Urinalysis Chapter 5: Physical Examination of Urine

Urine color variation

colorless to black

due to normal metabolic functions, physical activity, ingested materials or pathological conditions

Colorless urine

• cause: recent fluid consumption

• Lab correlations: commonly observed with random specimens

Pale yellow urine

Cause:

• Polyuria or diabetes insipidus

  • Lab Correlations: increased 24 hr volume and low specific gravity

• Diabetes mellitus

  • Lab correlations: elevated specific gravity and positive glucose test result

• Dilute random specimen

  • recent fluid consumption

Dark yellow urine

Cause:

• concentrated specimen

  • may be normal after strenuous exercise or in first morning specimen

• B complex vitamens

• Dehydration

  • fever or burns

• Bilirubin

  • yellow foam when shaken and positive chemical test results for bilirubin

• Acriflavine

  • negative bile test results and possible green fluorescence

• Nitroflurantoin

  • antibiotic administered for UTI

Orange-Yellow urine

Cause:

• Phenazopyridine (Pyridium)

  • drug commonly administered for UTIs

• Phenindione

  • anticoagulant, orange in alkaline urine, colorless in acid urine

• Sulfasalazine (azulfidine)

  • anti-inflammatory drug

Yellow-Green Urine

Causes:

• Bilirubin oxidized to Biliverdin

  • colored foam in an acidic urine and false-negative chemical test result for bilirubin

Green Urine

Cause:

• Pseudomonas infection

  • positive urine culture

• Asparagus consumption

Blue-Green Urine

Cause:

• Amitiptyline

  • antidepressant

• Methocarbamol (robaxin)

  • muscle relaxant, may be green brown

• Clorets

• Indican

  • bacterial infections, intestinal disorders

• Methylene Blue

  • fistulas

• Phenol

  • when oxidized

• Propofol

  • anethetic

• Familiial hypercalcemia

  • “Blue diaper syndrome”

• Indomethacin

  • nonsteroidal anti-inflammatory drug

Pink-Red Urine

Causes:

• RBCs

  • cloudy urine with positive chemical test results for blood and RBCs visible microscopically

• Hemoglobin

  • clear urine with positive chemical test results for blood; intravascular hemolysis

• Myoglobin

  • clear urine with positive chemical test result for blood; muscle damage

• Beets

  • alkaline urine of people who are genetically susceptible

• Rifampin

  • Tuberculosis medication

• Menstrual contamination

  • cloudy specimen with RBCs, mucus, clots

Port-Wine Colored Urine

Cause:

• Porphyrins

  • negative test for blood, may require additional testing

Red-Brown Urine

Cause:

• RBCs oxidized to methemoglobin

  • seen in acidic urine after standing; positive chemical test result for blood

• Myoglobin

Brown-Black urine

Causes:

• Homogentistic acid (alkaptonuria)

  • seen in alkaline urine after standing; specific tests are available

• Malignant melanoma, melinin or melanogen

  • urine darkens on standing and reacts with nitroprusside and ferric chloride

• Phenol derivatives

  • interfere with copper reduction tests

• Argyrol (antiseptic)

  • color disappears with ferric chloride

• Methyldopa or levodopa

  • antihypertensive

• Metronidazole (Flagyl)

  • darkens on standing, intestinal and vaginal infections

• Chloroquine and primaquine

  • antimalarial drugs

• Methocarbamol

  • muscle relaxant

• fava beans, rhubarb, or aloe

What color would you expect the urine with Polyuria or diabetes insipidus?

pale yellow

What color would you expect the urine for a patient with Diabetes mellitus?

pale yellow

What color would you expect the urine for a patient with B complex vitamin useage?

dark yellow

What color would you expect the urine for a patient that is dehydrated?

dark yellow

What color would you expect the urine for a patient with fevers or burns?

dark yellow

What color would you expect the urine with Bilirubin

dark yellow

What color would you expect the urine with acriflavine

dark yellow

What color would you expect the urine with Nitrofurantoin

dark yellow

What color would you expect the urine with Phenazopyridine

orange-yellow

What color would you expect the urine with Phenindion

orange-yellow

What color would you expect the urine with sulfasalazine?

orange-yellow

What color would you expect the urine with oxidized bililrubin?

oxidized to biliverdin
yellow-green

What color would you expect the urine for a patient with PSeudomonas infection?

green

What color would you expect the urine for a patient who ate asparagus

green

What color would you expect the urine with amitiptyline

blue-green

What color would you expect the urine for a patient taking Methocarbamol/Robaxin?

blue-green

What color would you expect the urine for a patient chewing Clorets

blue-green

What color would you expect the urine with indican

blue-green

What color would you expect the urine with methylene blue

blue-green

What color would you expect the urine with phenol

blue-green

What color would you expect the urine with propofol

blue-green

What color would you expect the urine for a patient with familial hypercalcemia?

blue-green
“blue diaper syndrome”

