28 Disorders of Nutrition Flashcards
Erythropoiesis
Building blocks:
?, ?, ?, ?
Regulation:
?
Erythropoiesis
Building blocks:
Hemoglobin, Iron, Vitamin B12, Folate (B9)
Regulation:
kidney erythropoietin
A higher than normal reticulocytes count may indicate: Anemia due to red blood cells being destroyed earlier than normal (hemolytic anemia) Bleeding. Blood disorder in a fetus or newborn (erythroblastosis fetalis)
Review the metabolism and biological functions of iron
Metabolism:
- ? are responsible for ?.
- Upon absorption, iron circulates around the body bound to the protein ? and is taken up by different tissues for utilisation.
- The ? system, which includes the splenic macrophages, recycles iron from ?.
- Among many other functions, the liver produces the ?.
- ? controls the release of iron from enterocytes and macrophages into the circulation and is regarded as the master regulator of systemic iron metabolism.
Low Demand:
- absorbed iron is stored within the ? in the form of ?
High Demand:
- absorbed ferrous iron is transported across the ? into blood controlled by ? (?), a ferrous iron export protein that modulates how much of the enterocyte iron is absorbed into circulation and made available to the body
- expression is tightly regulated by the hepatic hormone heparin.
Metabolism:
- Duodenal enterocytes are responsible for dietary iron absorption.
- Upon absorption, iron circulates around the body bound to the protein transferrin and is taken up by different tissues for utilisation.
- The reticuloendothelial system, which includes the splenic macrophages, recycles iron from senescent erythrocytes.
- Among many other functions, the liver produces the hormone hepcidin.
- Hepcidin controls the release of iron from enterocytes and macrophages into the circulation and is regarded as the master regulator of systemic iron metabolism.
Low Demand:
- absorbed iron is stored within the enterocyte in the form of ferritin
High Demand:
- absorbed ferrous iron is transported across the basolateral membrane into blood controlled by ferroportin 1 (FPN1), a ferrous iron export protein that modulates how much of the enterocyte iron is absorbed into circulation and made available to the body
- FPN1 expression is tightly regulated by the hepatic hormone hepcidin.
Iron Deficiency Anemia (IDA)
Possible Causes? 3
Increased requirements
- Growth, pregnancy
Limited Supply
- Poor intake (malnutrition)
- Malabsorption
Increased loss:
- Bleeding
- Phlebotomy (hospital acquire anemia)
A phlebotomy is a procedure to remove a specific amount of blood from a vein in your arm.
Clinical presentation of IDA
9
- fatigue
- pallor
- weak
- dizzy
- headaches
- incr. HR & breathing
- poor growth & neurodevelopment
- impaired immune response
- reduced cognitive ability & physical performance
How is iron deficiency anemia (IDA) treated?
1.Oral iron therapy
- nutrients and medications influence bioavailability
- Gastrointestinal tract toxicity
2.Parenteral Iron
- Iron injections are administered either directly into the blood stream through an IV line or into the muscle
- Faster repletion of iron stores
- Allergic reactions
3.Recombinant human erythropoietin
4.Blood transfusion
What are four iron status markers?
- Serum Iron: Lots of variability (not a good marker)
- Serum Ferritin (FER): Long term stores
- Total iron binding capacity (TIBC) : indirect measurement of transferrin
- Transferrin saturation: %= Iron/TIBC x 100
High TIBC means that you have low levels of iron. When there isn’t much iron to attach to, you’ll have a lot of free transferrin in your blood
Low TIBC means that you don’t have very much transferrin available to bind to iron. In other words, you have high iron levels, so most of the transferrin is bound to it, which leaves very little free in your blood.
What is microcytic anemia?
Lack of iron compromises hemoglobin production and leads to reduction in development of new RBC in the bone marrow -> smaller than normal RBCs
Review the metabolism and biological functions of vitamin B12
- ? soluble vitamin
- Structure?
- Sources? 3
- It is coabsorbed with ? in the ? after being extracted by ?
Vitamin B12 (Cobalamin)
- water-soluble vitamin
- Tetrapyrrole rings, central cobalt atom
- Humans lack enzymes to produce Vit B12 so sources include: microbial synthesis // meat // dairy
- It is coabsorbed with intrinsic factor (IF) in the terminal ileum after being extracted by gastric acid
Biological actions of Vitamin B12
- Co-enzyme that carries out its actions with ? for ?, ?, ? and ?
- Label image
- In chronic B12 deficiency, there may be an elevation in ? and/or ?
- In chronic folate deficiency, there is an elevation in ?
