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Albumin: Facts and Function
Contributed by Eleanor Schiavo, MS, RD
Review Date 11/21/15
Albumin
• One of a group of proteins found
throughout plant and animal tissues
• Serum albumin: found in blood
• Lactalbumin: found in milk
• White of eggs as ovalbumin
• Name derived from Latin word albus,
meaning white
Serum Albumin
• Produced in the liver (visceral protein); a
measure of hepatic function
• One of a group of proteins known as total
serum protein: prealbumin, albumin, and
globulins
• Located primarily in the extravascular
space
Normal value:3.5-5 g/dL or 35-50 g/L
Albumin
• Composed of 584 amino
acids
• 9-12 grams (g) albumin
produced per day
• Takes place in the vascular
endothelium
Distribution and
Metabolism of Albumin
• Albumin is synthesized in the liver
• 12 g are produced per day and 12 g are
broken down /day
• Plasma has 120 g of albumin
• Interstitial fluid has 165 g of albumin
Albumin Circulation
• Normally, albumin circulation takes 16 hours
o
intravascular space → interstitial compartment →
lymphatic system
• Clearance from the interstitium is dependent on
the lymphatic flow (normal = 120mL/hr)
• Lymph flow is dependent on interstitial fluid
pressure, intrinsic pumping by the lymphatic
vessels, and compression of muscles by muscle
contraction.
Functions of Albumin
•
•
•
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Binding and transport: Transport molecule for a large
number of metabolites: fatty acids, calcium, copper, thyroxine,
bilirubin, and amino acids. It also transports drugs.
Colloid osmotic pressure effect: Albumin makes up half
the normal intravascular mass. Responsible for 75-80% of the
plasma colloid osmotic pressure. Keeps fluid in the vascular
space
Free radical scavenging: limits free radical mediated
damage
Anticoagulant effect: may be a result of albumin binding to
nitric oxide (NO) radicals. NO takes longer to become inactive,
resulting in a prolonged anti-aggregation platelet effect.
Increase Serum Albumin
Levels
•
•
•
•
Infusion of fresh frozen plasma (FFP) or albumin
Decreased catabolism
Increased synthesis
Contraction of vascular compartment
Decrease Serum Albumin
Levels
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Protein-calorie malnutrition
Liver disease
Protein-losing enteropathies
Protein-losing nephropathies
Third-space fluid losses
Septic and postoperative patients
Protein Calorie Malnutrition
•
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Malnutrition due to inadequate intake of calories,
protein, or both
Marasmus versus kwashiorkor
A low albumin is seen in kwashiorkor. There is
impaired protein synthesis. Edema and ascites are
common.
Malnutrition is a common consequence of chronic
disease.
A decrease in albumin can be caused by inadequately
available amino acids. Liver dysfunction also
contributes to low albumin levels.
Liver Disease
•
•
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Cirrhosis occurs following liver damage.
Some fibrous tissue develops, impairing blood flow.
There is a loss of functioning liver cells
Since the liver is the site of albumin synthesis, a drop
in production leads to a decrease in albumin levels.
Protein-Losing Enteropathies
•
•
Large volumes of protein are lost from the intestines
because absorption is inadequate.
Malabsorption syndromes such as Crohn’s disease and
sprue are included in this category.
Protein-Losing Nephropathies
•
•
•
Large volumes of albumin can be lost through the
kidneys.
Nephrotic syndrome: characterized by increased
glomerular permeability to proteins. Results in
massive loss of proteins in the urine, edema,
hypoalbuminemia
Included in this category are glomerulosclerosis and
glomerulonephritis
Increased Serum Albumin Levels
•
•
•
•
Dehydration
Infusion of FFP or albumin
Increased synthesis
Contraction of vascular compartment
IV Albumin
•
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Extracted from donor plasma
Requires no ABO compatibility
testing
No confirmed reports of viral transmission
Pasteurized
There is a risk of transmission of infectious agents,
including viruses.
Contraindicated: cardiac failure or severe anemia due to
the risk of acute circulatory overload
Clinical Uses for IV Albumin Use
•
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Hemorrhagic shock
Cirrhosis
Nephrotic syndrome
Blood loss
Acute complications of chronic hypo-proteinemia
Volume resuscitation
Complications Associated With IV
Albumin
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Fluid overload
Coagulation defects
Hemolysis
Myocardial depression: possibly a result of Ca
binding
Allergic reactions are rare but could occur due to
contaminants formed during processing
Disadvantages of IV Albumin
•
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Costs 30 times more than crystalloid solutions
Albumin will not correct chronic
hypoalbuminemia: decreased albumin reflects
basic underlying problem that needs to be
corrected
The ability for albumin to remain in the vascular
space is dependent on capillary integrity
Volume Resuscitation
•
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Primary intervention for hypovolemia
Use either crystalloid or colloid solutions
Crystalloid solutions: contain only water and electrolytes
o
o
•
Primarily fill the interstitial space and edema is an expected negative
outcome
Normal saline is a crystalloid
Colloid solutions: Used when crystalloids are not effective
o
o
o
o
Contain water, electrolytes, and protein/synthetic macromolecules
Smaller amounts of colloids achieve the same results as much larger
volumes of crystalloids
Incidence of edema is reduced
Albumin is a colloid
Crystalloid Solutions
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Contain water and electrolytes: sodium potassium chloride
Varies in content of free water
Dextrose is added as a calorie source and a deterrent to the
ketosis of starvation
Contain the same number of cations to anions
Examples of uses:
o D5W supply calories and free water
o .9 NS expand plasma volume
o .45 NS supply NACL and free water
Conclusions
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Serum albumin is a non-specific marker of disease
processes.
Changes are the result of pathological events, not
the cause of them.
Abnormal albumin values should trigger a search
for the cause of the change.
There is little clinical evidence to support the
routine use of IV albumin supplementation.
References
Hermey C. Quick Reference for IV Therapy. St. Louis, MO: Mosby-Year Book
Inc.; 1995.
Margeson MP, Soni N. Serum albumin: touchstone or totem? Anaesthesia.
1998;53(8):789-803. doi:10.1046/j.1365-2044.1998.00438.x.
Mendez C, McClain C, Marsano L. Albumin therapy in clinical practice. Nutr Clin
Pract. 2005;20(3):314-320. doi:10.1177/0115426505020003314.
Metheny N. Fluid and electrolyte balance nursing considerations. 5th ed.
Burlington, MA: Jones & Bartlett Learning;2010.