vitamin deficiency B K E Flashcards
sources of vitamin K
green leafy veg
oils - olive, cotton sead and soya bean
green peas and beans
watercress
asparagus
spinich
broccoli
oats and whole wheat
synthesised by colonic bacteria
role of vit K
essential lipid sol vitamin
co-factor in synth of clotting factors 2, 7, 9 and 10
important in bone health
vascular health
effect of vitamin K deficiency on bone health
cause impaired activation of bone matrix protein osteocalcin
reduction of osteoblast fyunction
= impaired bone function
epidemiology of vitamin K deficiency
any age
neonates at risk of vitamin K deficiency bleeding - lack of vit K reaching foetus across the placenta, low level of vit K in breast milk and low colonic bacterial synthesis
uncommon in otherwise healthy adults
RF for vitamin K deficiency
Excessive anticoagulation with coumarins - eg, warfarin
liver disease - cirrhosis, malignancy, amyloidosis, and Gaucher’s disease - they decrease the synthesis of vit K dependent factors, reduced absorption of vit K
malabsorption - coeliac, tropical spure, Crohn’s, UC, ascariasis, short bowel syndrome (due to multiple abdo surgeries), bacterial overgrowth and chronic pancreatitis
biliary tract disease - common duct obstruction due to stones and strictures, PBC, cholangiocarcinoma, chronic cholestasis -> decrease in fat absorption and so deficiency of fat sol vitamins
malnutrition - alcoholism, parenteral nutrition w/o vit K supplements
drugs - colestyramine, salicylates, rifampin, isoniazid and barbiturates
diseases with endogenously produced coagulation inhibitors (lupus anticoagulant and antithrombins), and paraproteinaemias such as myeloma
massive transfusion
DIC
polycythaemia vera
nephrotic syndrome
CF
leukaemia
sx of vit K deficiency
only evident if hypothrombinaemia is present:
- bleeding - minor or trivial trauma
- any site - mucosal and SC bleeding such as epistaxis, petechiae, haematoma, GI bleeding, manorrhagia, haematuria, bleeding from gums
Ix for vit K deficiency
bleeding time, PT and APTT are high
Ab test for high level of des-gamma-carboxy prothrombin (DCP) protein in vit K absence (PIVKA)
plasma vit K
Mx of vit K deficiency
depends on severity of the bleeding and the underlying cause
in life threatening bleeds - FFP asministered prior to vit K
Vit K is available as phytomenadione and as synthetic water soluble analogue menadiol sodium diphosphate
IV injections should be given slowly - fast would cause bronchospasm and peripheral vascular collapse
IM injections may lead to severe haematoma formation at the injection site if clotting is impaired
prognosis of vit K deficiency
very good if recognised early and treated appropriately
morbidity correlates with severity of deficiency, but severe bleeding can be fatal
prevention of vit K deficiency
diet rich in vitamin K
give to neonates
menadiol sodium phosphate is a water soluble vitamin K derivitive that can be given orally to prevent deficiency in malabsorption syndromes
summarise vitamin K deficiency bleeding
haemorrhagic disease of the newborn
occurs 2-7 days postpartum
cause - no enteric bacteria to make vit K
baby well, bruising/bleeding
PT and PTT high
plts normal
prevention - vit K IM if high risk, or colloidal (mixed micelle) phytomenadione at birth repeated in <7days, and if breast fed at 1mo (bottle feed already fortified)
Mx - plasma IV and vit K slow IV for acute bleeding - monitor coagulation
epidemiology of vitamin E deficiency
very rare
aetiology of vitamin E deficiency
fat malabsorption disorder eg CF
defects in genes that code for a-TTP (the transport for vit e)
clinical features of vit e deficiency
neurological dysfunction:
- demyelination of posterior column and spinocerebellar tract = reduced proprioception and vibration sensation, ataxia
- neurological sx similar to B12 def - but vit e def doesnt = hypersegmented neutrophils, megaloblastic anaemia and increased methylmalonic acid levels
haemolytic anaemia - deficiency = increased fragility of erythrocytes and membrane breakdown
acanthocytosis - dismorphic RBCs with thorn like cytoplasmic projections
muscle weakness
functions of vit e
antioxidant
- prevents free radical damage, especially in RBC at cell membranes
- interrupts free radical chains and oxidises itself as a result
inhibition of platelet aggregation, cell proliferation and monocyte adhesion
enzyme inhibition - protein kinase C, phospholipase A2
inhibition of gene transcription - eg a-TTP, tropomyosin alpha-1 chain
sources of vitamin e
meat
eggs
veg oil
leafy veg
management of vitamin e deficiency
daily requirement approx 3-15mg
little evidence supplements are useful in adults, even if they have malabsorption
in children with neuromuscular abnormalities and abnormally low vit e conc because of congenital cholestasis - only respond to parenteral admission of vit e
alpha tocopheryl acetate
function of vitamine B1
