The Nutritional Anemias Flashcards
What is Hemosiderin?
Intracellular storage form iron. Less abundant than ferritin and haemosiderin appears to be made of degraded ferritin products.
Major difference between ferritin and haemosiderin?
- Haemosiderin is insoluble in water (probably due to lacking the apo-shell)
What is the labile pool?
Refers to iron leaving the plasma and entering the interstitial and intracellular fluid compartments 80-90mg
What is the most metabolically active and smallest iron pool?
Iron bound to Transferrin
1/3 saturated with iron (33%)
Where is Transferrin synthesized?
Apotransferrin is synthesized in the liver.
What is the daily requirements of males both adults and infants?
1mg per day
What is the iron requirement in children (male & female)
.5mg per day
What is the iron requirement for young non-pregnant women?
2mg per day
What is the iron requirement for pregnant women?
3mg per day
What is the daily iron requirement for post menopausal women?
1mg per day
What is the best source of dietary Iron?
Liver
Where is heme iron (iron from meats) absorbed into the body?
Proximal duodenum
How is iron shuttled around inside of duodenal enterocyte?
Bound to ferritin
How is iron transferred from duodenal enterocyte to the circulation?
Via the transporter Ferroportin
How is The Ferroportin transporter regulated?
Via Hepcidin.
Hepcidin is a negative regulator of ferroportin reducing the amount of iron released into the circulation.
What are the functions of Ferroportin?
- Exports iron into the plasma
- Regulates
- Transfer of iron from mother to fetus
- Iron absorption in intestines
- iron export from Macrophages
What are the functions of Hepcidin?
- Negative regulator of iron uptake.
- Binds the iron exporter ferriportin and degrades it
- Inhibits iron flow into plasma from senesent RBCs
- Inhibits duodenal enterocytes engaged in absorption of dietary iron
- Inhibits hepatocytes that store iron
What factors affect the absorption of non-heme (from plant) Iron?
- Reducing agents i.e acids increase non-heme iron absorption
- Chelating agents e.g some found in Turkish clay reduce non-heme iron absorption
- Insoluble iron complexes such as egg yolk, phosphates, phytates, and grains reduce absorption
- Tannic acid tea and calcium all compete for absorption with non-heme iron
What factors outside of the GI tract can increase Iron absorption?
- Hypoxia
- Anemia
- Depletion of Iron stores
- Increased erythropoiesis
What is the incidence of iron deficiency in adults in the US?
- Rare
- Exceedingly rare in men
- More prevalent in infants
What are some of the causes of iron malabsorption?
- Non tropical Sprue (celiac disease)
- GI tract surgery
- Picca
What is non-tropical Sprue?
Gluten induced damage to differentiated villus epithelial cells of the small intestines
Metabolites of Gluten initiate an immunologic reaction against enterocytes.
Results in severe malnutrition, steatorrhea, diarrhea, weight loss, decreased iron absorption.
What is the treatment for Non-Tropical Sprue?
Stop all grains except rice and corn.
What is Tropical Sprue?
Overgrowth of coliforms in the jejunum resulting in the release of enterotoxin that induces fluid secretion which results in malabsorption of folic acid, cobalamin and fat.
What is the treatment for Tropical Sprue?
2 month course of tetracycline and folic acid
What is Pica?
Compulsive eating of unsuitable material such as sand, earth, chalk or coal.
Causes of GI tract bleeding in the U.S
Adult
- Peptic Ulcer Disease
- Hiatal Hernia
- Chronic Gastritis
- Hemorrhoids
- Intermitant bleeding after GI surgery
- Neoplasms of the GI tract
What are the causes of bleeding from the GI tract in Infants?
- Milk Allergy
2. Meckel’s Diverticulum
What are some unusual causes of iron deficiency?
- Respiratory tract bleeding
- Intravascular Hemolysis
- Chronic renal dialysis
- Blood donation
- Facticious bleeding
What is the most common cause of Iron deficiency worldwide?
Hookworm (Ancylostoma duodenale)
Symptoms of Iron Deficiency?
- Asymptomatic
- Fatigue
- Headaches and parathesias
- Irritability
- Decreased exercise tolerance
- Burning tongue
- Picca
Physical findings in Iron Deficiency?
- Pallor
- Glossitis
- Stomatitis
