Albumin, Serum

Albumin is the most important protein and constitutes 55 " “65% of total plasma protein. Approximately 300 " “500 g of albumin is distributed in the body fluids, and the average adult liver synthesizes approximately 15 g/day. Albumins half-life is approximately 20 days, with 4% of the total albumin pool being degraded daily. The serum albumin concentration reflects the rate of synthesis, the degradation, and the volume of distribution. Albumin synthesis is regulated by a variety of influences, including nutritional status, serum oncotic pressure, cytokines, and hormones.

Normal range:

0 " “4 months: 2.0 " “4.5 g/dL

4 months ¢ ˆ ’16 years: 3.2 " “5.2 g/dL

>16 years: 3.5 " “4.8 g/dL

Use

Assess nutritional status

Evaluate chronic illness

Evaluate liver disease

Interpretation

Increased In

Dehydration

High-protein diet

Decreased In

Decreased synthesis by the liver:

Acute and chronic liver disease (e.g., alcoholism, cirrhosis, hepatitis)

Malabsorption and malnutrition

Fasting, protein " “calorie malnutrition

Amyloidosis

Chronic illness

Decreased growth hormone levels

Hypothyroidism

Hypoadrenalism

Genetic analbuminemia

Acute-phase reaction, inflammation, and chronic diseases:

Bacterial infections

Monoclonal gammopathies and other neoplasms

Parasitic infestations

Peptic ulcer

Prolonged immobilization

Rheumatic diseases

Severe skin disease

Increased loss over body surface:

Burns

Enteropathies related to sensitivity to ingested substances (e.g., gluten sensitivity, Crohn disease, ulcerative colitis)

Fistula (gastrointestinal or lymphatic)

Hemorrhage

Kidney disease

Rapid hydration or overhydration

Repeated thoracentesis or paracentesis

Trauma and crush injuries

Increased catabolism:

Fever

Cushing disease

Preeclampsia

Thyroid dysfunction

Plasma volume expansion:

CHF

Oral contraceptives

Pregnancy

Limitations

In clinical practice, one of the two dye-binding assays " ”bromocresol green (BCG) and bromocresol purple (BCP) " ”is used for measuring albumin levels, and systematic differences between these methods have long been recognized.

BCG methods are subject to nonspecific interference from binding to nonalbumin proteins, whereas BCP is more specific. BCP has been shown to underestimate serum albumin in pediatric patients on hemodialysis and patients in chronic renal failure. Chronic dialysis units often have little influence over the method.

Antialbumin antibodies are commonly found with hepatic dysfunction and are typically of IgA type.

Ischemia-modified albumin, in which the metal-binding capacity of albumin has decreased due to exposure to ischemic events, is a biologic marker of myocardial ischemia.