co-factor for enzymes involved in carb and AA metabolism:
- pyruvate dehydrogenase - pyruvate to acetyl-CoA
- a-ketoglucartic acid dehydrogenase - a-ketoglutarate to succinyl-CoA
- transketolase
- branched chain ketoacid dehydrogenase
aetiology of vitamin B1 deficiency
heavy drinking
malnutrition, starvation
malabsorption
malignancy
diarrghoea, prolongued vomiting
diuretics, haemodialysis
bariatric surgery
pathophysology of thiamine deficiency
thiamine deficiency -> impaired glucose breakdown -> ATP depletion -> tissue damage - primarily affects highly aerobic tissues eg brain/heart
high dose glucose infusions lead to increased ATP depletion = wernicke encephalopathy
therefore thiamine should be given before glucose infusions for chronic alcohol abusers
beriberi
inadequate thiamine uptake due to malnutrition, heavy drinking or increased demand - hyperthyroidism/pregnancy
clinical features of beriberi
dry
- symmetrical peripheral neuropathy - sensory and motor
- progressive muscle wasting
- paralysis
- confusion
wet
- cardiomegaly
- oedema
- high output cardiac failure - dilated cardiomyopathy
clinical features of vit B1 deficiency
beriberi
infantile beriberi - cardiomegaly, tachycardia, cyanosis, aseptic meningitis (vomiting and seizures)
wernicke encephalopathy
leigh syndrome (subacute necrotosing encephalomyopathy)
Koprsakoff’s syndrome
Ix for B1 deficiency
B1 administration = high RBC transketolase activity
Mx for B1 deficiency
irgent replacement to prevent irreversible korsakoff’s
give thiamine (Pabrinex) IV or IM for 30min for 2days, then 1 pair OD for 5days, then oral until no longer at risk
thiamine before glucose
prognosis of B1 deficiency
untreated death in 20%
korsakoff in 85% - 1/4 of which need long term institutional care
korsakoff’s syndrome
hypothalamic damage and cerebral atrophy due to B1 (thiamine) deficiency
reduced ability to acquire new memories, confabulation (invented memory due to retrograde amnesia), lack of insight and apathy
causes of vitamin B2 deficiency
malnutrition
vegan. lactose free
increased demand - pregnancy, lactation
(found in meat, fish, eggs, milk, green veg)
clinical features of B2 deficiency
corneal vascularisation
chelitis
glossitis
stomatitis
pharyngitis
normocytic normochromic anaemia
seborrheic dermatitis
Ix of B2 deficiency
erythrocyte glutathione reductase assay - identifies subtle deficiencies
erythrocyte glutathione reductase activity coefficient
causes of vit B3 deficiency
malnutrition - meat (liver), cereal, seeds, legumes
heavy drinking
conditions associated with tryptophan deficiency - Hartnup disease (decreased absorption), carcinoid syndrome (increased metabolism)
vit B6 deficiency - decreased B3 synth (niacin) from tryptophan
chronic consumption of grains that have not been produced by nixtamalization
clinical features of B3 (niacin) deficiency
glossitis
pellegra:
- classical traid of diarrhoea, dementia, dermatitis (circular broad rash in the neck - Casal necklace - affects C3 C4 and hyperpigmented skin lesions in sun-exposed areas)
- +- neuropathy, depression, insomnia, tremor, rigidity, ataxia, fits
- endemic in china and Africa
Mx of pellegra
education
electrolyte replacement
nicotinamide
vitamin B5 deficiency (pentothenic acid)
rare
caused by malnutrition - found in liver, kidney, egg yolks, broccoli, milk
features:
- adrenal insufficiency
- alopecia
- dermatitis
- enteritis
- may -> distal parasthesias and dysesthesias - burning sensation of feet
causes of B6 (pyridoxine) deficiency
malnutrition - nuts, wholegrains, vegetables, yeast, meat (liver, and poultry)
heavy drinking
chronic renal failure
chronic hepatitis
drug interactions - isoniazid, oral contraceptives
clinical features of B6 deficiency
cheliosis, glossitis, stomatitis
sideroblastic anaemia - B6 def = heme synthesis dysfunction with impaired transfer of Fe to Hb = iron accumulation in RBC
irritability
seizures
peripheral neuropathy
functions fo B6
pyridoxole phosphate (PLP) is a coenzyme for transamination, decarboxylation, AA metabolism, glycogenolysis
involved in synth of:
- heme
- histamine
- niacin
- gluthathione
- cystathionione
- neurotransmitters:
- serotonine
- dopamine
- epinephrine
- norepinephrine
- GABA
functions of B7 (Biotin)
co-enzyme for varoius carbocylase enzyme complexes:
- fatty acid synthesis
- gluconeogenesis
- fatty acid reduction
causes of vit B7 (biotin) deficiency
malnutrition - plants (soy products, nutsO, animal products (liver, egg yolk, dairy)
small amounts are synthesised by intestinal flora
prolongued uise of AB - destruction of intestinal flora
excessive consumption of rare egg white - binds biotin in intestinal lumen = inhibition of biotin resorption
clinical features of biotin deficiency
dermatitis
conjunctivitis
enteritis
alopecia
myalgia
neurological sx - lethargy, mental status change, hallucinations, parasthesia
