ALTERATIONS IN ALBUMIN METABOLISM AFTER SERUM AND ALBUMIN INFUSIONS

Paracentesis-induced circulatory dysfunction: are there albumin alternatives?

Background

Ascites is one of the main complications of advanced liver cirrhosis. It is defined as a pathological accumulation if free fluid in the peritoneal cavity.

Main body of the abstract

Ascites is a sign of decompensation in patients with liver cirrhosis and is associated with decreased survival. Ascites is associated with bad cosmetic figure and poor quality of life. Ascites is a predisposing factor for developing hydrothorax, hernias, diastolic dysfunction, spontaneous bacterial peritonitis, and renal impairment especially hepatorenal syndrome. The main treatment is salt restriction and diuretics. By the time the patient become non-responder and develop tense ascites, abdominal large volume paracentesis is the treatment of choice. Its advantages are rapid, cheap, and 1 day hospitalization. The main drawback is the development of paracentesis-induced circulatory dysfunction (PICD) if no volume expanding drugs are used. PICD is associated with dilutional hyponatremia, renal impairment, so it is considered the silent killer. Albumin infusion is the standard preventive measure but since costly to other alternatives such as colloids, vasoconstrictors or lowering the standard doses of the albumin was studied and is promising.

Conclusions

This review summarized the effectiveness of other alternative drugs.

Low dose albumin for the prevention of renal impairment following large volume paracentesis in cirrhosis

OBJECTIVES

To evaluate the effect of low dose Albumin i.e. 4 grams per litre of ascitic fluid after large volume paracentesis (LVP) for the prevention of paracentesis induced circulatory dysfunction (PICD) related renal impairment in cirrhosis.

METHODS

Case records of all patients with cirrhosis who underwent LVP from January 12(th), 2011 till December 29(th), 2013 were reviewed. Patients were excluded if they had spontaneous bacterial peritonitis, creatinine >1.5 mg/dl, hepatoma or if volume of ascitic fluid removed was <5 litres. Data including age, gender, cause of cirrhosis, CTP score and volume of ascitic fluid drained were noted. In addition serum creatinine and serum sodium at baseline and one week post paracentesis were recorded.

RESULTS

Two hundred and fourteen patients with cirrhosis underwent LVP during the study period. One hundred and thirty nine patients met the inclusion criteria and were analyzed. Patients were divided into two groups based on the amount of albumin given. The amount of albumin given was 25 grams and 50 grams while the volume of ascitic fluid removed were 6.2±1 litres and 10.4±1.5 litres in groups A and B respectively. One hundred and eight patients were in group A while thirty one patients were in group B respectively. Both groups received albumin at a dose of 4 grams per litre of ascitic fluid removed. Mean age in both groups were 53 years. Hepatitis C was the commonest etiology in both the groups, followed by Hepatitis B. More than 70% patients in both the groups were in child class C. Serum creatinine at baseline and one week post LVP was 1.04±0.24 mg/dl and 1.07±0.35 mg/dl in GROUP A while 1.11±0.23 mg/dl and 1.41±0.94 mg/dl in GROUP B. (P value 0.35). Similarly, serum sodium at baseline and one week post LVP was 130 ±5.6 meq/lit and 129.6±5.9 meq/lit in GROUP A while 127.6±5.8 meq/lit and 128±6.2 meq/lit in GROUP B respectively. (P value 0.14).

CONCLUSION

This study suggests that 4 grams of albumin per litre of ascitic fluid drained is effective in preventing the PICD related renal impairment following large volume paracentesis in cirrhosis.

[Ascites, hepatorenal syndrome and spontaneous bacterial peritonitis in patients with portal hypertension]

Ascites, hepatic encephalopathy and variceal hemorrhage are three major complications of portal hypertension. The diagnostic evaluation of ascites involves an assessment of its etiology by determining the serum-ascites albumin gradient and the exclusion of spontaneous bacterial peritonitis. Ascites is primarily related to an inability to excrete an adequate amount of sodium into urine, leading to a positive sodium balance. Sodium restriction and diuretic therapy are keys of ascites control. But, with the case of refractory ascites, large volume paracentesis and transjugular portosystemic shunts are required. In hepatorenal syndrome, splanchnic vasodilatation with reduction in effective arterial volume causes intense renal vasoconstriction. Splanchnic and/or peripheral vasoconstrictors with albumin infusion, and renal replacement therapy are only bridging therapy. Liver transplantation is the only definitive modality of improving the long term prognosis.

