Question 20

Outline your approach to the assessment of nutritional status in a critically ill patient, including the use of appropriate laboratory tests.

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College Answer

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.

•     Other  

(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.


An extensive examination of the methods of nutritional assessment is available elsewhere:

In brief, these are the key features one should mention in such an answer:


  • Premorbid weight and the pattern of its change
  • Premorbid nutritional routine
  • Diseases affecting gastrointestinal function (eg. coeliac disease)
  • Disease affecting satiety control (eg. Prader-Willi syndrome)
  • Factors influencing metabolic substrate utilisation (eg. thyroid dysfunction, hypoadrenalism, Cushings disease or corticosteroid therapy)


  • Observed quality of nails and hair (an indicator of chronic protein intake)
  • Subcutaneous fat measurements (triceps)
  • Muscle bulk and muscle tone of quadriceps and deltoids
  • Presence of oedema and ascites
  • Evidence of any specific micronutrient deficiency


  • BMI
  • Ideal body weight
  • Lean body mass

Biochemistry and physiology:

  • Cholesterol and triglycerides
  • Random BSL
  • HbA1C
  • Serum cortisol
  • TFTs
  • FBC for lymphocyte count
  • Delayed hypersensitivity skin-testing
  • 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

References is an excellent resource for all things nutrition-related.

Berger, Mette M., and Claude Pichard. "Best timing for energy provision during critical illness." Crit Care 16.2 (2012): 215.

Dhaliwal, Rupinder, et al. "The Canadian Critical Care Nutrition Guidelines in 2013 An Update on Current Recommendations and Implementation Strategies."Nutrition in Clinical Practice 29.1 (2014): 29-43.

de Souza Menezes, Fernanda, Heitor Pons Leite, and Paulo Cesar Koch Nogueira. "Malnutrition as an independent predictor of clinical outcome in critically ill children." Nutrition 28.3 (2012): 267-270.

Norman, Kristina, et al. "Prognostic impact of disease-related malnutrition."Clinical nutrition 27.1 (2008): 5-15.

Detsky, Allan S., et al. "What is subjective global assessment of nutritional status." JPEN J Parenter Enteral Nutr 11.1 (1987): 8-13.

Sauberlich, Howerde E. Laboratory tests for the assessment of nutritional statusVol. 21. CrC Press, 1999.

Gorstein, Jonathan, et al. "Issues in the assessment of nutritional status using anthropometry." Bulletin of the World Health Organization 72.2 (1994): 273.

Shenkin, Alan. "Serum prealbumin: Is it a marker of nutritional status or of risk of malnutrition?." Clinical chemistry 52.12 (2006): 2177-2179.

Ritchie, Robert F., et al. "Reference distributions for the negative acute‐phase serum proteins, albumin, transferrin and transthyretin: a practical, simple and clinically relevant approach in a large cohort." Journal of clinical laboratory analysis 13.6 (1999): 273-279.

Desborough, J. P. "The stress response to trauma and surgery." British journal of anaesthesia 85.1 (2000): 109-117.

Klein, S. "The myth of serum albumin as a measure of nutritional status."Gastroenterology 99.6 (1990): 1845.

Don, Burl R., and George Kaysen. "Poor nutritional status and inflammation: serum albumin: relationship to inflammation and nutrition." Seminars in dialysis. Vol. 17. No. 6. Blackwell Science Inc, 2004.

Schoenfeld, Patricia Y. "Albumin is an unreliable marker of nutritional status."Seminars in Dialysis. Vol. 5. No. 3. Blackwell Publishing Ltd, 1992.

Shenkin, A., et al. "Laboratory assessment of protein-energy status." Clinica chimica acta 253.1 (1996): S5-S59.

Clark, Matthew A., et al. "Sequential changes in insulin-like growth factor 1, plasma proteins, and total body protein in severe sepsis and multiple injury."Journal of Parenteral and Enteral Nutrition 20.5 (1996): 363-370.

Casati, A., et al. "Rapid turnover proteins in critically ill ICU patients. Negative acute phase proteins or nutritional indicators?." Minerva anestesiologica 64.7-8 (1997): 345-350.

Rand, William M., Peter L. Pellett, and Vernon R. Young. "Meta-analysis of nitrogen balance studies for estimating protein requirements in healthy adults."The American journal of clinical nutrition 77.1 (2003): 109-127.


Hoffer, L. John, and Bruce R. Bistrian. "Appropriate protein provision in critical illness: a systematic and narrative review." The American journal of clinical nutrition 96.3 (2012): 591-600.

Kopple, Joel D. "Uses and limitations of the balance technique." Journal of Parenteral and Enteral Nutrition 11.5 suppl (1987): 79S-85S.