Outline your approach to the assessment of nutritional status in a critically ill patient, including the use of appropriate laboratory tests.
Answer and interpretation
History and physical examination:
- Indicators of malnutrition – recent involuntary weight loss, changes in appetite or bowel habit, presence of persistent GI symptoms, muscle wasting, signs of specific micro-nutrient deficiency e.g. glossitis, angular stomatitis, anaemia, bleeding gums, skin/hair/nail condition.
Ancillary blood tests:
- serum hepatic protein levels are linked to nutritional status and severity of illness.
- Serum albumin and pre-albumin levels. ( Albumin will be a better indicator of chronic nutritional status and pre-albumin serves more as a marker of changes in current nutritional status).
- Transferrin and coagulation factors: Useful but may more reflect the poor synthetic function of the liver in this case than nutritional deficiency per se.
- Fat-soluble vitamin deficiency levels of vitamins A, D and E should be checked. Water-soluble vitamin deficiency, (thiamine), is common in alcoholic liver disease and therefore levels of thiamine and other treatable vitamins e.g. zinc, selenium, Vit B12 and folate should also be checked.
(1) delayed hypersensitivity skin testing
(2) total lymphocyte count
(3) anthropometric measurements e.g. mid-arm muscle circumference and skin-fold thickness
(4) indirect calorimetry to measure energy expenditure – metabolic cart, VO2, VCO2,
(6) nitrogen balance – but calculations inaccurate in liver and renal failure.