Albumin and Pre-Albumin

drop in intravenous (IV) drip.

Nutrition Status & Predictor of Mortality

The most abundant plasma protein is albumin, which is synthesised in the liver and functions as a carrier for fatty acids, vitamins, minerals, bilirubin, cortisol, thy­roxine and drugs. It also maintains osmotic balance between the extra and intravascular compartments of the body. Historically, albumin was used as a marker to assess protein status, since a decrease in availability of amino acids can result in the decreased synthesis of albumin. However, it is now known that specific physiological conditions can shift albumin to the extravascular space, resulting in a decrease in plasma albumin independent  of  overall nutritional status.

Illness, stress, inflammation, trauma  and surgery all trigger this extravascular shift due  to hormone and cytokine signalling. Other disease states, such as diabetes-induced glomerulosclerosis, lupus ery­thematosus, renal vein thrombosis, drugs, burns, cir­rhosis, rheumatoid arthritis and multiple myeloma, decrease albumin levels directly. The measurement of albumin levels is also dependent on the hydration state of the patient and administration of anabolic hormones. Given the long list of physiological con­ditions that affect albumin, its use as a marker of nutritional  status  can  lead to misinterpretation.

Pre-albumin   (transthyretin),   a  carrier protein  for vitamin A, is also  used as  a  marker  to  identify patients at risk of malnutrition. Similar to albumin, it is a negative acute phase protein that decreases in response to  metabolic  stress. It has  a  half-life of 2 days, in contrast to the 20-day half-life of albu­min. Monitoring of nutritional interventions through pre-albumin’s quick recovery has demon­strated improved treatment outcomes and has been incorporated into assessment protocols in several health-care settings. Consideration of dietary consumption, weight loss, serum proteins, wound healing and changes in medical status provide a more accurate assessment of nutritional status than reliance on serum proteins alone.

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