Urine Analysis

Front 1

What are the 3 elements we look at in urinalysis?

Back 1

Appearance
Dipstick
Sediment

Front 2

What are the components of appearance, dipstick, and characteristics?

Back 2

*Appearance: Color, Turbidity, Odor.

*Dipstick: Specific gravity, pH, Protein, Glucose, Blood, Nitrite, Leukocyte esterase

*Sediment: Cells, Casts, Bacteria, Yeasts, Parasites, Crystals, Artifacts, Mucus threads.

Front 3

Urine color--what does cloudy mean?
red/red-brown?
yellow-brown?
orange?
green?

Back 3

*Cloudy: Cells (WBC, bacteria, epithelial cells), crystals

*Red or red brown: RBC, hemoglobin, myoglobin

*Yellow-Brown Urine: Bilirubin (conjugated; NOT bound to albumin).

*Other colors: Orange (rifampin); Green (amitriptyline, propofol) etc.

Front 4

What is the specific gravity of urine?
How does it compare to osmolality?

Back 4

*Higher specific gravity = more concentrated urine.

Front 5

What can specific gravity help you discern?

Back 5

*Barometer of dipstick element concentrations

*Water disorders

*Volume status of a patient

Front 6

What is the normal response to drinking too much water?

Abnormal?

Back 6

*Normal response to too much water (hyponatremia):
1) Remove water --> dilute the urine!
-Urine will have low osm = low specific gravity.

*Pathology:
1) Unable to excrete water (ADH is present)
2) Unable to excrete enough water (Too much water intake...like a marathon runner)

Front 7

What is the normal response to drinking too little water?

Abnormal?

Back 7

*Normal response to too little water (hypernatremia):
1) Retain water --> concentrate the urine!
-Urine will have high urine osm = high specific gravity.

*Pathology:
1) No stimulus to hold onto water (No ADH available=Diabetes insipidus).
2) Kidneys unable to hold onto water (ADH present but kidney can’t get rid of water).

Front 8

What are hyponatremia and hypernatremia?

How does urine specific gravity help identify the cause?

Back 8

Water disorders (Abnormal Na concentration)

1) Hyponatremia:
*High specific gravity ~ Concentrated urine --> Diluting defect (inability to excrete water)
*Low specific gravity ~ Dilute urine --> Diluting capacity exceeded.

2) Hypernatremia:
*High specific gravity --> Lack of water intake.
*Low specific gravity --> Concentrating defect (inability to hold onto water).

Front 9

What does specific gravity tell you in a state of hypovolemia?

Back 9

*Hypovolemia:
1) Aldosterone
2) ADH

*Presence of ADH is indicated by a high specific gravity.

Front 10

What is normal urine pH?

Back 10

*Physiologic urine pH = 4.5 - 8.0
*Usual pH: 5-6

*pH should be determined promptly after urine collection because it can change with time.

Front 11

What kind of situations cause a high urine pH?

Back 11

1) Urea-splitting bacteria.
2) Urinary stones: struvite stones.
3) Metabolic alkalosis --> exogenous alkali.

4) Metabolic acidosis:
-Type I RTA (Renal Tubular Acidosis): Acidifying defect of the distal tubule.

Front 12

What situations cause a low pH?

Back 12

*Normal finding due to organic acids from glucose metabolism.

*Paradoxical aciduria with metabolic alkalosis.

Front 13

What are normal urinary protein levels?

Back 13

*Normal level < 150 mg protein/24 hr: usually 40-80 mg/day.

*Microalbuminuria: urinary albumin = 30-300 mg/day (normal albumin <30).

*Strips are highly sensitive to albumin but NOT to other proteins (light chains, amino acids etc).

Front 14

Dipstick readings correspond to what protein levels?

What can cause false positive protein readings? 3

Back 14

Front 15

In what situations would you see glucose in the urine?

Back 15

1) Nonfasting urine dipstick.

2) Diabetes (May also see ketones).

3) Other: Disorders of proximal tubular glucose reabsorption, e.g. Fanconi’s syndrome.
*Consider Fanconi if there's a non-diabetic spilling glucose.

Front 16

How do we detect blood in the urine?

How do we actually see the CELLS?

