Kimmelsteil-Wilson nodules)
- Linear staining of glomerular basement membrane on immunoflurosescence
- Podocyte foot process fusion on electron microscopy
d. Podocyte foot process fusion on electron microscopy
This is most likely minimal change disease
Subepithelial humps = PIGN
Linear IgG GBM staining = Anti-GBM (RPGN Type I)
Nodular sclerosis = diabetic nephropathy
Choose the correct pair of urinary abnormality with the most likely diagnosis:
A. Urine sodium <20; urinary obstruction
B. FENa >1%; prerenal kidney injury
C. Muddy brown casts; acute tubular necrosis
D. Waxy hyaline casts; glomerulonephritis
C. Muddy brown casts; acute tubular necrosis
Why do some blood pressure medications decrease GFR?
ACE inhibitors and ARBs inhibit the RAAs
They decrease GFR by causing efferent arteriole vasodilation
- RAAs ususally causes efferent arteriole constriction through the effects of angiotensin II
- Medications that inhibit the RAAs inhibit efferent arteriole constriction