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PATH 406 > Nutrition: Part 2 > Flashcards

Nutrition: Part 2 Flashcards

1
Q

What are the physiological functions of Vit A? What are the forms? Where is it found?

A

Vit A — 2 forms
- Provitamin A carotenoids: Green leafy vegetables, sweet potatoes, pumpkins and mangoes, and carrots
- Preformed Vit A (retinol): Liver, kidney, egg yolk, butter

Functions:
1. Vision — prevent xerophthalmia and phototransduction
2. Cellular differentiation — embryonic development
3. Regulate growth, immune function and promote healthy skin

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2
Q

What are the physiological functions of Vit E? What are the forms? Where is it found?

A

Alpha-tocopherol: Olive & sunflower oils
- Predominant form in European diet
Gamma-tocopherol: Soybean & corn oil
- Common in American diet

Functions:
1. Antioxidant
2. Promote eosinophilic lung inflammation and airway hyperresponsiveness
3. Inhibit cell proliferation, platelet aggregation and monocyte adhesion

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3
Q

What are the physiological functions of Vit K? What are the forms? Where is it found?

A

2 Forms
1. Vit K1 (Phytomenadione): Leafy green vegetables
2. Vit K2 (Menaquinones): Produced by intestinal bacteria
- K1 is main dietary form
- Circulating Vit K mainly K1
- Hepatic reserves mainly K2

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4
Q

What are the clinical features of Vit A deficiency?

A
  1. Xerophthalmia (dryness, fragility and clouding of cornea
  2. Night blindness
  3. Associated w/ poor bone growth, nonspecific dermatological problems and impaired immune function
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5
Q

What are the clinical features of Vit E deficiency?

A
  1. Hemolytic anemia, thrombocytosis, edema
  2. Progressive spinocerebellar degeneration
  3. Abetalipoproteinemia — rare genetic defects affecting Vit E metabolism or transport
    - Autosomal recessive
    - Mutation in MTTP gene
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6
Q

What are the clinical features of Vit K deficiency? What is the prevention?

A

VKBD - Vit K deficiency bleeding
- Presenting within first 24 hr (early), 2-7 days (normal), 7 days (late)
- Intramuscular injection of 1 mg phytomenadione at birth virtually abolishes the risk of deficiency

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7
Q

What are laboratory investigations needed to investigate Vit A deficiency?

A

CRP

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8
Q

What are laboratory investigations needed to investigate Vit E deficiency?

A

HPLC
1. Alpha-tocopherol
2. Lipid profiles

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9
Q

What are laboratory investigations needed to investigate Vit K deficiency?

A
  1. INR
  2. Plasma phylloquinone
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10
Q

What are the important pre-analytical considerations for vitamins?

A
  1. Fasting
  2. Acute ethanol ingestion may result in increased serum Vit A levels
  3. Light-sensitivity
  4. Vitamin supplements
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11
Q

What is a trace element and what is the difference with a heavy metal? Give examples.

A

Trace elements — group of minerals present in body in trace amounts
- required in the diet in amounts of 100 mg or les per day or present in the body in amounts of 0.01% of body weight or less
- conc. ug/L to ng/L
- Phytates, tannins, oxalate and fibre can bind minerals reducing their absorption

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12
Q

What is the clinical applications of trace element analysis?

A
  1. Monitoring adequacy in high risk patients
    - Malabsorption: GI disease, CF
    - Malnutrition
    - Total parenteral nutrition (TPN)
    - Cancer patients
  2. Disease Screening and Monitoring
    - Cu: Wilson’s disease, Menkes disease
    - Tissue Fe: hemochromatosis
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13
Q

What are the clinical features of Vit A excess? When do they happen?

A

Acute — when single dose of >200 mg of Vit A is ingested
- Elevated intracranial pressure with H/A
- N/V and vertigo
- Blurry vision
- Dry skin
- Hepatotoxicity

Chronic — occurs with long-term ingestion of Vit A doses in amounts higher than 10x the RDA

Teratogenic — during the first trimester of pregnancy, at doses of only several x the RDA
- Birth defect in baby: microcephaly, cardiac anomaly

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14
Q

What are the clinical features of Vit E excess?

