Lab Assessment Flashcards
Changes in the CBC
Anemia
Neutropenia
Thrombocytopenia
What is the term for a combination of anemia, neutropenia, and thrombocytopenia?
Pancytopenia
GI Reasons for Anemia
Alcoholism
GI blood loss
Nutritional deficiency (B12 & folate)
Alcohol as a direct toxin
What type of anemia is due to B12, folate, or myelodisplastic syndrome?
Macrocytic
Why does GI issues cause neutropenia?
Sequestering of WBC’s in the spleen because of portal hypertension
What is the etiology of portal HTN?
Cirrhosis of the liver
Why do GI issues cause thrombocytopenia?
Sequestering in the spleen secondary to portal hypertension
Applications of LFT’s
Screen for the presence of liver disease
Measure efficacy of treatments for liver disease
Monitor progression of liver disease
Reflect the severity of liver disease
Cons of LFT’s
Do not accurately reflect how well the liver is functioning
Abnormal values can be caused by disease unrelated to the liver
May be normal in advanced liver disease
When are enzymes released in the blood stream?
When hepatocytes are injured
What are the aminotransferases in the serum?
Alanine aminotransferase (ALT) Aspartate aminotransferase (AST)
What is AST produced in?
Hepatocyte injuries Cardiac muscle Skeletal muscle Kidney Brain Pancreas Lungs Erythrocytes
Where are the highest elevations of the serum aminotransferases?
Viral hepatitis
Ischemic hepatitis
Toxicity
What can a rapid decline in serum aminotransferases a sign of?
Recovery
Massive destruction of viable hepatocytes signaling acute liver failure
Define Alkaline Phosphatase
Group of enzymes that catalyze the hydrolysis of organic phosphate esters at an alkaline pH
Where is alkaline phosphatase produced?
Liver
Bone
Intestinal tract (sometimes)
Where else can alkaline phosphates be produced?
Placenta in the 3rd trimester
Growing children’s bones
Metastatic bone CA
MM
Where is 5’-nucleotidase found?
Liver Intestine Brain Heart Blood vessels Endocrine pancreas
What is suggested when there are elevated AP & 5’ nucleotidase levels?
Obstructive liver disease
What does Gamma-glutamyl transpeptidase (GGT) play a role in?
Amino acid transport
What does an elevated GGT & AP level indicate?
Liver disease
When can GGT be elevated?
Acute liver toxicity
Alcohol binge
What is elevated bilirubin due to?
Overproduction of bilirubin
Impaired uptake of bilirubin
Impaired conjugation or excretion of bilirubin
Backward leaking from damaged hepatocytes or bile ducts
What is bilirubin made from?
Heme metabolism
Other heme proteins
What does conjugated bilirubin relate to?
Hepatobiliary disease
Why does unconjugated bilirubin not get filtered by the kidneys?
It adheres to the albumin
Normal urobilinogen result on a UA
Negative
What is the cycle of increased ammonia?
Catabolism of colonic bacteria in the GI tract
Enters circulation via portal vein
Intact liver clears ammonia
What can an increased ammonia concentration lead to?
Hepatic encephalopathy
Define Hepatic Encephalopathy
Reversible impairment of neuropsychiatric function associated with impaired hepatic function
What kind of a draw can you get an ammonia level off of?
Arterial draw
What factors can result in inaccurate results?
Fist clenching
Use of a tourniquet
Whether sample was placed on ice or not
What is the most important serum plasma protein?
Albumin
What does the albumin serum level reflect?
Rate of synthesis
Rate of degradation
Volume of distribution
What other disorders can hypoalbuminemia reflect?
Systemic inflammation
Malnutrition
Chronic liver disease
Why is the PT level measured?
So we don’t have to measure each of the clotting factors
As liver disease progresses the PT should?
Increase
What else is usually measured alongside PT?
INR
What is important to obtain amylase & lipase levels?
Correlate elevations of these enzymes with the history and clinical exam of the patient as well as with other studies
Main Source of Amylase
Pancreas
Salivary glands
Kidneys
Reticuloendothelial system
What is the function of amylase?
Cleave starch into smaller polysaccharides
What inhibits the activity of lipases?
Bile acids
What prevents the bile salts from degrading lipase?
Co-lipase
What is the function of lipase?
Hydrolyze triglycerides into glycerol and FFA
What does a stool examination include?
Microscopic exam: RBC's, epithelial cells, WBC's, fat globules Stool culture Ova & Parasites x3 Clostridium difficile toxin Testing for occult blood in the stool
General Stool Analysis
Bulk Color pH Osmolality Microscopic
What can a positive RBC level indicate?
CA
Infection
IBS
What can a positive epithelial cells level indicate?
Irritated GI tract
What can a positive WBC level indicate?
Infection
IBS
How can you detect fecal fat in a stool analysis?
Sudan stain
Increased amounts of fecal fat can indicate what?
Malabsorption
Pancreatitis
Normal Microscopic Stool Analysis
RBCs- none
Epithelial cells- present
Charcot-Leyden crystals- parasitic infections
Neutral fat globules- 0-2+
Color of a Stool Analysis
Brown- normal Clay color- biliary obstruction Tarry- >100 mL blood upper GI tract Red- blood in large intestine, or undigested beets or tomatoes Black- blood
What are we looking for when a fecal analysis is positive for occult blood and WBC’s?
Bacterial etiology
Infectious Diarrhea Etiologies
Viruses
Bacteria (fever)
Parasites
When should we obtain stool cultures?
Immunocompromised patients
Patients with comorbidities
Patients with IBD
Patients with Severe inflammatory diarrhea
When are routine stool cultures test for?
Shigella
Salmonella
Campylobacter
When does C. difficile colitis develop?
Patients treated with antibiotics or hospitalized patients
What is C. difficile also known as?
Pseudomembranous colitis
Treatment of C. difficile
Metronidazole (Flagyl)
Oral vancomycin
Why use oral vancomycin?
So it can be used by the gut
IV Vanco will not work
When should you send a stool sample for ova and parasites?
Persistent diarrhea
Persistent diarrhea following travel to countries with endemic parasites such as Russia, Nepal, or mountainous regions
Persistent diarrhea with exposure to infants in daycare centers
Bloody diarrhea with few or no focal leukocytes
H. pylori Tests
Endoscopic biopsy
Serologic tests
Antigen in stools
Urease breath tests
Antigen in stools represents what
Active infection
What is the urease breathe test based upon?
Hydrolysis of urea by H. pylori to CO2 & ammonia
Use of Carcinoembryonic Antigen (CEA)
Monitoring for persistent, metastatic or recurrent adenocarcinoma of colon after surgery
Determination ofprognosis for patients with colon cancer
What is a CEA level not useful for?
Local recurrence or screening
