Updated: 3/7/2019

Fat Soluble Vitamins

Topic
Review Topic
0
0
Questions
11
0
0
Evidence
6
0
0
https://upload.medbullets.com/topic/102003/images/vitamin.jpg
Overview 
  • Examples 
    • A
    • D
    • E
    • K
  • Characteristics
    • precursors for coenzymes
    • pancreatic enzymes required for absorption in the ileum
      • malabsorption syndromes can cause fat-soluble vitamin deficiencies 
        • e.g. steatorrhea, cystic fibrosis, and sprue 
    • stored in fat making toxicity possible (unlike water soluble vitamins)
Vitamin A (Retinol)
  • Function 
    • antioxidant
      • neutralize free radicals
    • constituent of visual pigments (retinal)
      • β-carotene from diet enzymatically converted to cis-retinal, which undergoes photoisomerization to trans-retinal when light is absorbed
      • co-factor for protein rhodopsin
    • essential for normal differentiation of epithelial cells into specialized tissue
      • pancreatic and mucus-secreting cells
      • binds intracellular receptors that regulate transcription at the retinoic acid response elements
    • immune system stimulation 
      • stimulates T-cell differentiation and proliferation
      • vitamin A supplementation recommended for measles treatment 
    • retinitis pigmentosa
      • vitamin A supplementation used as a treatment in retinitis pigmentosa (usually autosomal dominant)
  • Source
    • found in liver and green/yellow vegetables
    • β-carotene also a source
      • dimer of retinal that must be cleaved and converted to trans-retinol for intestinal absorption
    • isotretinoin
      • form of retinoic acid used in treatment of acne
  • Deficiency 
    • causes
      • deficiency in dietary intake
        • due to storage in fat must occur over several months
      • malabsorption
      • fat-free diets
    • symptoms
      • night blindness
      • xerophthalmia
      • squamous metaplasia of corneal epithelium
        • spots are known as Bitot spots 
      • follicular hyperkeratosis
        • dry skin due to loss of sebaceous gland function
      • frequent infections
  • Excess
    • causes
      • over supplementation
        • regular intake > 15 x RDA
      • consumption of wild game liver
      • isotretinoin treatment
    • symptoms
      • arthralgias
        • periosteal proliferation
      • alopecia
      • papilledema and seizures
        • result of intracranial swelling
      • skin changes
        • yellow pigment with excess β-carotene but sclera remain white
          • contrasted with jaundice which sclera and skin turn yellow
    • teratogenic
      • cleft palate and cardiac abnormalities
      • a pregnancy test must be done before isotretinoin is prescribed for severe acne
Vitamin D
  • Function
    • raise low blood calcium concentrations
      • ↑ duodenal absorption of calcium and phosphate
      • ↑ reabsorption of calcium from distal renal tubules
      • ↑ bone resorption via activation of osteoclasts
        • bisphosphonates inhibit activation of osteoclasts and ↓ bone resorption
          • e.g., ibandronate, risedronate, and alendronate
    • remodeling of bone
      • osteoblasts have receptors for vitamin D
      • binding stimulates release of alkaline phosphatase (alk-phos)
      • alk-phos dephosphorylates pyrophosphate
        • pyrophosphate normally inhibits bone mineralization
    • matures macrophage stem cells into osteoclasts
  • Source 
    • pre-formed ingestion in diet
      • D2 = ergocalciferol
        • ingested from plants
        • used as pharmacologic agent
      • D3 = cholecalciferol
        • consumed in milk and fish
    • formed in sun-exposed skin 
      • 7-dehydrocholesterol → cholecalciferol (D3) in skin catalyzed by UV light
