Quiz 2: Iron Flashcards
What part of hemoglobin binds oxygen?
Heme group
Each hemoglobin can bind to how many O2 molecules?
4
Iron deficiency is called?
Anemia
Iron overload is called?
Hemochromatosis
What is the most common cause of anemia in infants, children, and premenopausal women?
Iron deficiency
Iron studies are usually performed after what test?
Abnormal CBC
What two terms are used to describe the typical iron deficient anemia?
Microcytic and hypochromic
Should you rely on serum iron alone?
Nope, iron levels can vary due to time of day
When are iron levels usually higher?
Morning
How does stress impact iron levels?
Decrease iron levels
What medications can alter iron levels?
antibiotics, hormones, hypertension medications, cholesterol medications, deferoxamine
What does deferoxamine do?
Removes excess iron from the body
What conditions are associated with increased iron levels?
Beta-thalassemia, alcoholic cirrhosis, high iron intake, hereditary hemochromatosis
What is the mechanism of iron impact in alcoholic cirrhosis?
Ferritin, the storage form of iron, is stored in liver. When liver is damaged, iron is released to circulation.
What is the mechanism of iron impact in hereditary hemochromatosis?
HFE gene, impaired iron detection and regulation
What are the various CATEGORIES for decreased iron levels?
iron deficiency anemia, renal disease, inadequate absorption, increased loss, increased demand
Examples of inadequate absorption that lead to decreased iron levels?
antacid use, competition with other metals, bowel resection, celiac disease, inflammatory bowel disease
Examples of increased loss that lead to decreased iron levels?
From GI tract, nose with severe epistaxis, menstruation, cancer, trauma, phlebotomy
Examples of increased demand that lead to decreased iron levels?
Pregnancy
What does ferritin do?
Serves as the storage unit for iron and responds to the increased iron needs of the body by releasing it when needed
What is the shape of ferritin?
A hollow sphere with iron stored inside
The iron inside ferritin is stored as?
Fe (III) and is oxidized to Fe (II) which allows its release through the channels of the sphere when demands occur
When is ferritin produced?
When excess dietary iron is absorbed, the body responds by producing more ferritin to facilitate iron storage. Ferritin molecules store thousands of iron atoms within their mineral core.
Which is more valuable: serum iron or ferritin?
Ferritin, it doesn’t fluctuate as much
What percent of the body’s iron is stored within ferritin?
15-20%
Where is ferritin stored?
liver, spleen, skeletal muscles, and bone marrow
What is an acute phase reactant?
Something released under times of stress, infections, or cancer
Is serum ferritin an acute phase reactant?
You bet cha’
What is the gold standard in the diagnosis of iron deficiency anemia?
Serum ferritin
What is serum ferritin helpful in distinguishing?
Iron deficiency anemia (ferritin <10 ng/mL) and anemia of chronic disease (ferritin >10 ng/mL)
What conditions can lead to increased ferritin levels?
hereditary hemochromatosis, excess iron intake/poisoning, chronic hepatitis (ferritin is leaked in circulation), alcholism
What conditions can lead to decreased ferritin levels?
iron deficiency anemia
What is transferrins?
glycoproteins that are responsible for the transport of iron
The daily diet contains how many mg of iron?
10-20 mg
How much iron do we absorb per day?
1-2 mg/day
How much iron do we lose from desquamation of epithelia per day?
1-2 mg iron/day
What is desquamation of epithelia?
Skin peeling
How many iron molecules can transferrin bind?
2 iron molecules
What % of transferrin binding sites are normally filled
33%
Where does transferrin transport iron to and from?
From the site of absorption to almost all tissues of the body
Where is transferrin synthesized?
liver
When does transferrin synthesis increase and decrease?
increases in state of iron deficiency but can decrease in infection
Why does transferrin increase in a state of iron deficiency?
Body is trying to be more productive, get all the iron onto the seats of the bus
Why does transferrin decrease in infection?
prevents transport of iron to bacteria for use
In response to severe or chronic infection/disease, the amount of ferritin?
Increases
Why does ferritin increase in response to severe or chronic infection/disease?
Because it’s an acute phase reactant
What is Total Iron Binding Capacity?
the maximum amount of iron that serum proteins, mainly transferrin, can bind to. TIBC reflects the potential for iron binding if all of the binding sites on transferrin were filled.
How does the Total Iron Binding Capacity test work?
Radioactive iron is incubated with human serum (containing trasnferrin) and the amount of radioactive iron taken up by the transferrin in the serum is measured. The radioactive iron can only bind to iron-binding sites on transferrin that are unoccupied.
What is the typical % of iron-binding sites the radioactive iron can bind to?
66%
In iron deficient states would TIBC be higher or lower?
Increased TIBC
In iron overload states would TIBC be higher or lower?
Decreased TIBC
Conditions with increased TIBC?
iron deficiency anemia, pregnancy, oral contraceptives, viral hepatitis
Conditions with decreased TIBC?
anemia of chronic diseases, hemochromatosis, sideroblastic anemia
What is transferrin saturation?
Measurement of percentage of transferrin binding sites that are ctually bound by iron
An increase in the transferrin saturation represents what?
an increase in iron absorption
Normally, iron occupies what % of the iron binding sites on transferrin?
