Investigations (nutritional status)

These include:

• albumin and other plasma proteins such as transferrin
• 24 hour urinary urea nitrogen excretion: can be combined with measurements of nitrogen intake to estimate the nitrogen balance and the degree of catabolism. This is unreliable in renal or hepatic failure. It is often practically difficult to collect all urine.
• 24 hour urinary creatinine excretion: gives an estimate of skeletal muscle mass depletion; however, influenced by meat content of diet and renal function.
• 3-methylhistidine: a byproduct of myofibrillar protein catabolism; urinary excretion is proportional to muscle mass and rate of catabolism.
• indirect calorimetry to assess energy requirements
• immunological methods:
  • total lymphocyte count: increased if elevated risk of morbidity and mortality; cellular immunity is affected before humoral immunity; however, underlying clinical condition will also affect nutritional status
  • hypersensitivity skin testing: defective response suggested by some authors as a sensitive means of detecting malnutrition; however, far less practical than simple history and examination.

These indicators are really only any good in combination, and should not be used as a first line in the identification of malnutrition.