Urinalysis and Body Fluids BOC Practice Questions - Physical

A urine sample from a patient with diabetes mellitus will most likely be…

pale yellow with a high specific gravity.

What compound produces a “mousy” odor in urine?

Phenylpyruvic acid.

This is due to the patient’s inability to metabolise phenylalanine, causing the excretion of keto acids in the urine.

This is called phenylketonuria (PKU).

An ammonia-like odor in urine is usually characteristic of…

A bacterial infection. 

Many common UTI pathogens like Proteus produce urease, which breaks down urea into ammonia and produces this characteristic odor. 

Urine that develops a port wine/deep red color after standing may contain…

porphyrins. 

It is indicative of a porphyria, in which hemoglobin is abnormally metabolised. Porophobilinogen (PBG) builds up and is excreted in the urine, then oxidises in air to create the deep red color. 

What collection method would yield the most sterile urine sample?

Suprapubic aspiration.

A urine from a patient with liver disease is reported as having an amber/dark brown color. What compound causes this color?

Bilirubin.

Hepatic damage can lead to the leaking of bilirubin into the bloodstream, where it is then filtered through the kidneys and into the urine.

The clarity of a urine sample should be determined after…

A thorough mixing of the sample.

Bright orange urine from a patient with cystitis is due to the presence of which compound?

Pyridium.

Pyridium is a medication with a bright orange color that is often used to treat bladder infections.

A urine sample that develops a black color after standing most likely contains…

Homogentisic acid. 

Homogentisic acid is found in the urine of patients who are unable to metabolise phenylalanine, leading to the buildup of homogentisic acid in the blood and connective tissues.  

Urine is yellow due to the presence of…

Urochrome.

A patient who suffered a crush injury has urine that appears reddish brown. This is due to the presence of which compound?

Myoglobin. 

When muscle damage occurs, myoglobin can be released from the muscles to the bloodstream, where it is filtered by the kidneys and enters the urine to be excreted.

A random urine is collected after a patient ate lunch. The specimen appears cloudy, and the reagent test strip results were normal. The turbidity of the specimen was likely caused by the presence of…

Amorphous phosphates.

After eating, the stomach releases hydrochloric acid. The increase in acidity is buffered by the release of bicarbonates into the blood. These bicarbonates are consequently filtered through the kidneys and produce more alkaline urine. This phenomenon is known as the alkaline tide. 

In alkaline environments, alkaline crystals like phosphates are more likely to crystallise, leading to increased turbidity. 

In which of the following diseases will urine turn from yellow to brown/black upon standing?

Alkaptonuria.

This is due to the buildup of homogentisic acid (HGA), which turns black in alkaline conditions. 

If testing cannot be performed within one hour of collection, urine samples should be…

Refrigerated at 2 - 8^oC. 

Measurement of specific gravity aids in the evaluation of the kidneys’ ability to…

Concentrate urine. 

Osmolality is the measure of…

The number of dissociated particles in a solution. 

Osmole = molecular weight of a solute / number of ions into which it dissociates into. 

A urine sample has a high SG in the refractometer, but a normal SG when measured by a reagent test strip. Why might this be? 

There are large molecules like proteins and/or glucose present in the sample. 

Refractometers measure refractive index, which can be falsely elevated by the presence of large molecules. 

Reagent test strips measure ionic solutes, so they are not affected by the masses of molecules. 

If a patient with a suspected UTI is alert and ambulatory, what type of urine specimen should be collected?

Midstream clean catch. 

A urine’s specific gravity by reagent test strip is directly proportional to its…

ionic solutes.

Isosthenuria is associated with a specific gravity that is fixed at around…

1.010

What type of urine collection method should be employed to obtain a highly concentrated specimen?

First morning specimen.

A deficiency in ADH (antidiuretic hormone, or arginine vasopressin) is associated with… 

hyposthenuria, or dilute urine with low specific gravity.

When using a refractometer to measure urine concentration, what must be corrected for in the calculation?

The presence of large molecules like glucose and proteins.

For glucose, subtract 0.004 for each 1g/dL. 

For protein, subtract 0.003 for each 1g/dL.

Which collection method would account for diurnal variation when quantitatively measuring urinary analytes?

24 hour timed.

To determine urine concentration after a patient receives radiographic contrast dye, the ideal method is…

Osmometry.

Which urinary parameter can be measured to assess renal tubular function?

Specific gravity.

Refractive index is measured by…

Comparing light velocity in air to light velocity in a solution.

The presence of biliverdin in urine may cause the specimen to appear…

Green.

A urine sample has a sweet odor reminiscent of caramel or burnt sugar. This is associated with which disease?

Maple syrup urine disease.

A random urine specimen from a patient with diabetes insipidus is most likely to appear…

pale yellow.

A patient that produces more than 3L of urine in a 24 hour period is described as having…

polyuria.

A urine sample with a specific gravity of 1.003 will likely appear…

pale yellow or colorless.