SM 194a - Urine Flashcards
What kind of urine sediment is this?
What does it indicate?
Dysmorphic RBCs
Indicates glomerular disease (nephritic)
- Immune-complex mediated
- Anti-GBM disease
- Pauci-Immune disease
What kind of protiens will be detected by a dipstick?
Negatively charged proteins (mostly albumin)
What kind of cast is this?
What does it indicate?
Hyalin cast
0-5 HPF may be found in normal urine
More may result from low flow
Normal urine specific gravity:
1.000 - 1.030
What is the specific gravity that reflects “maximum urine concentration” for a normal, functioning kidney?
1.030 - equivalent to 1100-1200 mOsm
(Normal urine in a healthy person is 280-300 mOsm)
What is the most common cause of proteinuria?
Diabetes
What might cause Leukocyturia (too many white cells in the urine)?
- Contamination
- Infection
- Inflammation of the kidney or bladder
- Interstitial cystitis
- Pyelonephritis (infection of the kidney)
- Interstitial nephritis (allergic?)
What are the (broad) categories of causes of hematuria?
- GU cause
- Kidney stone
- Cancer
- Cyst
- Trauma
- Contamination
- Infection
What kind of cast is this?
What does it indicate?
Pigmented (muddy brown) cast
Indicates ATN or Rhabdomyolysis
Normal urine pH:
5-8
Why is it important to diagnose microalbuminuria in patients with diabetes?
They should be treated with an ACE-inhibitor; this will delay progressive kidney disease
What kinds of casts result from acute tubular necrosis?
Muddy brown casts
Cellular casts if whole cells are coming off
Coarsely granular casts if parts of cells are blebbing off
What kind of casts are pathopneumonic for glomerular disease
RBC casts
What is the “nephrotic range” for proteinuria?
>3000 mg/day of protein in the urine
(normal is <30, clinical albuminuria is >300)
What are the most likely causes of low urine K+ with low serum K+?
GI loss (diarrhea)
Cell shift
What are the components of normal urine on microscopy?
Few cells present
If casts, only hyalin
How will ADH affect glucose levels in the urine?
ADH dilutes the urine
If glucose is present in the urine, ADH will increase the concentration of glucose by removing water
(Ex: urine glucose concentration of 2000 mg/dL does not necessarily indicate a serum glucose of 2000 mg/dL)
A patient has a serum potassium of 2.7 meq/L (low). The urine potassium is > 40 meq/L (high). The cause of the low serum potassium is:
A. The Kidney
B. The GI Tract
C. Cell shift
D. Poor intake
A. The Kidney
High urine K+ is not an appropriate response to low serum K+ => the kidney is not reabsorbing K+ well
What is the usual cause of hematuria with red blood cell casts, proteinuria, or dysmorphic RBCs?
- Glomerular cause
- Active disease, often autoimmune, affecting and damaging the kidneys
What is the equation for the urine anion gap?
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
What kind of cast is this?
What does it indicate?
White cell cast, indicates Tubular interstitial disease
- Allergic interstitial nephritis
- Pyelonephritis
Nitrites in the urine may indicate the presence of…
Bacteria
However…
- Not all bacteria produce nitrates
- Bacteria may result from sample contamination
What defines microalbuminuria?
Clinical albuminuria?
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
What might cause hematuria with no RBCs on microscopy?
- Rhabdymyolisis
- Hemolysis
- Dilute urine (lood at specific gravity
What is isosthenuria?
Normal urine osmolality (280-300)
What are the differences in the urine of a patient with prerenal AKI vs ATN (an intrinsic AKI)?
- Prerenal AKI = decreased perfusion to the kidney
-
Urine Osm > 500
- High specific gravity
-
U Na < 20
- A normal response to hypovolemia
- FE Na <1
-
Urine Osm > 500
- ATN
-
Urine Osm < 350
- Low specific gravity - Not concentrating urine well
-
U Na > 40
- The kidney is having trouble reabsorbing Na+
- FE Na > 1
-
Urine Osm < 350
Why is high protein in the urine bad in diabetics?
Indicates increased risk of kidney failure
A UTI with a rise in creatinine indicates…
Pyelonephritis (kidney infection)
UTIs usually don’t cause a rise in creatinine
What kind of cast is this?
What does it indicate?
RBC cast
Pathopneumonic for glomerular disease
What causes ketones in the urine?
Ketones
Diabetic ketoacidosis or poor phosphate intake
What cause bilirubin in the urine?
Liver disease (check liver function tests)
How can you measure proteinuria?
- Dipstick
- Ratio
- Actual amount excreted in 24h
- But requires a 24h urine collection
