Liver and Pancreatic Tests

Dr. Janet Pierce

SON Building, Rm 2037
Office phone: 588-1663
Office phone: 588-1663
Office hours: 8:30-10:00 Mondays
E-mail address: Jpierce@kumc.edu

Teach 5 weeks of the course
One test (50 question, open book with notes)

Nursing Functions in Laboratory Testing

Expected to use laboratory data into their practice
Determine if results of test need to be reported immediately  or not urgent
Alert others to watch for symptoms to watch for or precautions to take
Abnormal results may require immediate attention and normal results may also have great diagnostic importance to rule out a disease.
Using critical thinking in judging laboratory serum value is essential
Gather information from charts
Transcribing orders & ordering tests
Nurses must be aware of potential problems with administering test
Point-of-Care Testing – Sophisticated wet and dry chemistry systems (automatic analyzers) that can be used outside the traditional centralized laboratory.
Hand held analyzers

Preparation of client for laboratory test

Venous samples errors:

  • Not allowing the antiseptic to dry (too wet)
  • Moisture in collection tube or syringe
  • Prolonged clenching fist or use of tourniquet
  • Too small of gauge needle
  • Use of too much suction on the syringe
  • Vigorous expulsion of blood into collecting tube
  • Vigorous shaking of blood specimen
  • Using the arm in which there is an IV catheter
  • Using the wrong color of tubes

Normal reference values and the variability of test results

  • False positive and negative
  • Specificity – No lab. test is 100% specific because there is always a factor that can effect a false positive reaction.
  • Sensitivity – Test the degree to which a test detects disease without yielding a false-negative diagnosis.

Conventional Measurements Vs SI

  • Conventional most often used ( ml, mg)
  • SI units a form of the metric system called Le Systeme Internationale d’Unites (SI). More common language all over the world

 

Liver Anatomy & Function

Liver is the largest organ in body

Liver functions

  1. Secretion of bile
  2. Metabolism of bilirubin
  3. Vascular and hematologic functions
  4. Metabolism of nutrients (fats, proteins & carbohydrates
  5. Metabolic detoxification
  6. Storage of minerals and vitamins

Bilirubin Excretion & Metabolism

  1.  Bilirubin is the end product of heme degradation. Breakdown of senescent erythrocytes by phagocytic cells (macrophages). Heme oxygenase oxidizes heme to biliverdin
     **Bilirubin gives bile a greenish black color and produces yellow tinge of jaundice
  2. Bilirubin binds to albumin in the plasma and is called unconjugated bilirubin or free bilirubin
  3. Hepatic processing of bilirubin uptake at the sinusoidal membrane of the liver
  4. Liver conjugates bilirubin and makes it water-soluble (conjugation with 1 or 2 molecules of glucuronic acid by bilirubin)
  5. Excretion of the water, soluble, non-toxic bilirubin glucoronides into bile. These glucoronides are deconjugated by bacteria and degraded to colorless urobilingens. The urobilinogens and are largely excreted in the feces.

(Study Table 11-1, pg 261)

Five Bilirubin Lab. Tests

Test #1: Serum bilirubin indirect (prehepatic or free) 0.1-1.0 mg/dL

Test #2: Serum bilirubin direct - (posthepatic or conjugated)
             0 - 0.4 mg/dL

Test #3: Fecal urobilinogen: Most excreted in feces 40-280 mg/day.

Test #4: Urine urobilinogen: Small amount into bloodstream and goes to urine or back to the liver to be excreted (40-280 mg/day)

Test #5: No bilirubin is normally in urine. It can be detected with Isotest tablets in pathologic conditions

Total Bilirubin

Client fast for 8 hrs to prevent interferes due to fat intake
Requires 1 ml of serum and must be protected from bright light because it can be broken down by light.
Includes both types of bilirubin and range is 0.1-1.0 mg/dL
Increases with biliary obstruction

Indirect (unconjug) Bilirubin

Normal value = 0.1 - 1.0 mg/dL

2 ways to have increase BU

  1. Breakdown of RBC’s causing an excess of free bilirubin in bloodstream - Sickle cell disease, hemorrhage, drug toxicity, autoimmune disease, transfusion reaction etc.
  2. Decreased ability of the liver to conjugate the free bilirubin.

