Vitamins Flashcards
What are vitamins
Vitamins are a group of chemically diverse organic compounds that an organism requires for normal metabolism. Apart from a few exceptions (e.g., vitamin D), the human body cannot synthesize vitamins on its own in sufficient amounts and must, therefore, ensure a steady supply through the diet.
What is the difference between fat and water soluble vitamins in terms of storage
Vitamins are classified into fat-soluble vitamins, which the body can store, and water-soluble vitamins, which, with the exception of vitamins B9 (folate) and B12 (cobalamin), the body cannot store over significant periods of time and, therefore, require continuous intake.
Vit A deficiency
Night blindness, Xerosis cutis Bitot spots Keratomalacia/xeropathalmia Immunosuppression
Eye sign of vit A deficiency
Bitot sqpots (grey triangles)
Overall functions of vit A
Gene transcription
Coenzyme
Cell signalling
Causes of vit A deficiency
Fat malaborption:
IBD, coeliac, CF, pancreatic insufficiency, cholestasis
Malnutrition
Immune effect of vit A deficiency
Immunosuppression: vitamin A deficiency increases the risk of a measles infection taking a severe course.
Functions of vitamin E
Protects against free radicals
T/F Vit E deficiency is common
F. It is very rare
Causes of vit E deficiency
Fat malabsorption disorders (e.g., cystic fibrosis)
Defects in genes that code for α-TTP
Clinical features of vit E deficiency
Demyelination of:
the posterior column (proprioception and vibration sensation)
and
spinocerebellar tract (causes ataxia and symptoms similar to vitamin B12 deficiency)
How to distinguish vit E from vit B deficiency
lack of hypersegmented neutrophils, megaloblastic anemia, and increased methylmalonic acid levels
Other features of vit E deficeincy
Hemolytic anemia: deficiency results in increased fragility of erythr`ocytes and membrane breakdown
Acanthocytosis
Muscle weakness
Function of vitamin K
Cofactor for γ-carboxylation of glutamic acid residues in vitamin-K-dependent proteins that are involved in
1) Coagulation: factors II (prothrombin), VII, IX, and X, proteins C and S
2) Bone formation: osteocalcin (bone Gla protein), matrix Gla protein
What drug affects vit K synthesis and how
Warfarin inhibits the vitamin K-dependent synthesis of clotting factors and proteins!
Causes of vit K deficiency
Liver failure (e.g., cirrhosis)
Fat malabsorption
Prolonged broad-spectrum antibiotic therapy
Vitamin K antagonists (e.g., warfarin)
What causes vit K deficeicny in neonates
The neonatal intestine is sterile (no flora to synthesize vitamin K)
Vitamin K does not cross the placenta
Breast milk does not contain vitamin K
The neonatal liver is incapable of synthesizing the active form of vitamin K
What is the clinical features of vit K deficeincy
Hemorrhage (e.g., petechiae, ecchymoses)
Vitamin K deficiency bleeding (VKDB)
Which vitamin is injected at birth
vITAMIN k
What is caused by vit b1 deficiency (thiamine)
Wernicke-Korsakoff syndrome
Beriberi
What is caused by vit b2 deficiency (riboflavin)
Conjunctivitis with corneal vascularization
Cheilosis
What is caused by vit b3 deficiency (niacin)
Pellegra:
Characterized by “the four D’s”: diarrhea, dermatitis/”da big tongue” (glossitis), dementia, and death - usually occurring in this order.c
What cancer can cause pellagra
carcinoid syndrome, a disease in which neuroendocrine tumors along the GI tract use tryptophan as the source for serotonin production, which limits the available tryptophan for niacin synthesis
Clinical features of vit C deficiency
Scurvy:
Hyperkeratosis, coiled corkscrew hairs, gingivitis mucosal bleeding, impaired wound healing, arthralgia, swollen joints, anaemia (normocytic or macrocytic)
