AUBF Laboratory: Lesson 4 - Special Chemical Examination of Urine

special chemical examination

it involves the detection of analytes such as ketones, red blood cells, bilirubin, urobilinogen, nitrite, and leukocytes in urine

ketones, red blood cells, bilirubin, urobilinogen, nitrite, leukocyte

what are the 6 parameters of special chemical examination?

commonly requested by physicians

despite while they provide valuable diagnostic information regarding a patient’s condition, these tests are classified as special because they are not?

specific laboratory procedures

tailored to the individual analyte, traditionally, each of these parameters were assessed using?

simpler, efficient; practical, accessible

However, with the advancement of diagnostic tools, the use of urine reagent strips has made the process significantly more? and offering what methods for performing these tests in routine practice?

ketones

products of fat metabolism

acetone, acetoacetic acid, beta-hydroxybutyric acid

what are the three intermediate types of ketones?

carbon dioxide, water molecules

ketones are not normally found in the urine, due to the complete breakdown of fats into?

fats

however, ketones may appear in the urine, when what are consumed as a source of energy in place of carbohydrates?

sodium nitroprusside reaction

The reagent strip test for ketones is based on what principle? also known as the Legal’s test.

acetoacetic acid interacts with sodium nitroprusside in an alkaline environment

in sodium nitroprusside reaction, what factors result in the formation of a purple-colored compound?

acetoacetic acid, beta-hydroxybutyric acid

sodium nitroprusside reaction test is only specific to which ketone intermediate? as oppose to what other intermediate that it does not detect to?

glycine

acetone is only measured if this is present in the reaction, what is it?

40 seconds, acetoacetic acid, 5-10 mg/dL

what is the reading time, specificity, and sensitivity of the ketone strip?

diabetes mellitus, severe starvation, anorexia, fever, lactic acidosis, propanol poisoning

what are the 6 clinical conditions associated with positive ketone results?

red blood cells

in large amounts, what can be observed in urine just by looking at the specimen?

whole (intact), broken down (hemolyzed)

A reddish color in urine may suggest RBC presence, but they may appear either?

hematuria

typically results in a cloudy red urine

hemoglobinuria

gives a clear red appearance in urine

visible color change

because of small number of RBCs, it might not cause any?

microscopic examination

what examination can confirm the presence of intact RBCs?

free hemoglobin, red cell destruction or hemolytic conditions

microscopic examination cannot detect these molecules. which these molecules are caused by?

chemical testing for hemoglobin

For the limitation of the microscopic examination, what is the most reliable method for identifying blood in the urine?

peroxidase-like activity of hemoglobin

The blood reagent strip works based on what principle?

heme portion

The activity of the blood strip enables what portion of both hemoglobin and myoglobin to react with the chemical dye?

tetramethylbenzidine, oxidized form

the chemical dye with in the blood strip is called? and producing a color change due to the what of the dye?

60 seconds, red blood cells, free hemoglobin and myoglobin; 5-20 RBCs/ml or 0.015-0.062 mg/dL of hemoglobin

what is the reading time, specificity, and sensitivity of the blood reagent strip?

yellow (negative) - green or green-blue (positive)

when free hemoglobin or myoglobin is present in the urine, the test pad develops a uniform color change, ranging from?

spotted color patterns

when whole red blood cells are present, they are broken down upon contact with the test pad, releasing hemoglobin locally in the test pad. This leads to a distinct?

hematuria, hemoglobinuria, myoglobinuria

what are the 3 conditions that are clinically significant in blood reagent strip?

kidney stones, tumors, blood-thinning medications, menstrual contamination, glomerular disease, physical injury, intense physical activity

what are the 7 factors that links to the presence of blood in urine (hematuria)?

blood transfusion reactions, severe burns, intense exercise, hemolytic anemia, malaria

what are the 5 factors that links to free hemoglobin in urine (hemoglobinuria)?

muscle injury, seizures, extreme physical exertion, extended unconsciousness, muscle degenerative disease, certain drugs

what are the 6 factors that links to excess myoglobin in urine (myoglobinuria)?

bilirubin

a byproduct of hemoglobin breakdown

unconjugated bilirubin (non water-soluble), conjugated bilirubin (water-soluble)

bilirubin exists in two forms which are?

conjugated bilirubin

Under normal conditions, neither the two forms of bilirubin is present in urine. However, when bilirubin levels in the blood rise or when there is a blockage in its excretion pathway, what form may only appear in urine?

diazo reaction

the reagent strip test for bilirubin is based on what principle?

2,4-dichloroaniline diazonium salt, 2,6-dichlorobenzene-diazonium-tetrafluoroborate; azodye

in an acidic environment, bilirubin reacts with what salts to form a colored compound? which the dye is called an?

30 seconds, conjugated bilirubin, 0.4-0.8 mg/dL of bilirubin

what is the reading time, specificity, and sensitivity of bilirubin reagent strip?

hepatitis, cirrhosis/other liver disease, biliary obstruction

the presence of bilirubin in urine may indicate 3 conditions

urobilinogen

formed from bilirubin, which is produced when the body breaks down old red blood cells

bile

The liver processes bilirubin to create? it is called a fluid essential for digestion.

gallbladder

some bile travels through small ducts directly into the intestines, while the rest is stored in the?

beneficial bacteria

in the intestines, this convert bilirubin into urobilinogen, what is it?

stool, bile production

Most urobilinogen is excreted in the?, but a portion re-enters the bloodstream, returns to the liver, and is reused in?

urobilinogen

a small amount is eliminated in the urine.

blockage preventing bile from reaching the intestines

Low or absent urobilinogen in urine may indicate a?

hemolytic anemia

elevated urobilinogen levels in urine can suggest, an excessive breakdown of red blood cells, resulting in too much bilirubin as seen in?

liver dysfunction

prevents the liver from reprocessing urobilinogen into bile

Ehrlich aldehyde reaction

the urobilinogen test uses what kind of principle

p-dimethylaminobenzaldehyde

in an acidic environment, this reacts with urobilinogen, aided by a color enhancer, to produce a pink to red color?

22- 26 C

The Ehrlich aldehyde test's accuracy improves with higher temperatures, with an optimal testing range of?