Albumin is the most abundant protein in blood and accounts for about 50% of all plasma proteins. It is synthesized by the liver and secreted immediately without storing.
The physiological regulators of albumin are the colloid osmotic pressure and the nutritional status. The metabolism of albumin depends on the synthesis, distribution over interstitium and intravascular compartment, and excretion. Normal blood plasma concentration is between 3.5 to 5 g/dL, and 60% of the total albumin is in the interstitial space. Mean half-life is about 28 to 36 days .
Main medical uses are pharmacological therapy, serum marker to monitor diseases, biomaterials, and vaccines.
- Hypovolemia with or without shock: During fluid resuscitation in patients with hypovolemia, intravenous albumin is suggested as a second-line therapy if there is an inadequate response to crystalloids. In critical-ill patients, the survival rate at 90 days showed no significant difference when treated with albumin or crystalloids as first-line therapy (RR 0.98; 95% CI, 0.92-1.04). Albumin group had more free days of ventilation and vasopressor therapy than the crystalloid group (mean difference 1.10 and 1.04, respectively).. The recommended dosage is 500 ml of albumin 5% and repeats every 30 minutes if necessary.
- Prevention of central volume depletion after paracentesis due to cirrhotic ascites: In a study by Runyon et al., albumin infusion has shown to improve cardiovascular function after large-volume paracentesis (over 5 liters) in patients with cirrhosis and tense ascites.  A meta-analysis by Bernardi et al., reported an overall decrease in mortality (OR 0.64; 95% CI, 0.41-0.98). It also prevents hyponatremia, elevation of BUN, aldosterone, and renin. The recommended dosage is one dose of albumin 25%, 5 to 10 g/L of ascites, for more than 5 lt fluid drained. When ascites drainage volume is less than 5 liters albumin infusion lack of benefit, however, based on consensus more than facts an International Ascites Club recommends the use of plasma expanders for less than 5 L fluid drained.
- Hypoalbuminemia is a common clinical finding in critically ill patients, malnutrition and other diseases. The mainstay of therapy is to treat the underlying cause. Data are insufficient to recommend albumin in hypoalbuminemia patients. In a few cases, albumin 25% can be used to relieve symptoms due to hypoalbuminemia, but there is a high risk of fluid overload. One meta-analysis evaluated mortality as an outcome in hypoalbuminemia patients receiving Albumin infusions. They concluded that there was no significant effect in mortality if hypoalbuminemia was corrected RR 1.59 (0.91–2.78). A clinical trial by Dubois et al. evaluated the effect of albumin infusion in organ function in critically ill patients with hypoalbuminemia. They reported an improvement in organ function and a higher caloric intake in those who received albumin versus placebo. Supplementation of albumin to malnourished patients with hypoalbuminemia is not recommended.
- Ovarian hyperstimulation syndrome is a serious complication of assisted reproduction technologies, leading to an increase in vascular permeability and a shift of intravascular volume into the third space. It can cause thromboembolic events or ischemia. Albumin 25% is indicated as a plasma volume expansion in addition to crystalloids (Grade C recommendation). Studies have not shown strong evidence of its efficacy. Dosage recommended: 15 to 20 mL/hr for 4 hours.  Albumin administration is not indicated to prevent ovarian hyperstimulation syndrome.
- Acute Respiratory Distress Syndrome (ARDS): It is used with loop diuretics in the treatment of ARDS when pulmonary overload and hypoalbuminemia are present. A small clinical trial demonstrated improvement in oxygenation, total fluid balance and hemodynamic function in patients who received albumin plus furosemide versus those with furosemide only, resulting in a reduction of organ failure. The recommended dosage is albumin 25 g plus furosemide over 30 minutes that may be repeated every 8 hours for up to 3 days.
- Acute nephrosis: This recommendation is based on a review article in 1977. Indicated to treat edema in patients with nephrotic syndrome refractory to cyclophosphamide and corticosteroids. Such cases may respond with loop diuretics and 100 mL of albumin 25% solution daily for 7 to 10 days. Newer small clinical trials have shown a good resolution of edema with loop diuretics and albumin infusion vs. diuretics alone in children with nephrotic syndrome. Despite low samples, there was a statistical difference.
- Hemolytic disease of the newborn: Albumin is indicated as an adjunct therapy to treat neonatal hyperbilirubinemia during exchange transfusions. The efficacy is believed due to its ability to bind unconjugated bilirubin. The recommended dose is 1 g/kg per dose of albumin 25% during exchange transfusion  A significant difference in the reduction of total bilirubin levels at 6 and 12 hours was seen in patients treated with albumin 1 hour before exchange transfusion versus those with only exchange transfusion (p < 0.001) The combined use of albumin with phototherapy is not indicated because may cause detrimental effects.
- Burn hypovolemia: Previously, albumin infusion was recommended in conjunction with crystalloids 24 hours after thermal injury if burns had covered more than 50% of the body surface or crystalloid therapy has failed. The current recommendation suggests it may be useful in terms of decreasing fluid volume requirements. A recent meta-analysis showed that albumin solutions for acute resuscitation in burn-injured patients have no benefit on mortality (RR 1.6; 95% CI, 0.63 to 4.08) but the total volume used during resuscitation was less (RR -1; 95% CI, -1.42 to 0.48) compared to non-albumin solutions.
- Extensive hemodialysis: About 20% to 55% of patients on hemodialysis develop hypotension during their hemodialysis session. High rate or excessive volume ultrafiltration are the main causes. Albumin 5% is used as a second line therapy when hypotension does not respond to crystalloids. One study compared the use of albumin versus crystalloids in hypotension during hemodialysis. The results showed no significant differences in the main and secondary outcomes, achievement of the ultrafiltration volume target, and time to restore blood pressure or treatment failure, respectively.
- Cardiopulmonary bypass: Albumin can be used as a colloid for priming extracorporeal circuit and for volume expansion in cardiopulmonary bypass. These recommendations are based on a study by Wilkes that showed a reduction of acute postoperative mediastinal hemorrhage after cardiopulmonary bypass in patients exposed to albumin solutions compared to another colloid. Moreover, another study reported a favorable result in the preservation of platelet counts and maintaining the colloid osmotic pressure during cardiopulmonary bypass compared to crystalloids.
Spontaneous bacterial peritonitis (SBP) is a significant cause of mortality in cirrhotic patients. Administration of albumin 1.5 g/kg within 6 hours and 1 g/kg on day 3 along with antibiotics have a better effect in preventing renal impairment and reducing mortality from 29% to 10% in cirrhotic patients with SBP compared to those receiving antibiotics only. Another clinical trial confirmed the benefit of this therapy with laboratory, cardiac and Doppler parameters. Improvement in portal vein flow volume (p = 0.01) and reduction of inflammatory marker TNFa in ascites (p = 0.04) were reported.
The regular price of intravenous albumin solution is around $0.5 to $6 per milliliter. Compared to saline solutions $0.01 to $0.1 per milliliter, albumin solutions are 60-times more expensive. Price takes place when saline solutions and albumin infusions have the same efficacy in the treatment of a disease.