        • step insufficient in climates where low temperatures do not allow for sun exposure
      • cholecalciferol (D3) → 25-hydroxycholecalciferol (25-OH D3) in liver catalyzed by 25-hydroxylase
        • decrease in hepatic function may result in vitamin D deficiency
          • must supplement with 25-OH D3
        • occurs in the P450 system
      • 25-OH D3→ 1,25-dihydroxycholecalciferol (1,25-(OH)2 D3) in kidney catalyzed by 1α-hydroxylase
        • 1α-hydroxylase upregulated by PTH in response to hypocalcemia
        • decrease in renal function may result in vitamin D deficiency
          • pseudo-vitamin D deficiency rickets
            • hereditary deficiency in 1α-hydroxylase
          • must supplement with 1,25-(OH)2 D3 equivalent
    • 25-OH D3 = storage form
    • 1,25-(OH)2 D3 (calcitriol) = active form
  • Deficiency  
    • causes
      • low sunlight exposures
      • hepatic or renal function decrease
      • fat malabsorption
      • induction of P450 which degrades active vitamin D precursors
    • symptoms
      • rickets in children (bending bones)
      • osteomalacia in adults (soft bones)
      • hypocalcemic tetany
  • Excess
    • causes
      • supplementation > 10x RDA
      • seen in sarcoidosis
        • ↑ activation of vitamin D by epithelioid macrophages
    • symptoms 
      • polyuria, polydipsia, and nocturia
      • hypercalcemia and hypercalciuria
        • high blood calcium concentration promotes metastatic calcification
      • loss of appetite and stupor
      • high levels of vitamin D promote bone resorption
Vitamin E (α-tocopherol)
  • Function
    • antioxidant
    • prevents peroxidation of fatty acids allowing membranes to maintain normal fluidity
    • prevents oxidation of LDL
    • protects against arteriosclerosis
  • Deficiency
    • rare
    • causes
      • fat malabsorption 
        • abetaliproteinemia
    • symptoms
      • ↑ fragility of erythrocytes (hemolytic anemia)
      • muscle weakness
      • neurodysfunction
        • poor joint sensation and ataxia
  • Excess
    • synergistic ↓ in vitamin K dependent clotting factors with warfarin
      • potential hemorrhage in warfarin patients
Vitamin K
  • Function
    • catalyzes γ-carboxylation of glutamic acid residues on blood clotting proteins
      • cofactor for γ-glutamyl carboxylase
      • allows Ca2+ binding site
      • co-translational modification in RER
      • necessary for the synthesis of clotting factors II (prothrombin), VII, IX, X, and protein C and S
    • must be activated by epoxide reductase enzymes
      • inhibited by warfarin, which is a vitamin K antagonist
      • an anticoagulant in vivo (not in vitro)
      • 2-3 days required to achieve anticoagulation
        • heparin given for immediate results
  • Source 
    • normal gut bacterial flora
    • green vegetables
    • breast milk does NOT contain vitamin K 
  • Deficiency 
    • causes
      • fat malabsorption 
      • neonates have sterile intestines and are unable to synthesize vitamin K
        • aggravated by mothers who took anticonvulsants during pregnancy
        • neonates are given vitamin K injection at birth to prevent hemorrhage
      • can also occur after prolonged use of broad-spectrum antibiotics
        • destruction of normal gut flora
      • ↓ in hepatic function can ↓ vitamin K activation
    • symptoms 
      • ↑ PT and normal aPTT, but normal bleeding time (can also see increased aPTT, but as factor VII has the shortest half-life, PT increases before aPTT) 
        • easy bruising and bleeding
        • hemorrhagic disease of the newborn
  • Excess
    • rare
    • symptoms
      • hemolytic anemia and liver damage
 