33%
What is the % saturation calculation?
% transferrin saturation = serum iron/ TIBC
Abnormalities in transferrin saturation: increased
iron overload states, hemochromatosis
Abnormalities in transferrin saturation: decreased
iron deficiency anemia, anemia of chronic disease, chronic infections, malignancy, pregnancy
What is iron deficiency anemia?
a deficiency of iron and resulting anemia that usually results from blood loss, poor vitamin intake, or poor absorption of iron (in small intestine). The body makes more transferrin to compensate.
What are your five anemia tests?
CBC, serum iron, serum ferritin, TIBC, transferrin staturation
Lab results in iron-deficiency anemia:
decreased: MCV, serum iron, serum ferritin, % transferrin saturation. Increased: TIBC
What is anemia of chronic disease?
anemia that occurs in the presence of long-standing chronic disease, such as cancer, kidney disease, or severe autoimmune diseases. Usually results from decreased EPO production in kidneys and production of cytokines during disease. The body produces less transferrin to keep iron away from infections that can use it.
Lab results of anemia of chronic disease?
MCV (normal in beginning and becomes decreased over time), serum iron (decreased), serum ferritin (normal or increased), TIBC (normal or low), % transferrin saturation (decreased)
What’s the big test to tell anemia of chronic disease from iron-deficiency anemia?
serum ferritin
When blood is spun what is the largest component?
plasma @ 55%
What is contained in plasma?
91% water, 7% blood proteins, 2% nutrients, 1% hormones and electrolytes
Three main types of plasma proteins:
albumins, fibrinogen, globulins
What % of plasma proteins is albumin?
50-60%
What is albumin involved in?
maintenance of osmotic pressure, transportation of fatty acids, hormones, drugs, and other substances
What % of plasma proteins is globulin?
36%
What are the three types of globulins?
alpha, beta, and gamma
Where are alpha and beta globulins produced?
liver
What do alpha and beta globulins do?
involved in transportation or act as substrates
Where are gamma globulins produced?
lymphoid tissue
Where is albumin synthesized?
liver
What is the most important regulator of oncotic pressure within the vascular system?
albumin
How is albumin synthesis regulated?
nutrition (protein intake) and illness
Albumin also serves as a transporter for:
hormones, lipids, drugs, and many other substances
What disease can cause albumin to spill into urine?
diabetes, long term high blood pressure
Conditions leading to increased albumin levels?
dehydration
Conditions leading to decreased albumin levels?
liver disease, malabsorption/malnutrition, abnormal loss (renal disease, GI loss, skin loss, severe burns), dilution by IV fluids
Where is prealbumin synthesized?
liver
What does prealbumin do?
functions as a transport protein for thyroxine and vitamin A
Is prealbumin or albumin better at assessing a patient’s nutritional status? Why?
Prealbumin because it has a shorter half life and is more sensitive to rapid changes in nutrition
Prealbumin may not be an accurate assessment of nutrition in patients with:
inflammation, infection, or trauma
Prealbumin is increased in what conditions?
pregnancy, Hodkin’s lymphoma
Prealbumin is decreased in what conditions?
renal/liver disease, malabsorption/malnutrition, eating disorders, Crohn’s disease, low protein diet, severe illness/inflammation/infection
Alpha-1-antitrypsin is what type of globulin?
alpha-1-globulin
What is the function of alpha-1-antitrypsin?
to inhibit the action of many key enzymes that are released during inflammatory reactions in the lungs
Deficient or abnormal alpha-1-antitrypsin can lead to?
early onset COPD (damage of lung parenchyma), can also cause liver disease due to toxic accumulation of mutant alpha-1-antitrypsin in the cells of the liver
Conditions leading to decreased/deficient alpha-1-antitrypsin?
COPD (often before age 40), prolonged jaundice or hepatitis in infants, liver dysfunction in children, chronic hepatitis, cirrhosis, hepatocellular carcinoma
Where is haptoglobin produced?
in the liver
What is the function of haptoglobin?
to bind to free hemoglobin when RBCs are destroyed
What happens once haptoglobin is bound to hemoglobin?
it transports hemoglobin back to the liver where the heme is converted to bilirubin
If there is RBC destruction, the haptoglobin becomes?
depleted and its levels decrease
Haptoglobin is very useful when looking for signs of?
hemolytic anemia
Hemolytic anemia can be caused by a variety of factors including:
hereditary abnormalities that cause increased RBC destruction, pathogens, infection, inflammation, and toxins
Conditions resulting in increased haptoglobin
infection, inflammation, neoplastic disease, pregnancy, trauma, acute MI
Conditions resulting in decreased haptoglobin
hemolytic anemia, transfusion reaction, artificial heart valves
Is haptoglobin an acute phase reactant?
Duh
What are complement proteins?
supplement or “complement” the action of antibodies to destroy and eliminate pathogens from the body
The complement pathway involves how many proteins?
9 (C1-9)
Generally, where are complement proteins synthesized?
liver
Which complement proteins are considered acute phase reactants?
