Chapter 5 Worksheet
1. State the importance of using established terminology for describing urine color and clarity.
Terms may differ among laboratories. Having a set of terminology ensures that everyone is on
the same page when it comes to describing specimens.
2. Discuss the origin of the following pigments and their effects on urine color: bilirubin, urobilin,
urochrome, uroerythrin.
Normal urine color can vary from pale or light yellow to deep amber or dark yellow and is the
result of the presence of a pigment called urochrome.
3. List appropriate color terms and the substances that can produce the colors and identify those
substances that indicate a pathologic process.
Cloudy or turbid urine may indicate health conditions such as chyluria, pyuria, or phosphate
crystals. However, other factors can also be influenced, such as vaginal discharge, sperm or
prostatic secretions.
4. List appropriate clarity terms, their definitions and the substances that can cause clarity changes
and identify those substances that indicate a pathologic process.
Cloudiness or an unusual odor can indicate a problem, such as an infection. Protein in urine can
make it appear foamy. Blood in the urine can make it look red or brown. Urine color can be
influenced by what you've just eaten or by certain drugs you're taking.
5. Describe the effects that increased amounts of protein and bilirubin can have on urine foam.
The healthy liver removes bilirubin from your body. However, if your liver is not functioning
properly, the bilirubin can leak into the blood or urine. This may be an indicator of liver disease.
Protein: Low levels of protein in the urine is normal. Elevated protein may reveal that your
kidneys are damaged.
6. Describe the cause of normal urine color, explain conditions that change this urine characteristic
and list any odors associated with each condition.
Normal urine color varies, depending on how much water you drink. Fluids dilute the yellow
pigments in urine, so the more you drink, the clearer your urine looks. When you drink less, the
color becomes more concentrated. Severe dehydration can produce urine the color of amber
7. Identify two variables involved in determining urine concentration.
When water intake is large enough to dilute blood plasma, a urine more dilute than blood
plasma is produced; when water intake is so small that blood plasma is concentrated, a urine
more concentrated than blood plasma is produced.
8. Compare and contrast the specific gravity and osmolality determinations for the measurement
of urine concentration.
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Urine osmolality is an index of the concentration of osmotically active particles, particularly
chloride, sodium, urea, and potassium; glucose can also add significantly to the osmolality when
it is abundant in urine. In a healthy state, the specific gravity of the urine corresponds to the
urine osmolality
State the principle of each of the following specific gravity determination methods: harmonic
oscillation densitometry, reagent strip method, refractometry, urinometer method.
Harmonic oscillation densitometry: the principle is – principle that the frequency of a sound
wave entering a solution changes in proportion to the density of the solution. Advantages are
that temperature corrections are not necessary.
Differentiate between direct and indirect measures of urine specific gravity and compare the
limitations of each method.
The urine specific gravity is commonly used in clinical practice to measure the renal
concentration/dilution ability. Measurement can be performed by three methods: hydrometry,
refractometry and reagent strips.
State the principle of the following osmometry methods: freezing point depression, vapor
pressure depression.
Osmometry is an advanced analytical method for determining the osmotic concentration of
solutions. The osmotic – or solute – concentration of a colloidal system is expressed in osmoles
(Osm) per unit of volume (Osm/L) or weight (Osm/kg).
Describe factors that affect urine volume and the terms used to describe volume variations.
The consumption of certain types of food.
The amount of liquid consumed.
The amount of food consumed.
The amount of fluid lost through breathing and perspiration.
Medical conditions.
Certain medications.
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