Bilirubin and Urinalysis Quiz

Unconjugated bilirubin is water insoluble and cannot pass through the kidney's glomerular barrier, while conjugated bilirubin is water-soluble and can pass into the urine.

The liver conjugates unconjugated bilirubin with glucuronic acid to form water-soluble conjugated bilirubin.

Alkalosis increases the excretion of bilirubin, leading to higher levels of bilirubin appearing in the urine.

<p>It generally indicates an excess of conjugated bilirubin in the bloodstream.</p> Signup and view all the answers

<p>Normal adult urine contains only 0.02 mg of bilirubin per deciliter, which is typically below the detection threshold of standard testing methods.</p> Signup and view all the answers

<p>The nitrite test and the leukocyte esterase test.</p> Signup and view all the answers

<p>When the concentration exceeds $10^5$ to $10^6$ bacteria per mL.</p> Signup and view all the answers

<p>Escherichia coli.</p> Signup and view all the answers

<p>Enterococcus species.</p> Signup and view all the answers

<p>Microscopic urinalysis and bacterial cultures.</p> Signup and view all the answers

<p>A freshly voided sample is preferred because urobilinogen is unstable and can convert to urobilin in acidic urine.</p> Signup and view all the answers

<p>Drug metabolites like phenazopyridine can turn urine orange-red and may mask the reaction with urobilinogen or lead to false positives.</p> Signup and view all the answers

<p>Untreated UTIs can lead to severe kidney damage.</p> Signup and view all the answers

<p>Bilirubin can sometimes cause a green color in the urine, which may interfere with the interpretation of the test results.</p> Signup and view all the answers

<p>High-risk individuals include the elderly, pregnant people, diabetics, and those with a prior history of UTIs.</p> Signup and view all the answers

<p>Bacteria convert urinary nitrate to nitrite in the urine.</p> Signup and view all the answers

<p>A first morning specimen ensures adequate overnight incubation for bacterial growth to convert nitrate to nitrite.</p> Signup and view all the answers

<p>$p$-arsanilic acid is used to form a diazonium salt when reacting with nitrite.</p> Signup and view all the answers

<p>Chemstrip can detect 0.05 mg of nitrite per deciliter, while Multistix can detect 0.075 mg per deciliter.</p> Signup and view all the answers

<p>A pink spot or edge on the strip is interpreted as a negative result.</p> Signup and view all the answers

<p>It typically indicates hemolysis.</p> Signup and view all the answers

<p>Large amounts of urobilinogen are excreted in the urine along with bilirubin.</p> Signup and view all the answers

<p>Jaundiced patients often have dark-colored stools.</p> Signup and view all the answers

<p>Increased urobilinogen levels can occur with fever and dehydration.</p> Signup and view all the answers

<p>Increased urobilinogen levels accompany bleeding into tissues.</p> Signup and view all the answers

<p>Factors such as poorly collected specimens, contaminants, and post-collection bacterial growth can cause a false-positive result.</p> Signup and view all the answers

<p>Medications like phenazopyridine can color urine red, potentially leading to false-positive results.</p> Signup and view all the answers

<p>Urine in an acidic medium can lead to false-positive results in nitrite tests.</p> Signup and view all the answers

<p>Ascorbic acid and urobilinogen are two substances that can lead to false-negative results.</p> Signup and view all the answers

<p>Low pH can contribute to false-negative results by inhibiting the detection of nitrite.</p> Signup and view all the answers

<p>Increased urobilinogen excretion can occur due to hepatocellular damage, exposure to drugs or toxins, cirrhosis, and congestive heart failure.</p> Signup and view all the answers

<p>Urobilinogen output increases in alkaline urine and decreases in acidic urine.</p> Signup and view all the answers

<p>Urobilinogen is referred to in 'units' because it represents a mixture of closely related tetrapyrrole compounds rather than a single measurable substance.</p> Signup and view all the answers

<p>When urobilinogen is oxidized, it becomes urobilins, which are responsible for giving urine its yellow-orange color.</p> Signup and view all the answers

<p>Liver congestion affects urobilinogen handling in conditions such as congestive heart failure.</p> Signup and view all the answers

<p>The diazo test is used to detect bilirubin by forming a blue or purple color when bilirubin is coupled with a reagent.</p> Signup and view all the answers

<p>In the colon, bacteria hydrolyze conjugated bilirubin, resulting in free bilirubin that is then reduced to urobilinogen.</p> Signup and view all the answers

<p>Up to 50% of the urobilinogen is reabsorbed into the portal circulation.</p> Signup and view all the answers

<p>Stercobilins are pigments formed from urobilinogen after further hydrogen removal, contributing to the color of feces.</p> Signup and view all the answers

<p>Conjugated bilirubin is too complex to be absorbed in the small intestine and instead moves to the colon.</p> Signup and view all the answers

<p>It indicates complete obstruction of bile outflow into the intestine.</p> Signup and view all the answers

<p>They can reduce urinary urobilinogen levels by suppressing normal intestinal flora, preventing bilirubin conversion.</p> Signup and view all the answers

<p>Mesobilifuscin is a brown pigment that contributes to urine color and causes dark brown urine when present in excess.</p> Signup and view all the answers

<p>Excess mesobilifuscin can be seen in homozygous β-thalassemia or in the presence of Heinz bodies in erythrocytes.</p> Signup and view all the answers

<p>Tests for blood or bilirubin would not react with mesobilifuscin.</p> Signup and view all the answers

<p>The primary chemical reaction is the Ehrlich aldehyde reaction, which forms a red azo dye from a diazonium compound.</p> Signup and view all the answers

<p>Values from 0.2-1 mg/dL are considered normal.</p> Signup and view all the answers

<p>Porphobilinogen and sulfonamides are two substances that can cause false positives.</p> Signup and view all the answers

<p>The Chemstrip method uses 4-methoxybenzene-diazonium-tetrafluoroborate and can detect levels approximately starting from 0.4 mg/dL.</p> Signup and view all the answers

<p>Like the Multistix method, the Chemstrip method is not specific for urobilinogen and may also detect other reacting compounds.</p> Signup and view all the answers