- Co-enzyme that carries out its actions with folate for cell growth, DNA synthesis, RBC production, and neurological function
- Label image
- In chronic B12 deficiency, there may be an elevation in homocysteine and/or methylmalonyl CoA
- In chronic folate deficiency, there is an elevation in homocysteine
Review the metabolism and biological functions of vitamin B12
Clinical presentation of B12 Deficiency: 2
1.Neuropsychiatric:
- Developmental delay, hypotonia, cognitive impairment, peripheral neuropathy, gait, irritability, fatigue, weakness
2.Gastrointestinal
- Feeding difficulties, glossitis, decreased appetite
Macrocytic anemia evaluation
What is Macrocytic Anemia
Impaired DNA synthesis leads to increased RBC growth without cell division
Macrocytic anemia is a blood disorder that causes your bone marrow to make abnormally large red blood cells. It’s also a type of vitamin deficiency anemia. This condition happens when you don’t get enough vitamin B12 and/or vitamin B9 (folate).
How is macrocytic anemia evaluated?
Hematology ?
Biochemistry ?
Hematology:
- CBC, peripheral blood smear
- MCV - high
- Reticulocyte count (Low: inadequate RBC production)
Biochemistry:
- Plasma Vit B12
- Plasma homocysteine (secondary test)
- Plasma methylmalonic acid (secondary test)
- Anti-IF/Parietal cell Ab’s
- Liver and thyroid function
- Bone marrow examination
MCV stands for mean corpuscular volume. An MCV blood test measures the average size of your red blood cells.
A complete blood count (CBC) is a blood test used to evaluate your overall health and detect a wide range of disorders, including anemia, infection and leukemia. A complete blood count test measures several components and features of your blood, including: Red blood cells, which carry oxygen
How is Vitamin B12 deficiency treated?
- supplements
- Intramuscular injection
- Lifelong for pernicious anemia and malabsorption patients
Which of the following is incorrect about vitamin B12:
a) Deficiency is associated with microcytic anemia
b) It is a cofactor involved in DNA synthesis
c) Methylmalonic acid and homocysteine are
surrogate markers
d) The human body is unable to synthesize it
e) Lack of intrinsic factor can cause deficiency
Which of the following is incorrect about vitamin B12:
a) Deficiency is associated with microcytic anemia
b) It is a cofactor involved in DNA synthesis
c) Methylmalonic acid and homocysteine are
surrogate markers
d) The human body is unable to synthesize it
e) Lack of intrinsic factor can cause deficiency
Bone remodeling = balance between bone formation (?) and bone resorption (?)
Regulated by:
- 7
Unmineralized matrix (called ?) composed of 4 secreted by ?
Unmineralized matrix eventually undergoes ? and ? involving 3 to form ? or layers in the bone matrix (MINERALIZED MATRIX)
Bone remodeling = balance between bone formation (osteoblasts) and bone resorption (osteoclasts)
Regulated by:
1. Phosphorous
2. Calcium
3. Vitamin D
4. PTH
5. GH
6. Estradiol
7. Thyroid hormones
Unmineralized matrix (called OSTEOID) composed of Collagen, ALP, osteocalcin, chondroitin sulfate secreted by osteoblasts
Unmineralized matrix eventually undergoes calcification and mineralization involving Ca, phosphorous, Mgto form lamellae or layers in the bone matrix
Endocrine regulation of Calcium
What happens when Ca++ in ECF is decreased?
Parathyroid hormones secrete PTH
PTH acts on
- kidney (increase Calcium reabsorption and phosphate excretion)
- Bone (increase Ca++ pumping to ECF and increase bone resorption)
Vitamin D in small intestine increase Ca++ absorption
Clinical presentation of calcium disorders
Hypercalcemia (4)
Hypocalcemia (4)
Hypercalcemia (4)
1. Moans
2. Bones
3. Groans
4. Stones
Hypocalcemia (4)
1. Muscle pain
2. Seizure
3. Tetany
4. Arrythmias
What is the role of PTH
a) Stimulate calcium resorption from bone
b) Stimulate vitamin D absorption from the gut
c) Stimulate synthesis of vitamin D from the
kidney
d) All of the above
e) A & C
What is the role of PTH
a) Stimulate calcium resorption from bone
b) Stimulate vitamin D absorption from the gut
c) Stimulate synthesis of vitamin D from the
kidney
d) All of the above
e) A & C
PTH and Vitamin D form a tightly controlled feedback cycle, PTH being a major stimulator of vitamin D synthesis in the kidney while vitamin D exerts negative feedback on PTH secretion.