Back 16

*Detection is based on the peroxidase activity:
-Hemoglobin
-Myoglobin
-you don't actually see the RBCs

*Microscopic examination of the urine sediment is required to confirm presence of RBCs.

*Contamination of urine is a possibility (menstruation, UTI).

Front 17

What does it mean if you have nitrites in your urine?

Back 17

*Gram negative bacteria are present!
*False negative result: occurs when urine has not been retained in the bladder long enough (~ 4 hours) to permit sufficient production of nitrite.

Front 18

What does it mean if you have leukocyte esterase in your urine?

Back 18

*Esterase is released by WBCs.
1) Urinary tract infection.
2) Interstitial nephritis (especially if no bacteria are present).
3) Tuberculosis.

Front 19

How do you obtain the urine sediment?

Back 19

*Take 10 ml of clean-catched midstream urine.

*Centrifugation: 5 minutes @ 1500-2000 rpm in a urine collection tube.

*Decantation of supernatant.

*Pellet resuspension in remaining urine.

Front 20

What are 5 kinds of cells you may see in the urine?

Back 20

Red blood cells (RBC)
White blood cells (WBC)
Renal tubular epithelial cells (RTE)
Squamous epithelial cells
Bladder cells

Front 21

What are casts? What 5 kinds might you see in the urine?

Back 21

*Formed in renal tubules, mostly in distal nephron.

RBC casts
WBC casts
Granular casts
RTE casts
Hyaline casts

Front 22

What are these and what situations may cause them to be in the urine?

Back 22

*RBCs!
*More than 2-3 per hpf (field) are pathologic.

1) Urinary tract infection
2) Urinary stones
3) Glomerulonephritis
4) Bladder pathology
5) Tumors

Front 23

Back 23

Glomerulus. Square indicates a capillary wall. Note that RBCs have to get from the capillary to the Bowman's space iot get into the urine.

Front 24

Back 24

*Shows a RBC breaking thru the GBM and making it into the urinary space.
*This cell will be dysmorphic from the trauma of breaking thru.
*Glomerulonephritis.

Front 25

Back 25

*Dysmorphic RBCs in glomerulonephritis.

Front 26

Back 26

*RBC cast. Long, tubular shape. Some cellular elements are visible inside.

Front 27

Back 27

*High power RBC cast. Note the biconcave cells in the cast.

Front 28

What is this? How many should you see in the urine normally? What situations will cause them to be elevated?

Back 28

*WBC. Perfectly round with granularity. Can't be more specific than that.
*More than 4 WBCs per hpf are pathologic.

1) Infection (pyelonephritis)
2) Acute interstitial nephritis

Front 29

Back 29

*WBC cast. Kind of hard to distinguish from a RBC cast, but note that all the surrounding cells are WBCs.
*Be suspicious of pyelonephritis or acute interstitial nephritis.

Front 30

What are these and what causes them to be in the urine?

Back 30

*Rods, most likely gram negatives.

1) Contamination
2) Colonization
3) Infection (you'll also see WBCs if this is the case).

Front 31

Back 31

*Renal tubular epithelial cells.
*Some elongated, football shaped. Nucleus is off to the side.
*Seen in acute tubular necrosis, early stage of injury.

Front 32

Back 32

*Renal tubular epithelial cells.
*Seen in acute tubular necrosis, early stage of injury.
*Epithelial cells that line the tubules
*Ischemia/ toxic injury

Front 33

Back 33

NORMAL renal tubules.

Front 34

Back 34

*Disruption of tubular lining in ATN. These cells will slough off into the urine.

Front 35

Back 35

*Muddy brown casts in ATN. Membranes of these cells have been disrupted.
*Seen in acute tubular necrosis, LATE stage of injury; cells have been seriously degraded.

Front 36

Back 36

*Light, slightly granular, hard to see. Hyaline cast!
*Not pathologic.
*Tamm-Horsfall protein is secreted by the tubules.

Front 37

What is this?
When do you see this?

Back 37

*Fatty casts seen in nephrotic syndrome!

Front 38

Back 38

*Fatty casts under polarized light showing "Maltese cross sign."
*Seen in nephrotic syndrome!

Front 39

When do you see these in the urine?

Back 39

*Crystals!
1) Nephrolithiasis (most common).
2) Ethylene glycol toxicity.
3) Precipitation in old (cooled) urine.