Liver Function Tests

Question 1

Functions of the Liver:

Answer 1

• Production of plasma proteins
• Glucose homeostasis (production occurs significantly at night)
• Lipoprotein synthesis (sex hormones)
• Bile Acid Production- LDL production
• Vitamin B12, A, D, E, K storage

Question 2

What are some additional functions of the Liver?

Answer 2

Detoxification of medications and endogenous substances (50% of drugs metabolized in the liver)

• primarily through CYP450 enzyme
• purpose to take fat soluble medication and convert to water soluble for purposes of renal excretion

Production of clotting factors

Question 3

True/False LFTs are not great indicators of liver functioning?

Answer 3

True, they are better markers of liver injury and abnormalities in bile flow. If your liver is not working it is not going to produce enzymes.
Normal liver enzymes can be present in the setting of liver damage (seen with Hep C, 33% of these patients have normal liver function tests)

Question 4

What are some guidelines for Hep C screening?

Answer 4

1945-1965 should be screened, patients < 60 should be given Hep B, with diabetes they have a 2-4 fold greater risk of Hep B infections, also giving Hep A.

Question 5

What are the best indicators of liver function? Labs?

Answer 5

Albumin, Bilirubin, and prothrombin test

AST/ALT will provide more information on liver injury

Question 6

What serves as an index of liver functioning/synthesis ability?

Answer 6

Albumin

Question 7

Albumin is synthesized specifically by the?

Answer 7

Liver

Question 8

________ is essential for the transportation of endogenous and exogenous substances and drugs?

Answer 8

Albumin

Question 9

What is the half life of albumin?

Answer 9

3 weeks

Question 10

With what conditions do we see low albumin?

Answer 10

Malignancy, chronic liver disease

Up to 80% of patients with cirrhosis have normal albumin

Question 11

When would we see low albumin with normal LFTs?

Answer 11

• Non hepatic causes such as protein loss (proteinuria), acute or chronic inflammatory states, burns, sepsis, trauma, rhuematic disorders, and IV fluids

Question 12

______results from enzymatic breakdown of heme in the body?

Answer 12

Bilirubin

Question 13

Unconjugated (indirect) and conjugated (direct BADghh)=?

Answer 13

Total bilirubin

If total bili is elevated ask for a breakdown

Question 14

______levels do not become elevated until the liver has lost at least 1/2 of its excretory capacity.

Answer 14

Conjugated

• rarely present in the blood in healthy individuals
• when it is elevated there is a marked decrease in the secretion of bile (marked elevation in bilirubin in serum and urine).
• Hepatobiliary disease is very common

Question 15

True/False Is it common to see an elevation in Bilirubin after fasting (12-24 hours)

Answer 15

True

Question 16

With what conditions do we typically see elevated unconjugated (indirect) bili with normal CBC?

Answer 16

Gilberts Syndrome

Neonatal jaundice

Question 17

With what conditions do we see elevated conjugated (direct) bili?

Answer 17

Hepatobiliary disease

Cholestasis/hepatocelluar disease of all types

Question 18

Causes of increased ALT or AST in asympotmatic patients:

Answer 18

A- autoimmune hepatitis 
B- Hep B
C- Hep C
D- Drugs or toxins (too much iron can cause this) 
E- Ethanol 
F- Fatty Liver (Very common cause of elevated liver enzymes) 
G- Growths 
H- Hemodynamic disorders (CHF) 
I- Iron (Copper) 
M- Muscle Injury

Question 19

3/4 of all elevated AST/ALT values are caused by:

Answer 19

• ETOH
• Hep B
• Hep C
• Fatty Liver (NASH)- 2nd most common reason to need liver transplant

Question 20

This enzyme is found within the liver cell, it rises rapidy with hepatic injury, resolves very quickly (half life of 17 hours)

Answer 20

AST

Question 21

True/False AST is not as specific to liver as ALT

Answer 21

True, AST is NOT as specific to liver as ALT

Question 22

What should your differentials be if AST is elevated more than ALT?

Answer 22

Alcohol, Statin, Tylenol

Question 23

____ is more specific to liver than AST

Answer 23

ALT

Half life of 47 hours

Question 24

When ALT is more elevated that AST treatment includes:

Answer 24

Avanndia or actos
LIver infection or diseases- fatty liver
Toxic agents

Question 25

What is the approach for asymptomatic elevation?

Answer 25

- For an individual who is asymptomatic and picked up on screening or monitoring for various medications - Repeat enzymes in next 2 weeks - Avoid ETOH, Acetaminophen, Ibuprofen - 50% of individuals have normal LFT upon repeat - VIP to remember HEP C patients may have fluctuating LFTs and you may be falsely assured.

Question 26

What does the Degree of Elevation provide:

Answer 26

Significant clues as to the etiology of the liver problem. - < 5 times- mild - 5-10 times- moderate - >10 times - >1000 units/L- hepatitis, drugs or toxins, acute biliary obstruction

Question 27

What is a normal AST range?

Answer 27

0-40

Question 28

What is a normal ALT range?

Answer 28

0-40

Question 29

What gives us an AST/ALT ratio?

Answer 29

AST/ALT= ratio

Question 30

If AST/ALT ratio >1 highly suggestive of what?

Answer 30

Alcoholic LIver DIsease, if >2 HIGHLY suggestive of ETOH liver disease

Question 31

If AST/ALT >1 consider?

Answer 31

AST

Question 32

True/False AST/ALT <1 is the most encountered abnormality

Answer 32

``` True Should consider: Avandia/Actos Liver infection or disease (NASH/Fatty Liver) Toxic agents (Iron) ```

Question 33

______is a liver disease thought to be present in 23% of Americans.

Answer 33

Fatty Liver

Question 34

A patient who presents with obesity, HTN, Diabetes, and Hyperlipidemia most likely has:

Answer 34

Fatty Liver- typical patient

Question 35

In Fatty Liver the AST/ALT ratio will typically be what?

Answer 35

Initially <1 Can shift >1, indicative of advanced fibrosis Patients will also have GGT up to 3x Upper Limits of Normal

Question 36

What are some other differentials of AST/ALT <1?

Answer 36

Hep A Igm Hep B sAg ANti Hep C Hemochromatosis-autosomal recessive condition which can be caused by ETOH

Question 37

What is hemochromatosis?

Answer 37

Abnormal deposition of iron in the liver, heart and pancreas

Question 38

What lab results are typically seen with hemochromatosis?

Answer 38

AST/ALT <1 Elevated Ferritin (>300+) Transferrin Saturation Index >45% is highly suggestive of this condition. Need a eval and biopsy.

Question 39

Labratory findings of elevated CK-MM of 500-100,000 units/L, BUN/Creatinine ratio <5 (normal 10), and increased serum uric acid is indicative of what condition?

Answer 39

Rhabdomyolysis CK-MM is the most sensitive test and the degree of elevation correlates with the relative risk of renal failure Also with this condition, creatine phosphate is released from damaged muscle and is converted into creatinine. And uric acid levels can be markedly elevated > 40mg/dl