AUBF-lec W4 Physical Examination of Urine

Physical Examination

Definition:The initial examination performed on urine to assess its color, clarity, odor, and taste.

Specimen Evaluation

Definition:The process of checking the label of the urine specimen for internal and external contamination, requested tests, and transportation delay.

Chemical Examination

Definition:The examination of urine to detect the presence of specific chemicals or substances, such as blood or urobilinogen.

Sediment Examination

Definition:The microscopic examination of the sediment in urine to identify and confirm the presence of certain substances, such as blood cells or crystals.

Urine Color

Definition:The visual indicator of the degree of hydration and the presence of certain disease processes, which can range from colorless (straw) to deep yellow.

Urochrome

Definition:The major pigment responsible for the yellow color of urine, produced by the body during metabolic processes.

Uroerythrin

Definition:A pinkish pigment that can be seen in the sediment of urine and is formed at acidic pH levels.

Urobilin

Definition:A by-product of urobilinogen metabolism that imparts an orange-brown color to urine that is not fresh.

Factors Affecting Urine Color

Definition:The amount of substances present, urine pH, and the structural form of substances can all affect the color of urine.

Normal Urine Color

Definition:The normal range of urine color, which varies from colorless (straw) to deep yellow, depending on the amount of pigment present.

Abnormal Urine Color

Definition:Unusual urine colors, such as red, orange, or dark yellow, which can indicate the presence of abnormal pigments or certain diseases.

Laboratory Correlations Urine Color

Definition:The importance of considering other factors, such as diet or medication, and correlating urine color with other laboratory test results to determine its significance.

Differentiation between Urobilin and Bilirubin

Definition:The differentiation between urobilin and bilirubin in urine, based on their foam presence and color changes upon shaking and standing.

Red/Pink/Brown Urine

Definition:Abnormal urine colors caused by the presence of blood or hemolyzed red blood cells, which can vary in color depending on the amount of blood and the pH of the urine.

Hemoglobin oxidation

The process where hemoglobin is converted to methemoglobin, resulting in a brown color.

Glomerular bleeding

Bleeding in the glomerulus, leading to red blood cells in the urine and a reddish-brown color.

Porphyria

A hereditary/genetic disease that causes an increase in porphyrins, leading to changes in urine color and other symptoms.

Menstrual contamination

Presence of menstrual contaminants in urine, which should be noted when interpreting test results.

Highly pigmented foods

Certain foods can contribute to the color pigment of urine, causing changes in urine color.

Medications

Certain medications, such as Rifampin and Phenothiazines, can change the color of urine.

Bacterial infections

Bacterial infections, such as urinary tract infections, can cause urine to appear blue or green.

Indicanuria

A disorder where Indican, a bluish/purplish substance, is present in the urine due to bacterial infections or intestinal disorders.

Medications

Certain medications, including Methocarbamol and Methyldopa, can cause urine to appear blue, green, or darkening.

Methemoglobin

The oxidation product of hemoglobin, resulting in a brown or black color in urine.

Melanin

A water-soluble substance derived from melanocytes in the skin, which can cause urine to appear brown or black.

Alkaptonuria

A rare genetic disorder that causes the production of homogentisic acid, leading to black urine.

Urine volume

The amount of urine excreted by the kidneys, which can be influenced by factors such as fluid intake and hydration status.

Oliguria

Decreased urine output, often associated with dehydration or renal dysfunction.

Anuria

Total absence of urine flow, usually caused by serious kidney damage or decreased blood flow to the kidneys.

Polyuria

Increased urine volume, often caused by excessive fluid intake or underlying medical conditions such as diabetes mellitus or diabetes insipidus.

Diabetes insipidus

Lack of ADH or nonresponsive ADH receptors.

Caffeine and alcohol

Suppressants of antidiuretic hormones, causing polyuria.

Nocturia

Excessive urine output during the night.

Increase in nocturnal excretion of urine

Increase in urine output during the night.

Pregnancy

Associated disorder with nocturia.

