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Lab Interpretation: CBC, RBCs, LFTs, TSH > Liver Function Tests > Flashcards

Liver Function Tests Flashcards

1
Q

Functions of the Liver:

A
  • 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
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2
Q

What are some additional functions of the Liver?

A

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

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3
Q

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

A

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)

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4
Q

What are some guidelines for Hep C screening?

A

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.

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5
Q

What are the best indicators of liver function? Labs?

A

Albumin, Bilirubin, and prothrombin test

AST/ALT will provide more information on liver injury

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6
Q

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

A

Albumin

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7
Q

Albumin is synthesized specifically by the?

A

Liver

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8
Q

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

A

Albumin

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9
Q

What is the half life of albumin?

A

3 weeks

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10
Q

With what conditions do we see low albumin?

A

Malignancy, chronic liver disease

Up to 80% of patients with cirrhosis have normal albumin

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11
Q

When would we see low albumin with normal LFTs?

A
  • Non hepatic causes such as protein loss (proteinuria), acute or chronic inflammatory states, burns, sepsis, trauma, rhuematic disorders, and IV fluids
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12
Q

______results from enzymatic breakdown of heme in the body?

A

Bilirubin

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13
Q

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

A

Total bilirubin

If total bili is elevated ask for a breakdown

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14
Q

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

A

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
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15
Q

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

A

True

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16
Q

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

A

Gilberts Syndrome

Neonatal jaundice

17
Q

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

A

Hepatobiliary disease

Cholestasis/hepatocelluar disease of all types

18
Q

Causes of increased ALT or AST in asympotmatic patients:

A 
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
19
Q

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

A
  • ETOH
  • Hep B
  • Hep C
  • Fatty Liver (NASH)- 2nd most common reason to need liver transplant
20
Q

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

A

AST

21
Q

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

A

True, AST is NOT as specific to liver as ALT

22
Q

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

A

Alcohol, Statin, Tylenol

23
Q

____ is more specific to liver than AST

A

ALT

Half life of 47 hours

24
Q

When ALT is more elevated that AST treatment includes:

A

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

25
Q

What is the approach for asymptomatic elevation?

A
  • 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.
26
Q

What does the Degree of Elevation provide:

A

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
27
Q

What is a normal AST range?

A

0-40

28
Q

What is a normal ALT range?

A

0-40

29
Q

What gives us an AST/ALT ratio?

A

AST/ALT= ratio

30
Q

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

A

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

31
Q

If AST/ALT >1 consider?

A

AST

32
Q

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

A 
True
Should consider: 
Avandia/Actos
Liver infection or disease (NASH/Fatty Liver) 
Toxic agents (Iron)
33
Q

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

A

Fatty Liver

34
Q

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

A

Fatty Liver- typical patient

35
Q

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

A

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

36
Q

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

A

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

37
Q

What is hemochromatosis?

A

Abnormal deposition of iron in the liver, heart and pancreas

38
Q

What lab results are typically seen with hemochromatosis?

A

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

39
Q

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?

A

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

Lab Interpretation: CBC, RBCs, LFTs, TSH (2 decks)

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