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Metabolism and Starvation - Coggle Diagram
Metabolism and Starvation
Recap on causes & effects of under-nutrition
Illness results in physical and metabolic changes or increased losses, increasing requirements
Psychological, physical, metabolic and iatrogenic factors all reduce intake
Physical and psycho-social effects
EFFECTS OF MALNOURISHMENT:
loss of muscle- breathing difficulties
micronutrient deficiency e.g. B vitamin deficiency if ETOH excess
decreased cardiac output
impaired gut integrity
Impaired wound healing
Inactivity predisposing to pressure sores
MUST tool helpful to identify effects of malnutrition-
MUST Tool: as malnourishment risk increases, time spent in hospital/number visits to hospital or GP increases, mortality increases in elderly malnourished (Stratton et al 2002)
How to carry out an in-depth assessment
Nutritional status: Not just intake but bodies ability to utilise it, are functions being maintained?, dispose of excess waste?
A,B,C,D,E
Consider how long they have been malnourished for
Think about fluid & electrolyte balance: what’s going in & what’s coming out
Think about GIT absorption: is it complete?
Find out what your biochem department can measure? Any micronutrients?
How can you visually assess your patient?
ESPEN guidelines
NICE guidelines CG32- MUST
40% weight loss if starting at healthy weight, becomes difficult to maintain life as lost too much lean tissue (5-10% in 3 months clinically significant)
MUST score may underestimate severity of risk in comparison to more complex assessments such as SGA and PGSGA. Renal patients at risk of this as fluid accumulation leading to inaccurate weight plus long term chronic ill health so not picked up on BMI (MUST criteria) = more detailed screening if patients more complex
A
patients trajectory with impaired intake- With catabolic response (inflammation) on top of starvation, weight loss is accelerated as muscles start dissolving further . MUST important to pick up weight loss early
Complete starvation time frame- starting from healthy body weight, will have reached 40% cut off within 60 days
If inflammatory response, will reach around 20 days as muscle catabolism being driven by inflammatory response
Need to identify history of weight loss and well weight – many patients take a long time before being referred
Electrolyte composition of body fluids (mmol/l)-
Physiology of starvation
Consider sites of absorption of nutrients in digestive tract and if patient has part of their digestive tract not fully functioning
Haemotology and biochem.- in general population, iron, Ca, vitamin C and folate may be low. e.g. 65yr+ female, 25% vit D deficiency
Physical signs of malnutrition e.g. pitting nails in iron deficiency, oral candidiasis
Look for signs of loss of SAT and oedema e.g. may be very malnourished but masked by fluid so ask if can look at collar bone, scapular as may be more bony in these areas
surface anatomy - study of external body surfaces
Metabolism of starvation- changes in metabolism from reduced food intake. thyroid hormone reduces metabolism.
Phases of adaptation/ starvation:
Glycogenolytic; 1st day total starvation
Gluconeogenesis; decrease insulin, increase glucagon
Ketogenic - after 3-4 days, by 3 weeks adapted to starvation
Metabolic response to starvation-
Energy conservation measures:
Leptin levels decrease, slight chnage in growth hormones, catecholamines (boost breakdown of fat)
Loss in muscle , gut , liver and fat after long fast affecting ability to absorb and metabolise nutrients (gut and liver function impaired)
Gut atrophy occurs after starvation in mice. could explain why diarrhoea occurs after refeeding
in starvation, heavier you are, more efficient you are at using fat so less protein used. thinner will break down more protein to provide energy
Physiology of refeeding syndrome
Ability to apply this knowledge to case studies
Simple fasting:
proteina dn glycogen mobilsed to provide glucose. Long term: glycogen and protein mobilised to provide glucose which is counterproductive in long term resulting in ketogenesis/ketosis and glucose needs fall (metabolic rate falls)
Problem with undernutrition:
leads to physical and psych-social problems. >5-10% weight loss is sig. in 3-6 months. impiared wound healing. hypothermia, impiared immune function and fertlity , osteoporosis, loss of muscle strength including organ function , anorexia, micrnutrient deficiciencies
Sites of absoprtion: Fats are first (duodenum) along with minerals (Fe, Zn, Ca) and fat soluble vitamins. Amino acids simple peptides follow with water soluble vitamins (jejunum) then bile salts and vitamin b12 (ileum). Water with Na and K in colon with more vitamins.