13. Renal, Urinary Systems & Electrolytes

Question 1

Fever, tinnitus, and tachypnea should make you suspicious of ____ intoxication. What acid-base disorder is associated with it?

Answer 1

Aspirin intoxication

Mixed respiratory alkalosis AND AG metabolic acidosis

Question 2

What is initial treatment for severe hypercalemia (sx: weakness, GI distress, neuropsych sx) ?

Answer 2

1. Saline hydration to restore intravascular volume (patients typically vol-depleted due to polyuria and dec oral intake)
2. Calcitonin - inhibit bone resorption
   Note: bone marrow bx can be done after hydration if multiple myeloma (pancytopenia) is suspected

Question 3

When should you image for possible pyelonephritis?

Answer 3

patients with persistent clinical sx despite 48-72h of therapy for UTI

Question 4

Patients with nephrotic syndrome are at risk for developing what?

Answer 4

Hypercoagulable state –> Venous or arterial thrombosis (renal vein thrombosis most common).
Other complications of nephrotic synd: protein malnutrition, Fe-resistant microcytic anemia, vit D def

Question 5

What is the fluid of choice in a patient with severe hypovolemic hypernatremia?

Answer 5

Isotonic solutions (normal saline) aka 0.9% saline
Na must be returned to normal slowly. When giving IV fluid boluses, only isotonic solutions should be used (eg normal saline or lactated Ringers)

Question 6

Acute urinary incontinence in elderly patients may have typical presentations. Consider reversible etiologies first, esp if new onset (remember: DIAPERS). What does it stand for?

Answer 6

Delirium
Infection (UTI - acute infx are leading cause of UI in elderly)
Atrophic urethritis/vaginitis
Pharmaceuticals (a blockers, diuretics)
Psychological
Excess urine output
Restricted mobility
Stool impaction

Question 7

What is the most common form of glomerulopathy assoc with HIV?

Answer 7

Focal and segmental glomerulosclerosis - nephrotic range proteinuria, azotemia, normal sized kidneys

Question 8

Large amount of blood on UA with relative absence of RBCs on urine microscopy should make you suspect what?

Answer 8

Rhabdomyolysis - can lead to acute renal failure

Question 9

What is a risk factor for recurrent cystitis in toddlers? MOA?

Answer 9

Chronic constipation

MOA: impacted stool distends rectum –> compresses bladder –> prevents complete voiding –> urinary stasis

Question 10

What is the primary intervention proven to slow the decline in GFR once azotemia develops in patients with diabetic nephropathy?

Answer 10

intensive blood pressure control. Target BP of 140/90
Target is 130/80 if diabetic with signs of nephropathy
ACEI and ARBs are the preferred antihypertensives

Question 11

Dietary recommendations for patients with renal calculi to dec stone formation?

Answer 11

Inc fluid intake, dec sodium intake, normal dietary calcium intake.

Question 12

How can nitro cause cyanide poisoning? Sx?

Answer 12

Cyanide binds to cytochrome oxidase and inhibits mito oxid phosphorylation. Cells shift to anaerobic metabolism –. dec ATP –> lactic acidosis.
Sx - HA, confusion, arrhythmias, tachypnea, vomiting, flushing

Question 13

How can you differentiate hematuria due to glomerular vs non-glomerular causes

Answer 13

Glomerular: urine studies show proteinuria, dysmorphic RBCs or RBC casts
Non-glomerular: gross hematuria, normal looking RBCs, no signif proteinuria.

Question 14

Rupture of what part of the bladder causes urine to leak into the peritoneal cavity and can lead to chemical peritonitis?

Answer 14

Dome of the bladder - The superior and lateral surfaces of the bladder are bordered by the peritoneal cavity
Can caused refered pain to the shoulder.

Question 15

What should you suspect in a patient with palpable purpura, proteinuria, hematuria, arthralgias, peripheral neuropathy, hypocomplementemia, and hx of hep c?

Answer 15

Mixed cryoglobulinemia.

Question 16

Why should patients with severe hypercalcemia be given saline hydration aggresively?

Answer 16

Pts typically vol depleted due to polyuria (hypercalcemia-induced nephrogenic DI) and dec oral intake.
Calcitonin: inhibit bone resorption
Bisphosphonates: reduce ca levels

Question 17

Hyponatremia due to primary polydipsia is more common in pts with psych conditions. Urine osmolality is in what range?

