Metabolism and nutrition Flashcards
Define Cachexia
Weight loss and skeletal muscle wasting due to illness where the body does not reduce catabolism
(unlike the adaptive reduction in protein metabolism that occurs in starvation)
Predisposing factors for cachexia
Mechanisms not clearly understood
Pre-existing malnutrition / malabsorption.
Cytokine-induced up-regulation of muscle protein degradation
Neuro-endocrine – stimulation of hypothalamic-pituitary-adrenal axis
Reduced circulating anabolic hormones
Immobility and prolonged length of stay
Corticosteroid therapy
Malignancy
Ix to assess nutrtional status
Cholesterol and triglycerides
Random BSL
HbA1C
Serum cortisol
TFTs
FBC for lymphocyte count
Albumin and prealbumin
Transferrin
Calculation of nitrogen balance
Micronutrient levels:
- Fat-soluble vitamins A, D and E
- Thiamine
- Zinc
- Selenium
- Vitamin B12
- Folate
Indirect calorimetry
Delayed hypersensitivity skin-testing - detect poor immune function
Test for phaeo
Plasma free metanephrine
CT/MRI/PET
RQ - calculation
RQ = VCO2/VO2
NOrmal is 0.8
if high - could be due to a high carbohydrate foodsource and should therefore go on a fat and protein enriched diet.
Stress induced hyperglycaemia (S.I.H)
- definition
Transient hyperglycaemia during acute illness –usually restricted to patients without prior evidence of diabetes with reversion to normal after discharge.
SIH - mechanisms
complex interplay between counter regulatory hormones such as catecholamines, GH, cortisol and cytokines.
The underlying illness and treatments (TPN, enteral feed, steroids, and vasopressors) might affect the scale of these derangements.
Pt has a high hepatic glucose output
Insulin resistance plays a role.
Causes of severe hypoglycaemia in young diabetic patient
Accidental or non accidental overdose of long acting insulin
- Sepsis
- Glucocorticoid deficiency
- Hypothyroidism
- Insulin secreting tumour
- Less likely: severe liver disease
metabolic and clinical problems associated with overfeeding
Hepatic steatosis
Hyperglycemia
Hyperlipidemia
Hypercarbia
Hyperosmolarity and hypertonic dehydration (in patients fed excess nitrogen who have impaired urine concentrating ability)
Azotemia (due to excess nitrogen intake)
Causes of hyperglycaemia in ICU
Insulin resistance
- NIDDM
- Stress response
- Corticosteroid therapy
- Cushings disease
Inadequate insulin levels
- Under-supplemented
- Stress response
- Pancreatitis
- Haemochromatosis
- Insulin antibodies
Excessive endogenous glucose release
- Catecholamine infusion
- Stress response
- Glucagon administration
Excessive exogenous glucose supplements
- TPN with 50% dextrose
- Inappropriately sugary IV fluids
- Overfeeding with enteric nutrition
- Glucose-containing peritoneal dialysis fluid
Causes of adrenal insufficiency in the critically ill
Primary (ie. diseases of the adrenal gland)
- autoimmune (may have vitiligo), haemorrhage (eg. with sepsis and/or anticoagulant therapy), emboli, sepsis and adrenal vein thrombosis.
Secondary (interference with pituitary secretion of ACTH)
- destruction of pituitary by tumour/cellular inflammation, infection, head trauma, and infarction.
Tertiary (interference with hypothalamic excretion of CRF).
- include abrupt cessation of high-dose corticosteroids, and any process that interferes with the hypothalamus (tumours, infiltration, irradiation). The stress of critical illness can unmask adrenal insufficiency in patients at risk
Recommendations regarding immunonutrtion
No evidence to recommend arginine
No evidence to recommend fish oil or antioxidants
No evidence to recommend ornithine ketoglutarate
No evidence to recommend zink supplements
Some evidence to support the use of glutamine (this recommendation has been downgraded since 2009)
Some evidence to support selenium
Symptoms of hypothyroidism
Lethargy Depression Psychosis Decreased level of consciousness Cold intolerance Dry skin Hoarse voice Neck swelling (goitre) Postural dizzyness Gastro-oesophageal reflux Constipation Myalgia Amenorrhoea Decreased libido
Signs of hypothyroidism
Hair loss Loss of the lateral eyebrows (Queen Anne sign) Dry thickened skin Oedema (usually, non-pitting) Proximal muscle weakness Periorbital oedema Enlarged tongue Bradycardia Pericardial effusion Hypothermia Delayed reflexes
Laboratory features of hypothyroidism
Decreased T4 and T3 Increased TSH Hyperlipidaemia Hyponatremia Normochromic normocytic anaemia
