Term
| What are the main steps in heme catabolism? |
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Definition
RBC Lysed into Heme and globin chains
Heme lysed into Iron and Bilirubin
Iron undergoes enterohepatic circulation and is re-utilized into RBC’s & / Storage
Bilirubin is metabolized in liver to water soluble direct bilirubin and metabolites that are then excreted in feces and urine |
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Term
| What are the main pathophysiologies and associated clinical diseases/symptoms associated with iron and heme |
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Definition
Decreased iron causes iron deficiency anemia
Increased iron causes hemochromatosis
Increased bilirubin causes jaundice (a symptom, not a disease)
Heme metabolic enzyme deficiencies cause various porphyrias (depending on the enzyme) |
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Term
| Explain the causes of iron deficiency anemia |
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Definition
Anemia is a decreased hemoglobin and hematocrit (% of the blood that is made up of red blood cells)
The basic pathophysiology is increase demand and decreased supply [reduced intake or increased loss]
Causes are:
Insufficient iron intake: young children, pregnant women
Excessive iron loss: elderly people with colon cancer (chronic occult blood loss); menstruating women |
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Term
| What are some iron-rich foods? |
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Definition
Grains
Legumes, seeds, soy
vegetables, fruits
meats |
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Term
| What are some signs and symptoms of iron deficiency anemia? |
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Definition
Fatigue
Pallor
Glossitis (red, beefy tongue)
Pica (abnormal craving to eat ice, starch, clay)
Koilonychia (spoon nails - indentation in the nail) |
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Term
| What are some things on a peripheral blood smear that point to iron deficiency anemia? |
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Definition
Microcytes - small and abnormally shaped RBC's
hypochromic RBC - wider central pallor, |
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Term
| How do labs test for iron deficiency anemia? |
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Definition
Hemoglobin ↓, Hematocrit ↓
Peripheral smear shows small pale RBCs
MCV ↓
MCH ↓
MCHC ↓
Serum iron ↓
Ferritin ↓
Iron binding capacity ↑
M = Mean, C= Corpusclar or Cell, H= Hemoglobin |
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Term
| What is a treatment for iron deficiency anemia? |
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Definition
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Term
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Definition
Problems in the breakdown of heme
Heme breakdown – releases bilirubin –transported to liver for excretion – in feces and urine – some undergoes eterohepatic circulaton |
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Term
| Explain prehepatic jaundice |
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Definition
Caused by increased heme breakdown
there is elevated levels of indirect bilirubin
clinical examples - hemolytic anemia, sickle cell anemia |
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Term
| Explain intrahepatic jaundice |
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Definition
Caused by decreased hepatic metabolism
results in elevated levels of both indirect and direct bilirubin (more indirect than direct, ratio depends on specific problem)
clincal examples - hepatitis, liver cirrhosis, liver cancer |
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Term
| Explain posthepatic jaundice |
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Definition
Caused by decreased hepatic excretion
results in elevated levels of direct bilirubin
clinical examples - gall stones, pancreatic cancer, hodgkin's disease |
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Term
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Definition
Yellow discoloration of the skin, sclerae, mucous membranes caused by excessive serum levels of bilirubin
GI Complaints: nausea, vomiting, abdominal pain [RUQ], dark urine, diarrhoea
Caused by
Prehepatic: hemolysis
Intrahepatic: hepatocellular damage (e.g. hepatitis)
Posthepatic: biliary tree obstruction
Physiologic: Newborn |
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Term
| How can labs test for the different types of jaundice? |
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Definition
↑ total bilirubin
Pre- and intra- have ↑ UNconjugated bilirubin (indirect)
Post has ↑ conjugated bilirubin (direct)
Pre- has other labs showing hemolysis: ↑ LDH, ↓ haptoglobin
Intra- has other labs indicating hepatocellular damage: ↑ transaminases (AST, ALT)
Post- has ↑ alkaline phosphatase |
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Term
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Definition
When excess iron accumulates in various body tissues
Mutation of HFE gene is the primary cause
Repeated transfusions (because of thalassemia) is the secondary cause |
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Term
| What are the signs and symptoms of hemochromatosis in different tissues? |
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Definition
Cardiac muscle - Heart failure: shortness of breath enlarged liver, pedal edema
skin - darkened skin
testes - impotence
pancreas - diabetes mellitus: polyuria, polydipsia, polyphagia with weight loss |
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Term
| How do the symptoms of hemochromatosis progress? |
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Definition
"stage 1" (more minor problems) - fatigue, weight loss, weakness
"stage 2" (noticeable serious problems) - arthritis, impotence, early menopause
"stage 3" (life threatening) - diabetes, liver cancer, heart failure |
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Term
| How do labs test for hemochromatosis? |
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Definition
Serum iron ↑
Iron binding capacity ↓
Hyperglycemia |
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Term
| How is hemochromatosis treated? |
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Definition
Phlebotomy
a pint or two of blood is removed
iron decreases and eventually returns to normal
iron will rise again to abnormal levels so blood must be removed each week |
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Term
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Definition
| Group of disorders of heme synthesis caused by enzyme deficiencies which then cause accumulation of porphyrin intermediates |
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Term
| Explain erythropoietic porphyria |
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Definition
Cause: defect in uroporphyrinogen III cosynthetase
Signs/symptoms: hemolysis, photosensitivity
Treatment: avoid sunlight |
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Term
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Definition
Cause: partial deficiency of ferrochetalase
Signs/symptoms: photosensitivity
Treatment: avoid sunlight, beta carotene |
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Term
| Explain the hepatic porphyrias |
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Definition
Acute intermittent
-Partial deficiency of porphobilinogen deaminase
Hereditary coproporphyria
-Partial deficiency of coproporphyrinogen oxidase
Variegate
-Partial deficiency of protoporphyrinogen oxidase
Signs and symptoms
-Abdominal pain
-Seizures
-Psychiatric disturbances
May be precipitated by:
-Ethanol
-Barbiturates
-Fasting
-Infection |
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Term
| How are the hepatic porphyrias treated? |
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Definition
Glucose
Supportive management
Hematin (ferriprotoporphyrin IX) |
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Term
| Explain porphyria cutanea tarda |
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Definition
Cause: partial deficiency of uroporphyrinogen decarboxylase
Signs/symptoms: photosensitivity, skin fragility
Treatment: avoid alcohol, phlebotomy to remove excess iron form damaged liver |
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