Physical and Chemical Examination of Urine

Flashcards covering the terminology, clinical significance, and laboratory principles involved in the physical and chemical examination of urine based on MT 317 lecture notes.

Urochrome

The pigment that causes the yellow color of urine, which is a product of endogenous metabolism and is produced at a constant rate.

Uroerythrin

A pink pigment found in refrigerated urine samples resulting from the precipitation of amorphous urates.

Urobilin

An orange-brown pigment found in older urine specimens that is the oxidation product of the normal urinary constituent urobilinogen.

Bilirubin

An abnormal pigment that can produce a dark yellow/amber/orange urine and creates a yellow foam when the specimen is shaken.

Biliverdin

A pigment formed from the photo-oxidation of bilirubin that gives urine a yellow-green color.

Isosthenuric

A term used to describe urine with a specific gravity of $1.010$, which is the same as the plasma filtrate entering the glomerulus.

Hyposthenuric

A term used to describe urine with a specific gravity below $1.010$.

Hypersthenuric

A term used to describe urine with a specific gravity above $1.010$.

Specific Gravity

The density of a solution compared with the density of a similar volume of distilled water ($1.000$) at a similar temperature.

Refractometry

An indirect method of determining specific gravity by measuring the refractive index based on the concentration of dissolved particles.

Urinometry

A direct method for determining specific gravity using a weighted float attached to a scale calibrated to the density of urine.

Harmonic Oscillation Densitometry

A direct method for measuring urine specific gravity that uses sound waves to determine density.

Osmolality

The concentration of a solution expressed as the number of osmoles of solute particles per kilogram of water ($\text{mOsm/kg}$).

Aromatic

The term used to describe the odor of normal, freshly voided urine.

Nocturia

A condition where an individual excretes more than $500\text{\thinspace mL}$ of urine at night.

Polyuria

The excretion of $3\text{\thinspace L}$ or more of urine each day ($>3\text{\thinspace L/day}$).

Oliguria

A decrease in urine excretion to less than $400\text{\thinspace mL/day}$, often caused by water deprivation or excessive fluid loss.

Anuria

The complete lack of urine excretion.

Protein Error of Indicators

The principle used in reagent strip protein tests where indicator dyes release $\text{H}^+$ ions in the presence of protein while the pH is held constant at $3.0$.

Bence Jones Protein

An abnormal protein found in multiple myeloma that precipitates at $40^{\text{o}}\text{C}$ to $60^{\text{o}}\text{C}$ and redissolves at $100^{\text{o}}\text{C}$.

Double Sequential Enzyme Reaction

The principle for reagent strip glucose testing involving glucose oxidase and peroxidase enzymes.

Greiss Reaction

The diazotization reaction of nitrite with an aromatic amine to form a diazonium salt, used for detecting bacteriuria.

Modified Ehrlich Reaction

The core principle for reagent strip urobilinogen testing where $p$-diethylaminobenzaldehyde reacts with urobilinogen in an acid medium.

Hematuria

The presence of an abnormal quantity of red blood cells in the urine, resulting in a cloudy or smoky appearance.

Hemoglobinuria

The presence of hemoglobin in the urine, typically resulting in a clear red specimen.

Myoglobinuria

The presence of myoglobin in the urine, caused by the breakdown of skeletal muscle, resulting in a reddish-brown urine color.