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