Answer 17

<100mOsm/kg

Note: >290mOsm/kg indicates marked hyperglycemia or advanced renal failure as the cause of hyponatremia

Question 18

Pt w/hx of total nephrectomy presenting with flank pain, poor urine output, intermittent episodes of high-vol urination is due to what?

Answer 18

Urinary outflow obstruction due to renal calculi

Question 19

patients with pyelo who vomit, are old, septic, or have comorbidities require hospitalization and IV therapy. When can these patients be switched to culture-guided oral abx if sx improve?

Answer 19

48 h

Question 20

What is the most beneficial long-term management of stress incontinence?

Answer 20

Urethral sling surgery

Note: pelvic mm exercises are the first-line tx option for stress urinary incontinence due to urethral hypermobility.

Question 21

Patients with severe liver cirrhosis, acute renal failure, very low urine sodium, and bland urine sediement (no RBC, casts or protein) that does not improve with IVF should be suspected of having what?

Answer 21

Hepatorenal syndrome

- cirrhosis –> inc NO –> systemic vasodilation –> dec PVR and BP –> renal hypoperfusion

Question 22

In uncomplicated cystitis in an otherwise healthy patient with positive urinalysis should be managed how?

Answer 22

Oral TMP/SMX, nitro, or fosfomycin

Don’t need to do urine culture unless initial therapy fails

Question 23

How do you differentiate lithium-induced nephrogenic DI from psychogenic polydipsia in a psych patient?

Answer 23

Both: euvolemia and polyuria
DI: HYPERnatremic
Psychogenic polydipsia: HYPOnatremic
Note: urine osm <300mOsm = complete DI. Greater = partial DI

Question 24

Acute pyelo with labs showing urinary alk (pH>8) raises suspicion for what bacteria?

Answer 24

Proteus (most common) - urease-producing org –> struvite stones
or klebsiella

Question 25

What fluid type do you use to treat hypovolemic vs euvolemic vs hypervolemic hyponatremia?

Answer 25

Hypovolemic: 0.9% saline

euvolemic and hypervolemic - 5% dextrose in water (D5W

Question 26

In a patient with resp alkalosis, what is urine pH expected to be?

Answer 26

Inc urine pH bc kidney compensates for resp alkalosis by excreting bicarb into urine

Question 27

What is the earliest renal abnormality seen in diabetic nephropathy?

Answer 27

Glomerular hyperfiltration
Note: thickening of the glomerular BM is the first change that can be quantitated. Then mesangial expansion is seen. Nodular sclerosis si superimposed later.

Question 28

Membranoproliferative glomerulonephritis is a unique glomerulopathy that is caused by what?

Answer 28

Persistent activation of the alternative complement pathway.
IgG abs against C3 convertase of the alternative complement path –> persistent complement activation and kidney damage
Dense intramembranous deposits that stain for C3 is a characteristic microscopic finding.

Question 29

Differentiate the different types of renal tubular acidosis

Answer 29

1: cant excrete hydrogen (H)
2. cant reabsorb bicarb (B)
4: defect in the Na/K exchange (N/K) - aldo resistance
Can present as growth failure in infants. Normal AG metabolic acidosis. Labs show low serum bicarb.
Urine pH and urine electrolytes can distinguish bw the types.

Question 30

Which drugs that cause AKI are due to acute interstitial nephritis versus renal tubular obstruction

Answer 30

AIN: beta lactams, PPIs (occurs 7-10 days after exposure)
Renal tubular: acyclovir, sulfa drugs, MTX, ethylene glycol, protease inhbiitrs (1-7 days after starting drug). Crystal-induced AKI

Question 31

How can you differentiate intraperitoneal bladder rupture from extraperitoneal bladder injury in a patient with a pelvic fracture?

Answer 31

Extraperitoneal: gross hematuria, urinary retention. NO signs of peritonitis
Intraperitoneal: rupture of dome of bladder –> intraperitoneal urine leakage –> chemical peritonitis.

Question 32

SLE can affect kidneys by presenting with nephritic syndrome with low serum C3 and C4 levels. Nephrotic syndrome may also be seen. How does SLE affect the CNS?

Answer 32

Cognitive defects, storkes, seizures, or headaches (d/t vasculitis).
Note: glomerulonephritis can present with HTN, significantly low complement.