A
  • Safe, but in premature infants, high dose Vit E treatment associated with increased risk of sepsis
  • Chronic excessive intake associated w/ increased risk of all cause mortality and prostate cancer
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15
Q

What are the clinical features of Vit K excess?

A

Hemolysis
Liver damage in neonates

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16
Q

How are trace elements classified based on WHO?

A
  1. Essential elements — Fe, Cu, Zn, Se, Cr, I, Molybdenum
  2. Probably essential elements — Mn, Si, Ni, B, V
  3. Potentially toxic elements
    - F, Arsenic, Pb, Mercury, Cadmium, Al, Tin, Lithium
17
Q

What is the function and metabolism of Zn?

A

Function
- Enzyme cofactor
- Forms complex with histidine and cysteine residues called zinc finger
- Regulates cell growth & immune function

Metabolism
- Absorbed in SI
- After absorption, 80% of blood Zn is bound to RBC and 20% in plasma, largely bound to albumin

18
Q

What is the function and metabolism of Cu?

A

Function — essential catalytic cofactor for many enzymes including
1. Cytochrome C oxidase
2. Ceruloplasmin
3. Tyrosinase

Metabolism
- Absorption in GI tract
- Circulates bound to ceruloplasmin, free Cu is toxic
- Elimination of Cu via bile and feces

19
Q

What is the function and metabolism of Se?

A

Function — more than 30 selenoproteins have been identified
1. Glutathione peroxidase: important antioxidant that helps prevent cellular damage from free radicals
2. Iodo-thyronine deiodinase 2: serves as a catalyst for production of thyroid hormone

Metabolism
- Absorbed in duodenum
- Elimination via urine
- Found in seafood, kidney, liver, meat

20
Q

What is the function of Cr?

A

Function — normal insulin function

21
Q

What is the function and metabolism of I?

A

Function — form thyroid hormones
1. T4 - thyroxine
2. T3 - tri-iodotyrosine

Metabolism — found in fish and seafood, drinking water, vegetables
1. Absorbed in proximal small bowel
2. Taken up by thyroid glands
3. Elimination via urine

22
Q

What is the function and metabolism of Mn?

A

Function — found in Mn superoxide dismutase (Mn-SOD)

Metabolism
- Absorption through SI, inhibited by Ca, Ph and fiber
- Absorption is increased in setting of iron deficiency
- Elimination via bile into feces

23
Q

What are the causes and symptoms of Zn deficiency?

A

Causes
- Genetic cause — Acrodermatitis enteropathica
- Inadequate dietary intake or absorption
- Chronic TPN

Symptoms
- Adult: Impaired taste and smell, hair loss, hypogonadism, frequent infections, skin lesion and impaired wound healing
- Children: Loss of appetite, sleep disturbances diarrhea, skin lesion, growth retardation

24
Q

What are the causes and symptoms of Cu deficiency?

A

Acquired deficiency is rare in healthy individuals, causes are:
1. Omission from TPN
2. High intake of Zn
3. Renal dialysis patients
4. Use of Cu chelating agents

Symptoms
1. Hypo-chromic microcytic anemia, can be normocytic/macrocytic
2. Neutropenia
3. Hypopigmentation of hair and skin
4. Structural abnormalities in connective tissue
5. Fetal and neonatal deprivation leads to neurologic dysfunction
6. Neurologic sequelae are usually irreversible

25
Q

What are the causes and symptoms of Se deficiency?

A

Keshan Disease
1. Affected primarily children and women of child-bearing age
2. Due to Se deficiency and infection with virus — when Se deficient, virus becomes more virulent
Symptoms
- Enlarged heart and poor heart function

26
Q

What are the symptoms of Mn deficiency?

