Lab Assessment Flashcards by Alicia Daum

Changes in the CBC

Anemia
Neutropenia
Thrombocytopenia

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What is the term for a combination of anemia, neutropenia, and thrombocytopenia?

Pancytopenia

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GI Reasons for Anemia

Alcoholism
GI blood loss
Nutritional deficiency (B12 & folate)
Alcohol as a direct toxin

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What type of anemia is due to B12, folate, or myelodisplastic syndrome?

Macrocytic

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Why does GI issues cause neutropenia?

Sequestering of WBC’s in the spleen because of portal hypertension

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What is the etiology of portal HTN?

Cirrhosis of the liver

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Why do GI issues cause thrombocytopenia?

Sequestering in the spleen secondary to portal hypertension

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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

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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

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When are enzymes released in the blood stream?

When hepatocytes are injured

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What are the aminotransferases in the serum?

Alanine aminotransferase (ALT)
Aspartate aminotransferase (AST)

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What is AST produced in?

Hepatocyte injuries
Cardiac muscle
Skeletal muscle
Kidney
Brain 
Pancreas
Lungs
Erythrocytes

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Where are the highest elevations of the serum aminotransferases?

Viral hepatitis
Ischemic hepatitis
Toxicity

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What can a rapid decline in serum aminotransferases a sign of?

Recovery

Massive destruction of viable hepatocytes signaling acute liver failure

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Define Alkaline Phosphatase

Group of enzymes that catalyze the hydrolysis of organic phosphate esters at an alkaline pH

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Where is alkaline phosphatase produced?

Liver
Bone
Intestinal tract (sometimes)

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Where else can alkaline phosphates be produced?

Placenta in the 3rd trimester
Growing children’s bones
Metastatic bone CA
MM

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Where is 5’-nucleotidase found?

Liver
Intestine
Brain
Heart
Blood vessels
Endocrine pancreas

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What is suggested when there are elevated AP & 5’ nucleotidase levels?

Obstructive liver disease

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What does Gamma-glutamyl transpeptidase (GGT) play a role in?

Amino acid transport

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What does an elevated GGT & AP level indicate?

Liver disease

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When can GGT be elevated?

Acute liver toxicity

Alcohol binge

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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

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What is bilirubin made from?

Heme metabolism

Other heme proteins

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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