Direct (conjugated) Bilirubin

Normal - 0 - 0.4 mg/dL

Normally the BC circulating in the bloodstream is very low because the larger portion is excreted in bile salts into the intestine
Increase in BC  is caused by

  • Heptocellular injury - drugs, pregnancy
  • Hepatic obstruction - Jaundice caused by elevation in BC. Obstruction can be in collecting channels in liver, hepatic ducts or bile duct.

Urine Bilirubin

Normally ** 0.0

Only direct (conjug) bilirubin can cross the glomerulus and it is usually very low and undetectable because it is converted to urobilinogen in the intestine
Used to detect obstruction to the obstructive jaundice
Used as screening for pts know to be exposed to hepatitis

Fecal Urobilinogen

Fecal test usually not taken but may obtain URINE urobilinogen (normal 0-4 mg/24 hr)
Fecal urobilinogen is increased when there is an increased breakdown of RBC (hemolysis) or shunting of portal blood (obstructive jaundice)
Feces are clay-colored when there is a lack of BC in the intestine

Serum Enzymes Changes in Liver Disorders

5 serum enzymes

  1. Alkaline Phosphatase ((ALP)
  2. Gamma-glutamyl Transferase (GGT)
  3. Alamine Amino Transferase (ALT)
  4. Aspartate Amino Transferase (AST)
  5. Lactic Dehydrogenase (LDH)

Alkaline Phosphatase (ALT)

Gamma-glutamyl Transferase (GGT)

Alamine Amino Transferase (ALT)

Aspartate Amino Transferase (AST)

Lactic Dehydrogenase (LDH)

Pancreas

Pancreas is composed of acini and networks of ducts that secrete enzymes and alkaline fluids for digestion.
Pancreatic enzymes hydrolyze proteins, carbohydrates and facts.
Mechanisms by which activation of pancreatic enzymes is initiated by pancreatic duct obstruction, acinar cell injury & defective transport of proenzymes within acinar cells

Pancreatic Enzymes

Serum Amylase

An enzyme that helps digest starch into sugar.
It’s found in high concentrations in the salivary glands and in the PANCREAS.
In acute abdominal pain amylase can be performed as a STAT procedure to differentiate pancreatitis from other acute abdominal problems.

Two isoenzymes for

  1. Salivary
  2. Pancreatic

Pancreatitis is most common reason for increase serum amylase.

 2 most common reasons for pancreatitis are

  1. Gallstones
  2. Alcohol abuse

Elevation begins in 3-6 hrs after inflammation begins
Increase due to:  pancreatitis, obstruction of panc. duct, mumps, acute cholecystitis, intestinal strangulation, mumps, partial gastrectomy, alcoholism, pregnancy, diabetic ketoacidosis (3 due salivary)
Decrease due to: hepatitis, cirrhosis, toxemia of pregnancy, sever burns,

Serum Lipase

Lipase split triglycerides into fatty acids and glycerol. Serum lipase derives primarily from pancreatic lipase which is secreted into the duodenum and participates in fat digestion. If bile is not present, lipase is ineffective.
Lipase rises later in serum than does amylase so it is secondary test for pancreatitis .  Normal value (< 200 U/L)
Morphine, cholinergic drugs and heparin may lead to elevated levels.
Protamine and IV saline may lead to decreased levels.
If patient is ill more than 3 days may be used for acute pancreatitis. Serum amylase levels may return to normal after 3 days but lipase remains elevated for approx. 10 days after onset.
May also be used to diagnose pancreatic carcinoma, severe renal disease , acute cholecystitis.
Decreased may be seen with advanced carcinoma, viral hepatitis and advanced chronic pancreatitis.
Smooth venipuncture with stead blood flow.  Excessive turbulence due to flawed venipuncture can cause hemolysis of erythrocytes and cause inaccurate lipase measure.

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