MLAB 1415- Hematology Keri Brophy-Martinez Iron Metabolism and Hypochromic Anemias

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MLAB 1415- Hematology
Keri Brophy-Martinez
Iron Metabolism and Hypochromic
Anemias
Iron Metabolism


Primary function
 Oxygen transport and storage
Distribution
 Types of iron-containing compounds
• Functional, assisting in enzymatic and metabolic
functions
• Transportation or storage
 Location
• RBCs- majority here
• Macrophages of spleen& liver- where destruction of
RBC occurs, liberating iron
• Hepatocytes and enterocytes- storage of iron
Iron Metabolism

Iron absorption and storage is influenced by:





The amount and type of available iron in the diet
• Is it a nutritional deficiency
Incomplete absorption due to GI tract problems
Current iron stores
Increased demand (pregnancy, the growth years)
Excessive loss due to acute or chronic hemorrhage
• menstrual period for women of childbearing years,
GI bleeding for men
Forms of Iron

Nonheme
Ionic or ferric
 Found in vegetables and whole grains


Heme
Found in red meats
 Easily absorbed

Iron Metabolism


Transport
 Transferrin
• Transports iron to bone marrow to be used in hgb
synthesis
• Synthesized in the liver
Storage
 Primarily in the liver
 Ferritin
• Soluble iron, quick release for heme synthesis
 Hemosiderin
• Partially degraded iron, slow release
Iron Balance

Loss of iron
Secretions of urine, bile , sweat and
exfoliation of intestinal epithelial cells
of GI tract
 Approx. 1 mg/ day


Regulation of iron

Delicate balance between loss and
absorption
Laboratory Assessment of
Iron
Serum iron
 Total iron binding capacity (TIBC)
 Percent saturation
 Serum ferritin

Clinical Syndromes of Iron Metabolism

Iron Deficiency Anemia (IDA)
 AKA Sideropenic anemia
 This is the most common form of
anemia.
 IDA occurs when the iron stores
in the body are inadequate to
preserve homeostasis.
Causes of IDA
Dietary
 Blood Loss
 Hemodialysis
 Malabsorption

3 Stages of IDA



Stage 1
• Decrease in storage iron (ferritin decrease)
• No anemia
• RBC morphology normal
• RDW can be elevated
Stage 2
• Decrease in iron for erythropoiesis
• No anemia or hypochromia
• RBC slightly microcytic
Stage 3
• Decrease in Blood Hgb
• Decrease in peripheral tissue oxygen delivery
• All lab tests abnormal
• Microcytic, hypochromic anemia
Clinical Features of IDA






SOB
Lethargy
Pallor
Gastritis
Pica
Koilonychia
IDA: Lab features

Decreased
 RBC, Hgb, Hct, MCV,
MCH, MCHC

Normal to decreased
 Retic

Peripheral blood smear
 microcytichypochromic
 Targets, elliptocytes,
teardrops
 If IDA is caused by
bleeding, leukocytosis
and thrombocytosis are
possible.
IDA: Lab Findings


Bone marrow
 Decrease in stainable iron
 Mild-moderate erythroid hyperplasia
 M:E ratio decreased
Chemistry


Decrease in serum iron and ferritin
Increased TIBC
Anemia of Chronic
Inflammation
Anemia that occurs in patients with
chronic infections, chronic
inflammatory disorders, trauma, organ
failure or neoplasms
 Occurs due to biochemical changes
during inflammation



Hepcidin- acute phase reactant
Hallmark is normal iron stores but low
serum iron
Anemia of Chronic
Inflammation: Lab Features

Typical lab findings

Decreased
• RBC, Hgb, Hct, MCV, MCH, serum iron, transferrin

Increased
• ferritin
 Normal
• MCHC
 Normal to decreased
• Retic, TIBC
 Peripheral blood smear
• normocytic-normochromic
• Targets, elliptocytes, teardrops

Bone marrow
• M:E ratio increased
Anemia’s Associated with
Abnormal Heme Synthesis
Sideroblastic Anemia
 Lead Poisoning
 Porphyrias

Sideroblastic Anemia (SA)

First step in heme synthesis is
affected

Characterized by:
Increase in total body iron
 Presence of ringed sideroblasts in
bone marrow
 Hypochromic anemia

Sideroblastic anemia

Classification


Hereditary
Acquired
• 2 Forms
• Idiopathic
• Secondary type
• Certain therapeutic drugs
• Chronic transfusions (for aplastic anemia,
leukemia, thalassemia)
• Alcoholism and food fads
• Use of iron utensils or increased iron in water
.
Sideroblastic anemia

Mechanism
Adequate iron but it can not be
incorporated into hgb synthesis.
 Iron enters mitochrondria of
metarubricyte, but accumulates
leading to formation of ringed
sideroblasts
 Eventually, mitochrondria rupture

Lead poisoning



Lead interferes with
iron storage in the
mitochondria
Lead damages the
activity of enzymes
used for heme
synthesis
Basophilic stippling
pronounced
Lead Poisoning
Lab features of SA


Peripheral blood
 Pappenheimer bodies
 Hypochromic,
normochromic RBCs
 Normal to increased
platelets
Chemistry
 Increased serum iron,
ferritin
 Decreased TIBC
Hemochromatosis

Condition caused by
increased iron absorption
which deposits in vital organs
such as the liver, spleen and
pancreas which then becomes
fibrotic

Hyperpigmentation of skin

Therapy consists of iron
removal by therapeutic
phlebotomy or chelation
Porphyrias

Excessive production of porphyrins in the bone
marrow (or liver)
 Rare disease caused by accumulation of
porphyrins in developing RBC’s
 Defect in one or more of the enzymes in
heme synthesis pathway
 Characterized by dermal photosensitivity
and rash caused by the sun. The original
werewolf was probably a person with
erythropoietic porphyria.
References
•
•
•
Harmening, D. M. (2009). Clinical Hematology
and Fundamentals of Hemostasis. Philadelphia:
F.A Davis.
McKenzie, S. B., & Williams, J. L. (2010).
Clinical Laboratory Hematology . Upper Saddle
River: Pearson Education, Inc.
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