A

Poor growth
Decreased fertility
Ataxia
Skeletal deformities
Abnormal fat and carb metabolism

27
Q

What are the causes and symptoms of Cr deficiency?

A

Symptoms
- Impaired glucose tolerance with DM-like symptoms such as elevated blood glucose levels and increased insulin levels
- Elevate blood cholesterol & TG levels

28
Q

What are the causes and symptoms of I deficiency?

A

Causes
- RDA doubles in pregnancy ➔ may develop a relative deficiency if borderline deficient prior to start of pregnancy = fetal hypothyroidism

Symptoms
- CRETINISM
➔ severe iodine deficiency during pregnancy bc fetus is completely dependent on maternal T4 for first 12 weeks of gestation
➔ OR lack of thyroid gland: during the 10th to 12th week of gestation, fetal TSH appears, and the fetal thyroid is capable of concentrating iodine and synthesizing iodothyronines
➔ Lack of thyroxine causes intellectual disability, short stature and myxedema
- GOITER

Treatment ➔ supplementation

29
Q

What are the symptoms of Zn excess?

A
  • Nonspecific GI symptoms: abdominal pain, diarrhea, nausea, vomiting
  • Zn may interfere with Cu absorption, and high Zn intakes can lead to Cu deficiency
30
Q

What are the causes and symptoms of Cu excess?

A
  1. Menkes Disease — rare inherited X-linked recessive disorder of Cu absorption due to mutation in ATP7A
    - Cu accumulates in intestinal cells
    - Symptoms: Presents in infancy, Kinky hair, Seizures, Severe developmental delay, Weakened bones
    - No effective treatment
  2. Wilson Disease — Inborn error of Cu metabolism due to an autosomal recessive mutation in ATP7B ➔ Cu accumulation and toxicity
    - Unable to incorporate Cu into ceruloplasmin or excrete in bile leading to liver accumulation, free Cu is released
    - Deposition of free Cu in organs
    Liver ➔ cirrhosis
    Brain ➔ cognitive, motor behavioural
    Eyes ➔ KF rings
    Kidneys
    Heart
    - Treatment: lifelong chelation treatment with D-penicillamine, Zn supplementation
31
Q

What are the symptoms of Se excess?

A
  1. GI — nausea, emesis, diarrhea
  2. Neurology — mental status changes, visual loss, and peripheral neuropathy
  3. Hair loss, nail changes, tooth decay
32
Q

What are the symptoms of Cr excess?

A
33
Q

What are the symptoms of I excess?

A
34
Q

What are the symptoms of Mn excess?

A

Neurotoxic — affecting primarily extrapyramidal parts of the brain

Symptoms similar to Parkinson’s disease
- Dyscoordination
- Loss of balance
- Confusion

Headache, vomiting and hepatic dysfunction

35
Q

What is the laboratory assessment of Zn?

A
  1. Plasma Zn
  2. Erythrocyte Zn — during acute/chronic inflammation
  3. Albumin
  4. CRP — falsely low albumin in acute phase reaction
36
Q

What is the laboratory assessment of Cu?

A

Excess — Wilson Disease
- 24 hr urine Cu ➔ high
- Serum Cu ➔ low
- Ceruloplasmin ➔ low

Another test
- Tissue Cu

37
Q

What are the considerations for trace metal tests?

A

Preanalytical
1. Trace element collection tube
2. Contamination from air

Technical
1. Unique instrument requires specialized training for running and maintenance

Throughput
1. Run in batches
2. Measurement of multiple elements on same analytical run

38
Q

What may complicate the interpretation of nutritional biomarkers?

A

Acute phase reaction
- Increase/decrease various hepatic plasma protein that carry their nutrients
- Increases permeability of capillaries and transfer certain carrier proteins and nutrients into interstitial space
- Complicates interpretation of nutritional biomarkers: Vit A, albumin, prealbmin, transferrn, Zn, ferritin, Cu

PATH 406 (24 decks)

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