What color would you expect the urine with Indomethacin

blue green

What color would you expect the urine with RBCs

pink-red

What color would you expect the urine with hemoglobin

pink-red

What color would you expect the urine with myoglobin

pink-red to red-brown

What color would you expect the urine of a patient who ate beets

pink-red

What color would you expect the urine with Rifampin

pink-red

What color would you expect the urine with menstrual contamination

pink-red

What color would you expect the urine with porphyrins

port wine color

What color would you expect the urine with oxidized RBCs

oxidized to methemoglobin
red-brownWhat color would you expect the urine with

What color would you expect the urine with homogentisic acid

brown-black

What color would you expect the urine with malignant melanoma

brown-black

What color would you expect the urine with phenol derivatives

brown-black

What color would you expect the urine with argyrol antiseptic?

borwn-black

What color would you expect the urine with methyldopa or levodopa

brown-black

What color would you expect the urine with Metronidazole

Flagyl
brown-black

What color would you expect the urine with chloroquine or primaquine

antimalarial drugs
brown-black

What color would you expect the urine with methocarbamol

brown-black

What color would you expect the urine of a person who ate fava beans, rhubarb or aloe

brown-black

How to observe urine color

• good light source

• looking against a white background

What causes the yellow color of urine?

Pigment called Urochrome

Urochrome

yellow pigment that is the product of an endogenous metabolism, ecxtreted at a constant rate

Thyroid conditions color change

more yellow- increased urochrome

What causes urochrome to increase artificially?

• thyroid conditions

• fasting

  • urine standing at room temperature

What can estimate urine concentration>

color

Pink pigment of urine

Uroerythrin

When is Uroerythrin seen

refrigerated urine samples due to precipitation of amorphous urates in an acid urine

orange-brown normal urine caused by…

urobilin- oxidation product of normal urinary consituent urobilinogen
in a non-fresh urine

What microbial test should be considered with a positive bilirubin result?

Hepatitis virus

What test is altered by exposure to light?

Bilirubin

Yellow foam when shaken

phenazopyridine
bilirubin

fresh urine that is brown can indicate…

glomerular bleeding

red and cloudy urine

RBC present likely

red and clear urine

No RBC, likely hemoglobin or myoglobin

how to differentiate hemoglobinuria and myoglobinuria

examining the plasma

Hemoglobinuria- red plasma from RBC breakdown

Myoglobinura- no change in plasma color, from skeletal muscle breakdown

Urine Clarity

transparency or turbidity of a urine specimen

How to determine clarity of urine sample?

visually eaming in front of light source

Clarity types

Clear- no visible particulates, transparent

Hazy- few particulates, print easily seen through urine

Cloudy- many particulates, print blurred through urine

Turbid- print cannot be seen through urine

milky- may precipitate or be clotted

Normal clarity urine

freshly voided: clear, especially if midstream catch

alkaline urine: precipitation of amorphous phosphates and carbonates may cause white cloudiness

Squamous epithelial cells and mucus in urine: clarity

hazy but normal

allowed to stand urine sample: clarity

improper preservation leads to bacterial growth with increases turbidity

refrigerated urine sample: clarity

thick white turbidity caused by precipitation of amorphous phosphates and carbonates (normal)

thick pink brick color turbidity caused by precipitation of amorphous urates (uroerythrin)

specific gravity

kidney’s ability to concentrate the glomerular filtrate by selectively reabsorbing essential chemicals and water from the glomerular filtrate

Isosthenuric specific gravity

1.010hy

Hyposthenuric specific gravity

<1.010h

Hypersthenuric specific gravity

>1.010

Normal ranges for specific gravity

1.002-1.035 depending on hydration

Specific gravity below 1.002

probably not urine

Refractometer

determines the concentration of dissolved particles in a specimen by measuring refractive index

by comparing the velocity of light in the air with the velocity of light in a solution

A specimen containing 1 g/dL protein and 1 g/dL glucose has a specific gravity reading of 1.030. Calculate the corrected reading

1.023

Specific gravity calcuation to account for glucose and protein

subtract 0.003 for each gram of protein and 0.004g for each gram of glucose

Calibration of specific gravity solutions

Water: 1.000

5% NaCL: 1.022

9% sucrose: 1.034

Specific gravity of greater than 1.040 could indicate

IV pyelogram (radiographic contrast media) use

Dextran or high MW IV fluids

Osmolality vs specific gravity

Specific gravity depends on number of particles present in solution and density

osmolality is only affected by number of particles present

Osmolality substances of interest

small molecules: sodium, chloride, urea

Omole

1g MW of a substance divided by the number of particles into which it dissociates

Colligative properties used in osmolarity

• lowering freezing point

• higher boiling point

• increased osmotic pressure

  • lower vapor pressure

A2O Advanced Automated Osmometer

uses freezing point depression to measure osmolality, automated for urine and serum

Reagent strip specific gravity is based on what constant

pKa of polyelectrolyte in an alkaline medium

indicator of specific gravity reagent strip

Bromothymol blue
1 (blue-alkaline)—> green —> 1.030 (yellow-acid)

Why does urine smell after being left out

breakdown of urea into ammonia

Odor use in the lab

seldom used in routine analysis

Bacterial infections urine odor

strong, unpleasant odor similar to ammonia

Diabetic ketones (diabetes mellitus, starvation, vomitting) urine odor

sweet or fruity odor, if maple syrup smell- serious metabolic defect (Maple syrup urine disease)

Phenylketonuria urine odor

mousy odor

Tyrosinemia urine odor

rancid odor

Isovaleric acidemia urine odor

sweaty feet odor