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Hypoalbuminaemia : Background and clinical significance

Hypoalbuminaemia is associated with an increased mortality and morbidity risk . Therapeutically , a good deal of evidence supports the use of albumin in the management and treatment of patients with a number of conditions , including severe liver diseases and their complications
Diana Alcantara-Payawal MD DTMH FPCP FPSG FPSDE Fatima University Medical Center ; and Cardinal Santos Medical Center , Manila , Philippines
Albumin is predominantly synthesised in the liver , although albumin mRNA is detected in extrahepatic locations such as the pancreas , kidney , and brain . 1 The rate of albumin synthesis is 150mg / kg / day , corresponding to 10 – 15g per day , and accounts for 10 % of hepatic protein synthesis . 1 Albumin is a good plasma volume expander due to its high oncotic activity and prolonged half-life in the intravascular compartment .
The primary physiological task of albumin is to maintain colloid osmotic pressure ( COP ) but researchers have also discovered other functions . These functions include ligand binding and the transport of various molecules with antioxidant and anti-inflammatory mechanisms . Hypoalbuminaemia is associated with poor outcomes in a number of conditions , including severe liver diseases , and an overview is given below .
Hypoalbuminaemia : a background Definition The normal serum range for albumin lies between 35 and 45g / l and hypoalbuminaemia is defined by a serum level below 35g / l . However , clinically relevant hypalbuminaemia probably occurs as levels drop below 25g / l . 2 Hypoalbuminaemia is not uncommon and was found to be present in 13 % of hospitalised patients . 3
Causes Table 1 summarises the main causes of hypoalbuminaemia . 2
Mechanisms responsible for adverse outcomes in hypoalbuminaemia There are a number of possible reasons to account for the association between hypoalbuminaemia and adverse clinical outcomes , which include :
• A reduction in colloid osmotic pressure
• Reduced ligand binding with albumin
• Oxidative damage
• Drug nephrotoxicity
• Increased inflammation .
Consequences of hypoalbuminaemia Hypoalbuminaemia is not a benign condition and a large number of studies and ensuing systematic reviews have examined the effect of hypoalbuminaemia on adverse outcomes in diverse patient populations , examples of which are given in Figure 1 .
FIGURE 1
The main causes of hypoalbuminaemia 2
Cause
Reduced albumin synthesis
Altered albumin distribution
Increased catabolism
Increased albumin loss
As seen in
Cirrhosis and liver failure Hepatitis Critical illness Malnutrition Chronic metabolic acidosis
Haemodilution ( e . g . due to pregnancy ) Decreased lymphatic clearance / increased transcapillary escape rate ( e . g . major surgery , burns , fluid loss , trauma , sepsis )
Infections , cancer , sepsis
Extensive burns Nephrotic syndrome
In a 1999 study of 54,215 non-cardiac surgery patients , serum albumin levels were found to be the best predictor of mortality and morbidity . The study revealed how a fall of 10g / l in serum albumin was associated with a greater than two-fold increased mortality and morbidity risk . 4
Other work has demonstrated that the presence of hypoalbuminemia prior to hospital admission is also a significant predictor of subsequent mortality and morbidity . In a study by Akirov et al , 5 the researchers examined the relationship between albumin levels upon admission and the change during hospitalisation and the impact of these changes . Their study included 30,732 patients , of whom 29 % had hypoalbuminaemia when admitted , which was mainly mild ( 24 %), defined as 25 – 35g / l but marked (< 25g / l ) in 5 % of patients . At the end of the follow-up period ( 1675 days ), 67 % of those with mild hypoalbuminaemia , 83 % with marked and 29 % of those with normal levels died . Furthermore , the length of hospital stay was significantly longer ( p < 0.01 for both comparisons ) in those with mild and marked hypoalbuminemia compared to patients with normal levels .
Hypoalbuminaemia can also significantly increase the risk of acute kidney injury ( AKI ), which in turn leads to a higher mortality rate . Wiedermann et al 6 found that for each 10g / l reduction in serum levels , the odds of AKI increased by
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