C3 and C4
What is the primary function of the complement cascade?
to facilitate oponization of pathogens, making them “tastier” for neutrophils and allow phagocytosis
When does the complement pathway begin?
When the first protein, C1, recognizes the antibody-antigen complex or when certain components of the surface of a bacteria or virus are recognized
What happens to C3?
It’s cleaved, which causes inflammation and opsonization
What is the ultimate goal of the complement pathway?
produce a membrane attack complex (MAC) through this pathway and insert itself into the membrane of the pathogen, causing its lysis and destruction
The most commonly measured complement proteins are?
C3 and C4
Complement levels rise by as much as ?% with many infectious and inflammatory conditions.
50%
Another test used to measure complements is?
CH50
Measurements of complement proteins may be useful in what conditions?
autoimmune diseases, recurrent infections
CH50 is used to measure?
immune processes or screen for reduced complement (frequent infections)
What does CH50 measure?
quantitatively mesaure the ability of human serum to lyse sheep RBCs that have been coated with antibody (when 50% of cells lysed). Measures the amount of hemolysis that occurs.
What must be present for a normal CH50 result?
All nine proteins, C1 through C9
Decreased CH50 indicate?
decreased complement activity
CH50 = zero, indicates?
one of pathway components is totally absent
What are C3 and C4 tests used for?
to investigate the undetectable CH50 level and to monitor some diseases like SLE (lupus), funcgal infections, gram negative septicemia, and shock.
Why are C3 and C4 tests used in response to an overwhelming fungal infection?
Most of us don’t get fungal infections, maybe immunocompromized
Conditions with decreased complement testing (C3,C4) ?
systemic lupus erythematosus, bacterial infections, cirrhosis and hepatitis, malnutrition
Conditions with increased complement testing (C3,C4)?
cancer, ulcerative colitis
What is the most significant gamma globulin?
Immunoglobulins (antibodies)
What produces immunoglobulins?
B lymphocytes
Are immunoglobulins specific or general?
Specific
The type of immunoglobulin is determined by?
variation of the heavy chain
What are the different types of immunoglobulins?
IgG, IgE, IgD, IgA, IgM
Where is IgA usually found?
saliva, tears, colostrum, mucus
What is IgA the defender of?
mucosal or epithelial surfaces against pathogens and allows for clearance of pathogens by cilia or of toxins in GI tract
IgA deficiency can cause what symptoms?
None or it can cause frequent respiratory infections, inflammation of GI tract, unexplained asthma symptoms
IgD represents ?% of circulating immunoglobulins?
0.25%
IgD is found to activate?
basophils and mast cells
IgD increases with?
chronic infections and multiple infections
IgE is the key factor involved in:
allergic reactions and parasitic infections (Helminth infections)
IgE binds to:
mast cells and this initiates a chain of immune responses
What does Immunocap do?
It’s an allergy test which determines specific IgE antibodies against allergens
What is the major antibody produced when an antigen is encountered?
IgG
What is the most prevalent antibody in serum?
IgG
Which antibody has the longest half life?
IgG
The half life of IgG is?
23 days
What is an example of an illness where IgG could persist and be detected for life in some cases?
Mononucleosis
Which antibody can cross the placenta?
IgG, so that the fetus can be protected from infection
What is the initial antibody secreted after an immune challenge with half-life of 10 days?
IgM
IgM antibodies indicate?
Recent infection
How to interpret IgG and IgM
IgM shows up first (I get Meds = I’m sick now), IgG comes in later (I already got Germs = I’m over it now)
IgG and IgM levels are usefully for determining if?
someone has an active infection currently or has already had the infection in the past, but may not have realized it
Multiple myeloma represents ?% of all hematologic cancer?
10%
Neoplastic disorder usually causes proliferation of:
IgG and IgA
In multiple myeloma clones of a single structurally-identical antibody multiples rapidly and now becomes labelled the:
M protein (monoclonal proteins)
What is serum protein electrophoresis useful in?
identifying patients with multiple myeloma and other potentially malignant disorders
Serum protein electrophoresis can be done on?
serum or urine
How to interpret a protein electrophoresis:
albumin is the largest component of serum and represents the largest peak-closest to the positive electrode, globulins are smaller proportion (alpha1, alpha2, beta, gamma) think hang-loose with right hand
What’s the biggest a2 component on a serum protein electrophoresis?
haptoglobin
What’s the biggest B1/2 component on a serum protein electrophoresis?
Transferin
What makes up the gamma component on serum protein electrophoresis?
IgM, IgA, IgG
How would a serum protein electrophoresis look in multiple myeloma?
Big spike in gamma called M (monoclonal) protein, which usually occurs in gamma region, but can occur in the alpha-2 or beta range.
Conditions associated with M protein on protein electrophoresis:
multiple myeloma, smouldering myeloma
What does a polyclonal gammopathy look like on an electrophoresis?
broader based peak in the gamma region
What conditions are associated with polyclonal gammopathy?
liver disease (cirrhosis or hepatitis), autoimmune disease, infection (HIV, hepatitis), hematologic disorders or malignancies (Non-Hodgkin’s lymphoma, sickle cell anemia, thalassemia), non-hematologic malignancies