Please rate topic.

Average 4.8 of 29 Ratings

Thank you for rating! Please vote below and help us build the most advanced adaptive learning platform in medicine

The complexity of this topic is appropriate for?
How important is this topic for board examinations?
How important is this topic for clinical practice?
Questions (11)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Volume  
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Urine  
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2
Calculator

Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK

(M1.BC.1) A 73-year-old male presents to the the clinic with lumbar pain and symmetrical bone pain in his legs and arms. He has trouble going up to his bedroom on the second floor and getting up from a chair. Past medical history reveals that he has had acid reflux for the past 5 years that is refractory to medications (PPIs & H2 antagonists); thus, he had decided to stay away from foods which have previously given him heartburn - red meats, whole milk, salmon - and has eaten a mainly vegetarian diet. Which of the following processes is most likely decreased in this male? Review Topic

QID: 106287
1

Bone mineralization

68%

(13/19)

2

Iron absorption

11%

(2/19)

3

Collagen synthesis

5%

(1/19)

4

Degradation of branched chain amino acids

16%

(3/19)

5

Degradation of hexosaminidase A

0%

(0/19)

M1

Select Answer to see Preferred Response

PREFERRED RESPONSE 1

(M1.BC.22) A 6-month-old boy presents with decreased growth, pigmented retinopathy, hemolytic anemia, and peripheral neuropathy. You suspect that these signs are the result of a vitamin deficiency leading to increased fatty acid oxidation. Which of the following is most likely responsible for this patient's symptoms? Review Topic

QID: 101686
1

Pernicious anemia

14%

(35/245)

2

Abetalipoproteinemia

38%

(94/245)

3

Goat milk ingestion

9%

(23/245)

4

Hartnup disease

13%

(33/245)

5

Excessive boiling of formula

23%

(57/245)

M1

Select Answer to see Preferred Response

PREFERRED RESPONSE 2
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK

(M1.BC.4343) A 37-year-old female presents to her primary care physician with constipation and abdominal pain. She notes that the pain has been present for several days and is not related to food. She also reports increased urinary frequency without incontinence, as well as increased thirst. She takes no medications, but notes taking vitamin supplements daily. Her vital signs are: BP 130/72 mmHg, HR 82 bpm, T 97.0 degrees F, and RR 12 bpm. Lab studies reveal: Na 139, K 4.1, Cl 104, HCO3 25, Cr 0.9, and Ca 12.4. Further studies show an increased ionized calcium, decreased PTH, and increased phosphate. What is the most likely cause of this patient's symptoms? Review Topic

QID: 107035
1

Vitamin deficiency

6%

(12/198)

2

Vitamin overdose

69%

(136/198)

3

Primary endocrine dysfunction

19%

(37/198)

4

Plasma cell neoplasm

5%

(9/198)

5

Inherited disorder

1%

(1/198)

M1

Select Answer to see Preferred Response

PREFERRED RESPONSE 2

(M1.BC.74) A 19-year-old African female refugee has been granted asylum in Stockholm, Sweden and has been living there for the past month. She arrived in Sweden with her 2-month-old infant, whom she exclusively breast feeds. Which of the following deficiencies is the infant most likely to develop? Review Topic

QID: 106608
1

Vitamin A

0%

(0/13)

2

Vitamin B1

23%

(3/13)

3

Vitamin D

62%

(8/13)

4

Vitamin E

0%

(0/13)

5

Vitamin C

15%

(2/13)

M1

Select Answer to see Preferred Response

PREFERRED RESPONSE 3

(M1.BC.6) You are counseling a pregnant woman who plans to breast-feed exclusively regarding her newborn's nutritional requirements. Which vitamins should be given to the newborn? Review Topic

QID: 100071
1

Folic acid

10%

(2/20)

2

Vitamin B6

20%

(4/20)

3

Vitamin K

30%

(6/20)

4

Vitamin D

5%

(1/20)

5

Vitamin K and Vitamin D

35%

(7/20)

M1

Select Answer to see Preferred Response

PREFERRED RESPONSE 5

(M1.BC.66) An eighteen-month-old female recently emigrated from India with her parents. She presents with a macular-papular skin rash and croup. Two days prior to eruption of her skin rash, her pediatrician noted the following small, red, irregularly-shaped spots with blue-white centers on her oral mucosa, shown in Figure A.

You diagnose her with a communicable disease. Which of the following vitamins should supplement her treatment? Review Topic

QID: 100131
FIGURES:
1

Vitamin A

82%

(202/247)

2

Vitamin D

2%

(5/247)

3

Vitamin E

5%

(13/247)

4

Vitamin K

4%

(9/247)

5

Vitamin B6

6%

(15/247)

M1

Select Answer to see Preferred Response

PREFERRED RESPONSE 1
ARTICLES (6)
Topic COMMENTS (24)
Private Note