Liver Function: Ammonia & Bilirubin Testing

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Questions and Answers

What is the primary purpose of conducting ammonia tests?

To measure blood glucose levels

To evaluate kidney function

To diagnose severe liver diseases (correct)

To screen for diabetes

Which factor is NOT considered when determining normal ranges for laboratory tests?

Overall health status

Age of the individual

Outdoor temperature (correct)

Gender of the individual

What do critical values in laboratory tests indicate?

Normal body function

Slight abnormalities that require monitoring

Results that are not useful for diagnosis

Dangerously abnormal results needing immediate action (correct)

If a patient is on a high-protein diet, what effect could this have on ammonia test results?

Increase in ammonia levels due to protein breakdown Signup and view all the answers

Which specimen is primarily used for chemistry tests?

Blood and urine Signup and view all the answers

Which medication is known to increase blood ammonia levels?

Loop diuretics Signup and view all the answers

What is one reason post-test assessments might be necessary?

To address the implications of abnormal results Signup and view all the answers

Why is it important to understand laboratory terminology?

It is essential for safe and efficient care Signup and view all the answers

Which statement accurately describes the relationship between direct bilirubin and conjugated bilirubin?

Direct bilirubin tends to overestimate actual conjugated bilirubin. Signup and view all the answers

Which condition is NOT typically associated with an increase in blood ammonia levels?

Strenuous exercise before the test Signup and view all the answers

What is the primary source of bilirubin in the serum?

Red blood cell degradation Signup and view all the answers

How does indirect bilirubin correlate with unconjugated bilirubin?

It tends to underestimate levels of unconjugated bilirubin. Signup and view all the answers

Which substance is crucial in the treatment of elevated blood ammonia levels?

Broad spectrum antibiotics Signup and view all the answers

What defines the primary characteristic of Rotor syndrome compared to DJS?

Presence of high urinary coproporphyrin levels Signup and view all the answers

Which symptom is NOT typically associated with primary biliary cirrhosis?

Renal failure Signup and view all the answers

What is a major distinguishing symptom of benign recurrent intrahepatic cholestasis (BRIC)?

Recurrent episodes of intense pruritus Signup and view all the answers

Which organism is commonly associated with AIDS cholangiopathy?

Cryptosporidium parvum Signup and view all the answers

Which treatment is commonly used for Wilson disease?

Copper chelation Signup and view all the answers

What is a possible complication of total parenteral nutrition (TPN)?

Cholestasis Signup and view all the answers

How does benign recurrent intrahepatic cholestasis (BRIC) present in terms of liver damage?

No significant liver damage Signup and view all the answers

In primary biliary cirrhosis, which demographic is most commonly affected?

Females between 30-65 Signup and view all the answers

What percentage of bilirubin production can reach in dyserythropoiesis disorders?

70% Signup and view all the answers

Which of the following is a cause of decreased hepatic clearance of bilirubin?

Congestive heart failure Signup and view all the answers

Which disorder is characterized by defective bilirubin conjugation?

Gilbert syndrome Signup and view all the answers

What is the typical treatment for kernicterus in patients with type I Crigler-Najjar syndrome?

Emergent plasma exchange Signup and view all the answers

Which of the following drugs can inhibit bilirubin uptake in the liver?

Rifampin Signup and view all the answers

What outcome can occur if unconjugated hyperbilirubinemia is left untreated in type I Crigler-Najjar syndrome?

Fatality by age two Signup and view all the answers

What condition is associated with elevated levels of unconjugated bilirubin due to impaired bilirubin conjugation?

Ethinyl estradiol exposure Signup and view all the answers

What is the primary mechanism by which cirrhosis leads to unconjugated hyperbilirubinemia?

Decreased hepatic uptake Signup and view all the answers

Which drug is known to cause isolated elevated bilirubin levels?

Chlorpromazine Signup and view all the answers

What is the predominant conjugated form of bilirubin?

Bilirubin diglucuronide Signup and view all the answers

What distinguishes unconjugated bilirubin from conjugated bilirubin?

Unconjugated bilirubin is water-insoluble. Signup and view all the answers

What happens to conjugated bilirubin after it is excreted into bile?

It is converted into urobilinogens by intestinal bacteria. Signup and view all the answers

Which medical condition can lead to unconjugated hyperbilirubinemia?

Hemolysis Signup and view all the answers

What is the typical volume of plasma required for bilirubin testing?

0.5 mL Signup and view all the answers

Which of these is NOT a cause of conjugated hyperbilirubinemia?

Hemolytic anemia Signup and view all the answers

What color do the stool and urine typically turn in the absence of urobilinogens?

Clay and dark Signup and view all the answers

Study Notes

Ammonia (AMM, NH3)

Measures ammonia in blood
Created by protein breakdown
Liver converts ammonia to urea, excreted in urine
Increased ammonia levels indicate liver disease
Blood tube: Green

Bilirubin

Breakdown product of heme catabolism
Measured as direct bilirubin (DBil) and total-value bilirubin (TBil)
Unconjugated bilirubin is water-insoluble and binds to albumin
Liver conjugates bilirubin to water-soluble form
Overproduction or defects in uptake and conjugation can result in unconjugated hyperbilirubinemia
Excreted into bile and delivered to the small intestine
Intestinal bacteria convert bilirubin into urobilinogens
Urobilinogens are reabsorbed by the intestine and circulated back to the liver
Excreted through urine and stool
Bilirubin testing is indicated upon signs of abnormal liver function

Causes of Elevated Bilirubin Levels

Unconjugated hyperbilirubinemia: hemolysis, defects in uptake and conjugation
- Crigler-Najjar syndromes (types I and II)
- Gilbert syndrome
Conjugated hyperbilirubinemia: defects in excretion
- Congestive heart failure
- Cirrhosis
- Liver disease (e.g., hepatitis)
- Liver cancer
- Obstructive biliary defects (e.g., gallstones)
- Drugs (e.g., rifamycin, chlorpromazine)

Other Causes of Conjugated Hyperbilirubinemia

Sepsis
Shock
Hemochromatosis
Wilson disease
Total parenteral nutrition (TPN)
AIDS cholangiopathy
Benign recurrent intrahepatic cholestasis (BRIC)

Bilirubin Testing

0.5 mL plasma (green-top [heparin] tube) or 0.7 mL serum (red-top tube or gold-top 7-mL SST tube) is required

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Description

This quiz covers key concepts related to ammonia and bilirubin testing in assessing liver function. It explores the formation, measurement, and implications of elevated levels of ammonia and bilirubin. Understanding these biomarkers is essential for identifying liver diseases and managing patient care.