AUBF LEC: PHYSICAL EXAMINATION OF URINE

fundamental aspect of urinalysis, providing essential preliminary information about a patient's health.

physical examination of urine

physical examination involves assessing the:

• urine’s color

• clarity

• specific gravity

serves as a valuable diagnostic indicator, often prompting patients to seek medical advice when they notice noticeable changes.

urine color

The color of urine is influenced by several factors:

• normal metabolic function

• physical activity

• ingested materials

• pathologic condition

The presence of urochrome, the pigment responsible for the yellow hue, typically ranges from pale yellow to deep amber. This variation is generally a normal result of hydration levels and diet.

Normal Metabolic Functions

Intense physical activity can sometimes lead to darker urine due to increased concentration of metabolic byproducts.

physical activity

Foods, beverages, and medications can significantly alter urine color. For example, beetroot can cause pink urine, while certain medications may turn urine a bright orange.

Ingested Materials

Changes in urine color can also indicate underlying health issues. For example, dark brown or tea-colored urine may suggest liver disease, while red or pink urine could be a sign of hematuria or bleeding within the urinary tract. Black urine may be associated with conditions like alkaptonuria or severe dehydration.

pathologic conditions

Common descriptions of urine color

• pale yellow

• yellow

• dark yellow

primary pigment responsible for the yellow color of urine.

urochrome

urochrome is identified by

Thudichum in 1864

byproduct of endogenous metabolism and is produced at a relatively constant rate under normal conditions. It is a normal component of urine and is produced from the breakdown of hemoglobin in the body.

urochrome

Urochrome Production and Urine Coloration:

1. breakdown of hemoglobin

2. formation of bilirubin

3. conversion to uribilinogen

4. oxidation to urobilin

5. urochrome in urine

journey of urochrome starts with the breakdown of hemoglobin, the oxygen- carrying protein in red blood cells. As red blood cells age and are removed from circulation, hemoglobin is degraded primarily in the liver and spleen. During this process, hemoglobin is converted into a substance called bilirubin.

breakdown of hemoglobin

Once formed, bilirubin is transported to the liver. Here, it undergoes further processing and conjugation, a chemical change that makes it water-soluble. This water-soluble form of bilirubin is then excreted into the bile, which moves from the liver into the intestines.

formation of bilirubin

In the intestines, bilirubin is acted upon by bacteria, which break it down into urobilinogen. Urobilinogen is a precursor to several important substances and can be absorbed into the bloodstream or continue its journey through the intestines.

conversion to urobilinogen

some of the urobilinogen is reabsorbed into the blood stream and transported to the kidneys. In the kidneys, this is done to form urobilin.

oxidation to urobilin

the oxidation process transforms _ into _, which then is excreted in urine

urobilinogen to urobilin

the final product of metabolic pathway, this is the one that gives urine its characteristic yellow color.

urobilin

urobilin is the final product of this metabolic pathway

urochrome in urine

produced through a series of metabolic steps starting with the breakdown of hemoglobin.

urochrome

_ is converted to _, which then forms _ in the intestines.

hemoglobin → bilirubin → urobilinogen

not only contributes to urine coloration but can also offer insights into a person's hydration status and overall health.

pigment/urochrome

The amount of urochrome in urine is influenced by the body’s metabolic state:

• increased production

• storage effects

Conditions such as thyroid disorders or fasting states can lead to

higher production of urochrome (increased production)

Since urochrome is excreted at a constant rate, the intensity of the yellow color in a fresh urine sample can provide a rough estimate of urine concentration:

• dilute urine

• concentrated urine

appears pale yellow

dilute urine

appears dark yellow

concentrated urine

In addition to urochrome, two other pigments contribute to urine color, albeit to a lesser extent:

• uroeryhtrin

• urobilin

An oxidation product of urobilinogen, this pigment imparts an orange-brown color to urine that is not fresh.

urobilin

Dark yellow or amber urine may indicate the presence of this. An abnormal pigment often associated with liver disease or bile duct obstruction.

bilirubin

typically confirmed through chemical tests, it can be suspected if a yellow foam appears when the urine is shaken.

bilirubin

Normal urine produces only a small amount of foam, while a large amount of white foam suggests _

increased protein concentration.

abnormal pigment that results from the breakdown of red blood cells, and its presence in urine is not typical under normal conditions

bilirubin

conditions that can lead to elevated bilirubin levels:

• hepatitis

• cirrhosis

• bile duct obstruction

presence of bilirubin is confirmed with this kind of test

using reagent strips

When urine containing bilirubin is shaken, it may produce a

yellow foam

produced from the oxidation of urobilinogen, a breakdown product of bilirubin. This oxidation process results in a characteristic yellow-orange color in urine.

urobilin

T OR F

The presence of urobilin in urine is a normal occurrence and is part of the typical coloration of urine. It does not indicate any particular pathology

T

presence of this is a normal occurrence and is part of typical coloration of urine, it does not indicate any particular pathology

urobilin

presence of this does not result in foam formation, its color contribution is usually observed as a normal variation in urine color

uroblin

used for urinary tract infections can impart a bright orange hue to the urine. This pigment can obscure the natural color and interfere with chemical tests based on color reactions. It is essential to recognize the presence of such medications to adjust testing procedures accordingly.