Chronic progressive renal failure

Associated disorder with nocturia.

Nocturia

Excessive urine output during the night.

Night-to-day ratio of urine

Normal ratio is 1:2 or 1:3, in nocturia it is 2:1.

Diabetes Mellitus

Increase in glucose causes an increase in specific gravity.

Diabetes Insipidus

No problem with solute concentration, specific gravity decreases due to excessive dilution of urine.

Urine clarity

Describes the overall visual appearance of a urine specimen.

Cloudiness of urine

Caused by suspended particulate matter that scatters light.

Clarity

Refers to the transparency of the urine specimen.

Turbidity

Opposite of clarity, print cannot be seen through urine.

Milky urine

Clotted urine.

Nonpathologic causes of urine turbidity

Squamous epithelial cells, mucus, amorphous phosphates, carbonates, urates, semen, spermatozoa, fecal contamination, radiographic contrast media, talcum powder, vaginal creams.

Pathologic causes of urine turbidity

RBCs, WBCs, bacteria, yeast, nonsquamous epithelial cells, abnormal crystals, lymph fluid, lipids.

Acidic urine

Amorphous urates, radiographic contrast media.

Alkaline urine

Amorphous phosphates, carbonates.

Soluble with heat

Amorphous urates, uric acid crystals.

Insoluble with dilute acetic acid

RBCs.

Soluble in dilute acetic acid

WBCs, bacteria, yeast, spermatozoa.

Soluble in ether

Lipids, lymphatic fluid, chyle.

Specific gravity

Expression of urine concentration in terms of density.

Colligative properties

Freezing point, boiling point, vapor pressure, osmotic pressure.

Osmolality/osmolarity

Measure of the amount of solute present in urine.

Urinometer

Less accurate method for measuring specific gravity, requires a large volume of specimen, calibration and solute corrections needed.

Refractometer

Indirect method for measuring specific gravity, measures refractive index, small volume of specimen needed, no temperature correction required.

Harmonic oscillation densitometry

Most accurate method for measuring specific gravity, based on the principle of sound wave frequency change, no longer used in the lab.

Reagent strip

Rapid test for urine constituents, measures pKa.

Polyelectrolyte

A type of polymer that contains charged groups, which can undergo changes in its properties due to interactions with organic and inorganic substances.

Urine odor

The characteristic smell of urine, which can vary depending on the presence of certain substances or medical conditions.

Aromatic odor

The normal and faint smell typically associated with urine.

Foul, ammonia-like odor

An unpleasant smell caused by bacterial decomposition or urinary tract infection (UTI).

Fruity, sweet odor

A smell resembling fruit or sweetness, often indicating the presence of ketones, which can be associated with diabetes mellitus, starvation, or vomiting.

Maple syrup odor

A distinctive smell resembling maple syrup, often associated with Maple Syrup Urine Disease, a metabolic disorder.

Mousy odor

A smell similar to that of a mouse, often indicating the presence of phenylketonuria, an inborn error of metabolism.

Rancid odor

A strong and unpleasant smell, often associated with tyrosinemia, another metabolic disorder.

Sweaty feet odor

A smell resembling sweaty feet, often indicating the presence of isovaleric acidemia, a metabolic disorder.

Cabbage odor

A smell resembling cabbage, often associated with methionine malabsorption, a metabolic disorder.

Bleach odor

A smell resembling bleach, usually caused by contamination rather than a medical condition.

Droplet transmission

The spread of certain organisms through small droplets, which is why urine odor is no longer assessed in the lab as a precautionary measure.

Bacteria in urine

If an excessive amount of bacteria is found in urine, it can cause a foul or ammoniacal odor, deviating from the normal aromatic odor.

Inborn error of metabolism

A genetic disorder that affects the body's ability to process certain substances, often detected through urine odor and aminoaciduria.

Aminoaciduria

The presence of amino acids in urine, often associated with various metabolic disorders, including phenylketonuria, tyrosinemia, isovaleric acidemia, and methionine malabsorption.