Laboratory Medicine Flashcards
What are the 5 main electrolytes in body fluid?
Na+, Cl-, Mg2+, Ca2+, K+
What are the 5 functions of hepatocytes?
1) Drug and toxin metabolism
2) Aid digestion via biliary system
3) Protein synthesis and secretion
4) Energy storage (glycogen)
5) Transformation and clearance
How can acetaminophen cause liver necrosis?
Liver produces a toxic metabolite of APAP –> too much leads to necrosis
What is the main job of the liver?
Take insoluble compounds and make soluble for excretion
Pyridoxal phosphate (AKA Vitamin B6) plays a role in what types of reaction in the liver?
It is a coenzyme of all transamination reactions
What is the function of transaminases?
Transfer amine groups to allow for excretion
Is ALT or AST more specific for liver injury and why?
ALT is more specific because found in cytosol of liver - AST is found in both cytosol and mitochondria of liver along with many other organs
What four things cause elevated AST/ALT?
Viral hepatitis, fatty liver (sometimes), toxins (including medications), strenuous exercise
Alk phos tells you about the integrity of what?
Biliary tree
What are the components of total protein?
Albumin and globulin
Bilirubin is a ____________ of older blood cells
Degradation product
Bilirubin buildup can be toxic to which organ?
Brain
What are old red blood cells a source of?
Hemeproteins
What cell breaks down heme to bilirubin?
Macrophages
How is unconjugated bilirubin transported via blood to liver?
It is complexed with albumin
Once bilirubin is uptaken by the liver, what is it conjugated with?
Glucaronic acid
Where is conjugated bilirubin secreted into following the liver?
Into bile then into intestine
What happens to conjugated bilirubin in the intestine? (two steps)
Bacteria remove glnucaronic acid, then bilirubin is converted to urobilinogen
What are the three pathways urobilinogen may take from intestine?
1) Some reabsorbed from gut and enters portal blood where transported to kidney –> excreted in urine as yellow “urobilin”
2) participates in enterohepatic urobilinogen cycle
3) Oxidized by intestinal bacteria to brown stercoblin
In the kidney, urobilinogen is converted to what yellow substance?
Urobilin
If there is elevation in indirect bilirubin, would there be a defect in
a) pre hepatic
b) post hepatic
pathway?
a) pre hepatic
indirect = unconjugated
If there is elevation in direct bilirubin, would there be a defect in
a) pre hepatic
b) post hepatic
pathway?
b) post hepatic
direct = conjugated
Elevations in indirect bilirubin would NOT result from which of the following?
a) Increased production of non-conjugated bilirubin
b) Impaired conjugation of bilirubin
c) Increased hepatic uptake of bilirubin
c) is wrong results from these 3: 1) increased production 2) impaired conjugation 3) impaired hepatic uptake
Would hemolysis result in
a) elevated indirect bilirubin
b) elevated direct bilirubin
a) elevated indirect
- more unconjugated bilirubin present
What is Kernicterus?
Elevation in indirect bilirubin in neonate and infants which leads to severe CNS deficiencies
Crippler/Najjar Syndrome and Gilbert’s Dz both have what in common?
They are caused by problems with enzymatic action that lead to elevation of indirect bilirubin
What would cause accumulation of direct bilirubin?
a) Biliary obstruction
b) Biliary dysregulation
c) Increased secretion of conjugated bilirubin into bile
a) biliary obstruction
Which of the following diseases would NOT be indicated by elevated conjugated bilirubin?
a) Crigler/Najjar Syndrome
b) Gilbert’s Disease
c) Hepatitis
d) Dubin-Johnson Syndrome
e) two of the above
E - A and B
Jaundice is the result of high amounts of ________ being deposited
Bilirubin
True or false: lack of albumin can cause jaundice
True, albumin does not bind bilirubin –> bilirubin not excreted –> jaundice
What is the main agent of intravascular osmotic pressure?
Albumin
How many mg / kg of albumin are produced by a normal adult daily?
150-250 mg / kg
What leads to pitting edema and why?
a) increased albumin
b) decreased albumin
b) decreased albumin
lack of albumin causes water to spill out from interstitial components
How does albumin loss result from severe burns?
Skin is the most important extra storage for albumin
Nephrotic syndrome results in ______uria
Proteinuria
Which of the following would be NOT indicated by decreased albumin?
a) end stage liver disease
b) Celiac disease
c) protein malnutrition
d) acute dehydration
acute dehydration - only clinical thing indicated by increased albumin
Why does Celiac disease contribute to decreased albumin?
If you cannot absorb protein, you cannot make it
What is Kwashiorkor and why does it result in abdominal edema?
This is a disease that happens in a rice-only diet. There is protein malnutrition –> no albumin synthesis –> weak osmotic pressure –> fluid from tissue diffuses into abdomen
What test should be used to evaluate increase or decrease in globulin?
Serum electrophoresis
How many liters of blood does the kidney process daily?
200L
What percentage of daily blood that kidney filters is removed as waste or excess H2O?
1% (2L out of 200)
______ is produced by the kidneys and stimulates RBC production in bone marrow
Erythropoietin
______ is produced by the kidneys and used in regulation of blood pressure?
Renin
The active form of which vitamin is produced by the kidneys?
Vitamin D
Which kidney function test measures GFR (glomerular filtration rate)?
Creatinine
Elevated BUN or creatinine signals what?
Body not excreting efficiently
Blood in urine may signal what in adults? What if they are older?
Adults - kidney infection
Older - bladder ca
Where is brain natriuretic peptide secreted from?
Heart ventricles
Brain natriuretic peptide is secreted in response to what?
Excess stretching of heart ventricles
What does brain natriuretic peptide signal the body to do? (2 pathways)
1) Vasodilation to lower blood pressure –> assist heart
2) Signals kidneys to produce urine –> decrease volume
What is traumatic tap in lumbar punctures?
Blood in CSF due to trauma from actual lumbar puncture not from traumatic brain bleed
Why would estrogen levels be an inappropriate test for menopause?
Estrogen levels fluctuate quite a bit pre and post menopause
What brown substance is produced from urobilinogen in the intestines?
stercoblin
The kidneys produce which vitamin? Is this a protein or hormone?
Vitamin D aka Calcitrol, hormone
