Chapter 5 - Physical Examination of Urine

Reasons for COLORLESS urine

recent fluid consumption

Reasons for PALE YELLOW urine

Polyuria

Diabetes

Dilute specimen

Reasons for DARK YELLOW urine

Concentrated specimen (white foam)
Bilirubin (yellow foam)

B complex vitamins

Dehydration

Acriflavine

Nitrofurantoin

Reasons for ORANGE-YELLOW urine

Photoxidation of urobilinogen (no foam)

Phenazopyridine (Pyridium) thick orange and yellow foam

Azulfidine

Reasons for ORANGE-BROWN urine

Urobilin

Reasons for YELLOW-GREEN urine

Bilirubin oxidized to Biliverdin

Reasons for GREEN urine

Asparagus*

Pseudomonas infection

IV phenol medications

Clorets

B Vitamins

Reasons for BLUE (and blue-green) urine

Clorets (b-g)

Indican

Familial hypercalcemia (Blue diaper syndrome)

Robaxin

Methylene blue

Reasons for PURPLE urine

catheter bags with Klebsiella and Providencia

Reasons for PINK urine

small amount of RBCs

Uroerythrin (attaches to amorphous phosphates)

Reasons for RED urine

RBCs (cloudy)

Hemoglobin / Myoglobin (clear)

• Hgb = red plasma

• Mgb = clear plasma

Beets

Rifampin 

Menstrual

Black raspberries

Reasons for PORT-WINE urine

Oxidation of porphobilinogen to porphyrias

Reasons for RED-BROWN urine

Myoglobin

RBCs oxidized to Methemoglobin

Reasons for BROWN-BLACK urine

Homogentisic acid (alkaptonuria)

Malignant melanoma

Melanin / melanogen

Fava beans / Rhubarbs / Aloe

Clear urine

No visible particulates, transparent

Hazy urine

Few particulates, print easily seen

Cloudy urine

Many particulates, print blurred through urine

Turbid urine

Print cannot be seen through urine

Milky urine

May precipitate or be clotted

What may cause a white cloudiness in alkaline urine

Amorphous phosphates and carbonates 

What may cause pink brick dust in urine

Amorphous urates due to the presence of uroerythrin 

Causes of nonpathogenic turbidity

Squamous cells, mucus (females)

Bacterial growth in nonpreserved specimens

Refrigerated specimen with precipitated amorphous phosphates (white), carbonates (white), and urates (pink)

Fecal / talc / semen / vaginal creams / IV contrast media contamination

Causes of pathogenic turbidity

RBCs, WBCs, bacteria

Nonsquamous epithelial cells, yeast, trichomonads, abnormal cysts, lymph fluid, lipids

Extent of turbidity should correspond to…

the amount of material observed in the microscopic examination

Specific Gravity definition

the density of a solution compared with the density of an equal volume of distilled water at the same temperature

evaluation of urine concentration

Isosthenuria SG

1.010

SG of plasma ultrafiltrate

Hyposthenuric SG

< 1.010

Hypersthenuric SG

> 1.010

Normal random specimen (urine) range

1.002 - 1.035

most commonly 1.015 - 1.025

< 1.002 may not be urine

Refractometer

measures velocity of light in air vs. velocity of light in solution

Use if SG > 1.040

Uriometry

weighted float attached to a scale that has been calibrated in terms of urine SG

Correcting SG

1 g/dL Protein: SG - 0.003

1 g/dL Glucose: SG - 0.004

Osmolality

More representative measure of renal concentrating ability

affected only by the # of particles present

1 g MW of substance / # of particles into which it dissociates

Ex: NaCl = 58.5 g/som (Na + Cl)

58.5 / 2 = mOsm

Harmonic Oscillation Densitometry

frequency of a sound wave entering a solution changes in proportion to the density of the solution

Reagent strip SG reading

based on pKa

more H+ released, lower pH

blue (1.000) (alkaline) through shades of green, to yellow (1.030) (acid)

Fresh urine smell

faintly aromatic

Foul-ammonia like urine smell

bacterial decomposition

UTI

Fruity, sweet urine smell

Ketones (diabetes mellitus, starvation, vomiting)

Maple syrup urine smell

Maple syrup urine disease

Mousy urine smell

Phenylketonuria

Rancid urine smell

Tyrosinemia

Sweat feet urine smell

Isovaleric acidemia

Cabbage urine smell

Methionine malabsorption  

Bleach urine smell

Contamination