phenazopyridine

used to relieve symptoms of urinary tract infections. These drugs can impart a bright orange color to the urine.

phenazopyridine, pyridium, and azo-gantrisin

color caused by phenazopyridine

bright orange

presence of _ should be considered when assessing urine color.

phenazopyridine

common cause of red, pink, or brown urine is the presence of

blood

Red coloration may range from

pink to deep brown

this type of urine can lead to the oxidation of hemoglobin to methemoglobin, causing a brown color.

acidic urine

may suggest glomerular bleeding.

fresh brown urine with blood

Red or brown urine with blood may indicate bleeding in the:

• urinary tract

• kidneys

• bladder

• urethra

characterized by the presence of blood in the urine, can often result in brown-colored urine.

glomerular bleeding

can cause red urine

hemoglobin & myoglobin

Urine with RBCs is typically

red and cloudy

while urine with hemoglobin or myoglobin remains

red and clear

Differentiating between hemoglobinuria and myoglobinuria can be achieved by examining the patient's

plasma

hemoglobinuria will be accompanied by

red plasma

Both hemoglobin (from broken red blood cells) and myoglobin (from muscle breakdown) can cause

red urine

Presence of hemoglobin in the urine, often due to hemolysis or severe bleeding. Urine is red and typically cloudy

hemoglobinuria

Presence of myoglobin in the urine, often due to muscle injury or rhabdomyolysis. Urine is red but remains clear.

myoglobinuria

Differentiating between hemoglobinuria and myoglobinuria is essential for

proper diagnosis and treatment

will be associated with red plasma

hemoglobinuria

will not affect plasma color significantly.

myoglobinuria

Urine containing _ may appear red

porphyrins

resembling the color of port wine. This is due to the oxidation of porphobilinogen.

porphyrins

porphyrins is due to the oxidation of

porphobilinogen

Urine containing porphyrins can appear red due to the oxidation of _.

porphobilinogen

The red color of urine due to porphyrins is often associated with rare metabolic disorders and can help in diagnosing conditions such as

porphyria

red urine can result from ingestion of highly pigmented foods like:

• beets

• blackberries

• certain medications

  • rifampin

  • phenothiazines

Red urine can also be caused by:

• menstrual contamination

• pigmented foods

• medications

Nonpathogenic causes of red urine are generally _ and related to dietary or medication influences.

benign

urine that turns color upon standing may contain melanin, an oxidation product of melanogen associated with malignant melanoma.

brown or black urine

pigment that can cause urine to appear brown or black.

melanin

when this is present in urine, it may darken further upon standing due to oxidation.

melanin

Melanin is produced from

melanogen

melanin presence in urine is often associated with

malignant melanoma

presence of melanin in urine, a rare condition typically indicating this serious underlying disease, such as malignant melanoma

melaninuria

Inborn errors of metabolism such as _ result in the presence of homogentisic acid

alkaptonuria

Inborn errors of metabolism such as alkaptonuria result in the presence of homogentisic acid, imparting a

black color to alkaline urine

metabolic byproduct resulting from the breakdown of tyrosine and phenylalanine.

homogentisic acid

In conditions like _, an inherited metabolic disorder, homogentisic acid accumulates in the body and can cause urine to turn black, particularly when it is alkaline.

alkaptonuria

This condition can lead to darkening of the urine

alkaptonuria

Medications like _ can also produce brown or black urine

• levodopa

• methyldopa

• phenol derivatives

• metronidazole (flagyl)

Used to treat Parkinson’s disease, it can cause urine discoloration due to the drug's metabolic byproducts.

levodopa

An antihypertensive medication that can also cause urine to darken.

methyldopa

Chemicals related to this can result in brown or black urine.

phenol derivatives

An antibiotic that can cause urine to darken.

metronidazole

infections caused by _ can lead to green urine

Pseudomonas aeruginosa

Pseudomonas aeruginosa can lead to green urine due to the production of pigments like _

pyocyanin and pyoverdin

ome intestinal infections can result in increased

urinary indican

Certain medications, including _ can cause urine to turn blue or green

• methocarbamol (robaxin)

• methylene blue

• amitriptyline (elavile)

A muscle relaxant that can cause urine discoloration.

methocarbamol (robaxin)

Used as a dye and for treating methemoglobinemia, it can give urine a blue or green color.

methylene blue

An antidepressant that can cause green urine due to its metabolites.

amitriptyline (elavil)

T OR F

Medication-induced discoloration is generally harmless but can obscure the detection of other abnormalities in urine.

T

Abnormally colored urine in collection bags may indicate

pathological condition or medication presence

these can produce green urine

phenol derivatives in intravenous medication

Purple staining in catheter bags is often due to

indican or bacterial infections

Urine collected in specimen bags can sometimes appear abnormally colored due to various factors:

• phenol derivatives

• purple staining

These can produce green urine and are often used in intravenous medications.

phenol derivatives

In catheter bags, this can be caused by indican or certain bacterial infections, particularly those involving Klebsiella or Providencia species

purple staining