SM 194a - Urine

Question 1

What kind of urine sediment is this?

What does it indicate?

Answer 1

Dysmorphic RBCs

Indicates glomerular disease (nephritic)

• Immune-complex mediated
• Anti-GBM disease
• Pauci-Immune disease

Question 2

What kind of cast is this?

What does it indicate?

Answer 2

Hyalin cast

0-5 HPF may be found in normal urine

More may result from low flow

Question 3

Normal urine specific gravity:

Answer 3

1.000 - 1.030

Question 4

What kind of cast is this?

What does it indicate?

Answer 4

Pigmented (muddy brown) cast

Indicates ATN or Rhabdomyolysis

Question 5

What kind of casts are pathopneumonic for glomerular disease

Answer 5

RBC casts

Question 6

What is the “nephrotic range” for proteinuria?

Answer 6

>3000 mg/day of protein in the urine

(normal is <30, clinical albuminuria is >300)

Question 7

What is the equation for the urine anion gap?

Answer 7

All are urine values:

K⁺ + Na⁺ + NH₄⁺ = Cl^-

Can help us evaluate non-gap metabolic acidosis

• If K+ and Na+ > Cl-, it means that NH₄+ is not in the urine
  
  • If this patient is acidemic, this means they not properly acidifying the urine; indicates RTA
• If K+ and Na+ < Cl-, it means that NH₄+ is in the urine
  
  • This is an appropriate response to acidemia caused by loss of bicarbonate in diarrhea

Question 8

What kind of cast is this?

What does it indicate?

Answer 8

White cell cast, indicates Tubular interstitial disease

• Allergic interstitial nephritis
• Pyelonephritis

Question 9

What defines microalbuminuria?

Clinical albuminuria?

Answer 9

Microalbuminuria

• If spot collection: 30-299 mcg/mg creatinine
• If 24 hour collection: 30-299 mg/24h

Clinical albuminuria

• If spot collection: >300 mcg/mg creatinine
• If 24 hour collection: >300 mg/24h

Question 10

What are the differences in the urine of a patient with prerenal AKI vs ATN (an intrinsic AKI)?

Answer 10

• Prerenal AKI = decreased perfusion to the kidney
  
  • Urine Osm > 500
    
    • High specific gravity
  • U Na < 20
    
    • A normal response to hypovolemia
  • FE Na <1
• ATN
  
  • Urine Osm < 350
    
    • Low specific gravity - Not concentrating urine well
  • U Na > 40
    
    • The kidney is having trouble reabsorbing Na+
  • FE Na > 1