Iron Metabolism/Deficiencies Flashcards
About how much iron is in a normal man?
About 3500 mg
If a man loses 1 ml of blood, how much iron does he lose?
1 mg
What is the labile iron pool?
Iron leaving the plasma and entering the interstitial and intracellular fluid compartments (80-90 mg)
How much iron is in transferrin?
3mg (smallest pool)
What does transferrin do?
Carries protein in plasma
How saturated is transferrin with iron?
About 1/3rd
What is the turnover rate of transferrin and where is it synthesized?
10 times; liver
What is the minimal daily iron requirement for an infant? child? young woman? pregnant woman? Man/postmenopausal woman?
1, .5, 2, 3, 1 (x10 for amount that should be ingested daily)
What has the highest nutritional value of iron? Lowers?
Liver; Milk, noodles, rice
What are the 4 factors influencing iron absorption?
1) Iron Stores
2) Rate of Erythropoiesis
3) Hypoxia
4) Inflammation
What 2 things are involved in the regulation of iron uptake?
Ferriportin and Hepcidin
What does ferriportin do?
It is the cellular exporter of iron into the plasma, it regulates the transfer of iron from mother to fetus, the iron absorption in intestines, and export from macrophages
What does hepcidin do?
It is a negative regulator of iron uptake; it binds ferriportin and degrades it. This inhibits iron flow into plasma from recycled RBCs, inhibits duodenal enterocytes engaged in absorption, and inhibits hepatocytes that store iron
What increases the absorption of non-heme iron?
Reducing agents (ascorbic, gastric acid)
What decreases the absorption of non-heme iron?
Insoluble complexes, chelating agents
What are factors outside the GI tract that increase iron absorption?
Hypoxia, Anemia, Depletion of stores, Increase erythropoesis
Is dietary iron deficiency rare in the US?
Yes, in adults and more rare in men
How can infants become iron deficient?
Milk is a poor source
What are the 3 factors leading the the malabsorption of iron?
GI Tract Surgery, Non-tropical Sprue, Picca
What is the GI surgery called used to fix malabsorption?
Billroth surgery
What is non-tropical sprue ?
Cluten induces damage to differentiated villus epithelial cells of small intestine (found in rye, oats, and barley). The metabolites of gluten lead to an immunologic reaction and leads to severe malnutrition
How do you treat non-tropical sprue?
Stop all grains except rice and corn, symptoms will be gone in days to weeks
What is tropical sprue?
Cause is unknown but thought to be an overgrowth of coliforms in jejunum, leads to release of enterotoxin inducing fluid secretion which then leads to malabsorption of folic acid, cobalamin and fat
How do you treat tropical sprue?
2 months of tetracycline and folix acid, B12 if that is deficient too
What is Picca?
Eating laundry starch or clay (Clay is a chelator which binds iron)
What are the 6 causes of GI tract bleeding in US?
1) Peptic Ulcer Disease
2) Hiatal Hernia
3) Chronic Gastritis
4) Hemorrhoids
5) Intermittent bleeding after GI surgery
6) Neoplasms of the GI tract
What are the 2 causes of GI tract bleeding in infants?
1) Milk Allergy
2) Meckels Diverticulum
What are the 5 unusual causes of iron deficiency?
1) Respiratory tract bleeding
2) Intravascular hemolysis
3) Chronic renal dialysis
4) Blood donation
5) Factitious bleeding
How much iron is lost in menstrual bleeding?
20-30 mg/month, x2 in 10% of women
How much iron is lost during delivery?
150-200mg
How much iron is lost during lactation?
30 mg/month
Hookworm (Ancylostoma duodenale) is a cause of what?
Iron deficiency anaemia
What are the symptoms of chlorosis?
Green palor, breathlessness, palpitations, slight ankle edema, GI complaints, emotional disturbance, depression, irritability, moody, “pervasion of appetite”
What are the symptoms of Iron deficiency?
Asymptomatic at first, but then fatigue, headache and parathesias, irritability, decreased exercise tolerance, burning tongue, picca
What are the physical findings of iron deficiency?
Pallor, glossitis, stomatitis, angular chelitis
What is Koilonychia?
From iron deficiency, nails become concave, rigid, and brittle
In a CBC tell whether the following values are low or high (patient with iron deficiency): WBC = 5000/microliters Hmt = 28% MCV = 78 fl RDW = 22% Platelets = 550,000/microliter Retic Count = .2%
Unaffected, low, low, elevated, elevated, very low
In a bar graph showing the total-iron binding capacity, what is the bar split into?
2 Sections, 1 shows unsaturated capacity, the other shows plasma or serum iron
What does increased erythropoetic activity and iron deficiency do to hepcidin?
It suppresses it so more ferriportin is available to increase dietary iron absorption and release iron from stores
Chronic inflammation does what to hepcidin?
Releases cytokines that increase levels of hepcidin, degrades ferriportin which decreases GI uptake and decreased upake from storage
What are the indications for parenternal iron therapy?
Malabsorption, intolerance to oral iron, uncooperative patient, inability to folow instructions
What is Iron Dextran?
Given IM, slowly absorbed and peaks after 10 days; however is painful at site and stains skin
What are benefits/disadvantages of IV iron delivery?
It replenishes iron stores in ours, but leads to thrombophlebitis, arthralgia and fever, hypotension and bradycardia, nasuea and vomiting, or anaphylactic reaction (death)
What are the 5 things to ask if a patient does not respond to iron replacement?
1) Is diagnosis correct?
2) Has bleed been controlled?
3) Has patient been on iron long enough?
4) Has the dose been adequate?
5) Are there factors that would slow a response?
What increases absorption of Iron (digestive)?
HCl, Ascorbic acid
