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
DM
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.