Balancing volume resuscitation and ascites management in cirrhosis

PURPOSE OF REVIEW

Patients with cirrhosis have total extracellular fluid overload but central effective circulating hypovolaemia. The resulting neurohumoral compensatory response favours the accumulation of fluids into the peritoneal cavity (ascites) and may hinder renal perfusion (hepatorenal syndrome). Their deranged systemic haemodynamics (hyperdynamic circulatory syndrome) is characterized by elevated cardiac output with decreased systemic vascular resistance and low blood pressure.

RECENT FINDINGS

Molecular and biological mechanisms determining cirrhosis-induced haemodynamic alterations are progressively being elucidated. The need for a goal-directed assessment of volume resuscitation (especially with volumetric techniques) in patients with cirrhosis is becoming more and more evident. The role of fluid expansion with albumin and the use of splanchnic vasopressors in a variety of cirrhosis-related conditions has recently been investigated.

SUMMARY

The response to fluid loading in patients with advanced cirrhosis is abnormal, primarily resulting in expansion of their noncentral blood volume compartment. Colloid solutions, in particular albumin, are best used in these patients. Albumin may be effective in preventing the haemodynamic derangements associated with large-volume paracentesis (paracentesis-induced circulatory dysfunction), in preventing renal failure during spontaneous bacterial peritonitis and, in association with splanchnic vasopressors, in caring for patients with the hepatorenal syndrome.

Evaluation and management of patients with refractory ascites

Some patients with ascites due to liver cirrhosis become no longer responsive to diuretics. Once other causes of ascites such as portal vein thrombosis, malignancy or infection and non-compliance with medications and low sodium diet have been excluded, the diagnosis of refractory ascites can be made based on strict criteria. Patients with refractory ascites have very poor prognosis and therefore referral for consideration for liver transplantation should be initiated. Search for reversible components of the underlying liver pathology should be undertaken and targeted therapy, when available, should be considered. Currently, serial large volume paracentesis (LVP) and transjugular intrahepatic portasystemic stent-shunt (TIPS) are the two mainstay treatment options for refractory ascites. Other treatment options are available but not widely used either because they carry high morbidity and mortality (most surgical options) rates, or are new interventions that have shown promise but still need further evaluation. In this comprehensive review, we describe the evaluation and management of patients with refractory ascites from the prospective of the practicing physician.

Management of adult patients with ascites caused by cirrhosis

Ascites is the most common of the major complications of cirrhosis. The development of ascites is an important landmark in the natural history of cirrhosis and has been proposed as an indication for liver transplantation. The initial evaluation of a patient with ascites should include a history, physical evaluation, and abdominal paracentesis with ascitic fluid analysis. Treatment should consist of abstinence from alcohol, sodium restricted diet, and diuretics. This regimen is effective in approximately 90% of patients. The treatment options for the diuretic-resistant patients include serial therapeutic paracenteses, liver transplantation, and peritoneovenous shunting.

The effects of experimental malnutrition on albumin metabolism and distribution in rabbits

In order to determine the extent to which the concentration of albumin in plasma is maintained at the expense of the extravascular pool during protein-energy malnutrition, the rates of exchange between albumin in plasma (IA) and the extravascular pool (EA) and consequently the distribution of albumin between intravascular and extravascular pools (expressed as EA:IA) were measured in protein-energy-depleted and control rabbits. The fractional rates of synthesis (FSR) and catabolism (FCR), the concentration of albumin and the plasma volume (PV) were also measured. In animals in which protein-energy intake was reduced by 58% the concentration of albumin in plasma remained unchanged, whereas FCR decreased by 38% and FSR by 30%. No significant changes in EA:IA or PV were found. We conclude that albumin concentration during protein-energy depletion is not maintained at the expense of extravascular albumin, but by parallel changes in the rates of catabolism and synthesis.

Serum albumin

The liver manufactures albumin at a massive rate and decreases production in times of environmental, nutritional, toxic and trauma stress. Osmotic pressure is a basic evolutionary regulatory factor, and hormonal control over albumin production has been demonstrated. Where and why new or old albumin is degraded are questions which have not been clarified, although the vascular endothelium may well be the degradative site. Albumin is important as a transport protein, as a measure of evolution and as a model to study secretion following synthesis without the intervening steps of glycosylation. Investigations as to how this protein enters the endoplasmic membrane may well answer some of the questions concerning signal peptide insertion (288). The role of the urea cycle intermediate ornithine and its participation in polyamine synthesis, which has a positive effect on albumin synthesis, is under study. Likewise, the inverse relation between acute-phase protein synthesis and albumin synthesis regulated by interleukin 1 and other cytokines will merit further study. These are a few of the concepts which will be tested in the future.

Is albumin synthesis regulated by the colloid osmotic pressure? Effect of albumin and dextran on albumin and total protein synthesis in isolated rat hepatocytes

In order to study the influence of the colloid osmotic pressure on albumin and total liver protein synthesis, rat hepatocytes were isolated by collagenase perfusion and incubated in Krebs-Ringer-buffer for 4 h. The colloid osmotic pressure produced by different bovine serum albumin (BSA) or dextran 60 concentrations varied from 3 to 80 mm Hg. A physiological colloid osmotic pressure of 20 mm Hg was obtained with 5.7 g BSA or 3.7 g dextran 60 per 100 ml of buffer. Albumin synthesis was measured by Laurell rocket immunoelectrophoresis. Total liver protein and total secretory protein synthesis were determined by the measurement of 1-14C-leucine incorporation. Albumin synthesis was not primarily regulated by the colloid osmotic pressure as was demonstrated by a lack of inhibition after addition of BSA. There was no significant influence of the oncotic pressure on the incorporation of 14C-leucine into total liver proteins. The incorporation into total secretory proteins was inhibited by an increasing colloid osmotic pressure, mediated either by BSA or dextran, suggesting an inhibition of the secretion of plasma proteins other than albumin.

Turnover of autologous alpha 1-antitrypsin in a patient with congenital analbuminemia

Despite very low amounts of albumin (1.7 mg/100 ml) the total plasma protein concentration of a patient with congenital analbuminemia was only slightly reduced to 6.3 g/100 ml. The lack of albumin is compensated by high concentrations of many other plasma proteins. Among the plasma proteins measured, alpha 1-antitrypsin showed a particularly high level. To investigate the underlying mechanism of this increase we purified plasma alpha 1-antitrypsin from the patient, labelled it with 125I, and studied its turnover in the analbuminemic patient and two normal volunteers. A half-life of 15 days in the patient compared with 7.5 and 8 days in the normal volunteers was found. The calculated synthesis rate of alpha 1-antitrypsin was about twice as high in the patient as in the controls. Therefore, both a longer half-life and an increased synthesis rate contribute to the high level of alpha 1-antitrypsin in the plasma of the analbuminemic patient.

[The regulation of serum albumin in physiological and pathological conditions (author's transl)]

12 g of albumin are synthesized daily by the bound polyribosomes of all human liver cells together, corresponding to 10% of the intravascular albumin mass. The cell is producing a precursor albumin. During secretion albumin is liberated by splitting of a small peptide. Only 40% of the total body albumin is located intravascularly. 12g of albumin are degraded or excreted daily, 30% of it by the liver, the kidneys and the gastrointestinal tract. The main site of albumin catabolism is unknown. Albumin with a half-life of about 20 days is degraded at a constant fractional catabolic rate. The absolute rate of degradation varies depending on the plasma content. This mechanism allows an effective regulation of the serum albumin level. The fractional catabolic rate, however, is not completely fixed. It is slowly reduced if the serum albumin content is markedly reduced as in protein deficiency, the blind loop syndrome, cirrhosis, nephrosis, and diseases of the gastrointestinal tract. Infusion of albumin increases the fractional catabolic rate slowly. This must be taken in consideration substitution albumin in chronic diseases. The shift from the extravascular to the intravascular compartment is a short-term regulatory mechanism. The regulation of synthesis and degradation are independent from each other. The molecular mechanism of regulation of synthesis and degradation are unknown, partially due to inadequate methods.

Plasma protein catabolism by the perfused rat liver. The effect of alteration of albumin concentration and dietary protein depletion

1. The isolated perfused rat liver was used to study degradation rates of plasma albumin, transferrin and fibrinogen. 2. Constant fractional rates were observed for all three proteins even when the albumin concentration was drastically increased by the addition of large amounts to the perfusate pool. 3. Livers taken from rats deprived of dietary protein for 14-18 days showed greatly diminished fractional catabolic rates for albumin when perfused with blood from similarly deprived animals. 4. These rates could be restored to near-normal values by adding albumin or by perfusing with blood from normally fed rats. 5. These findings are consistent with the theory of pinocytosis as a step in the degradation of plasma proteins by hepatic parenchymal cells.