Serum 5-nucleotidase; characterization and evaluation in disease states

Abnormal liver enzymes: A review for clinicians

Liver biochemical tests are some of the most commonly ordered routine tests in the inpatient and outpatient setting, especially with the automatization of testing in this technological era. These tests include aminotransferases, alkaline phosphatase, gamma-glutamyl transferase, bilirubin, albumin, prothrombin time and international normalized ratio (INR). Abnormal liver biochemical tests can be categorized based on the pattern and the magnitude of aminotransferases elevation. Generally, abnormalities in aminotransferases can be classified into a hepatocellular pattern or cholestatic pattern and can be further sub-classified based on the magnitude of aminotransferase elevation to mild [< 5 × upper limit of normal (ULN)], moderate (> 5-< 15 × ULN) and severe (> 15 × ULN). Hepatocellular pattern causes include but are not limited to; non-alcoholic fatty liver disease/non-alcoholic steatohepatitis, alcohol use, chronic viral hepatitis, liver cirrhosis (variable), autoimmune hepatitis, hemochromatosis, Wilson’s disease, alpha-1 antitrypsin deficiency, celiac disease, medication-induced and ischemic hepatitis. Cholestatic pattern causes include but is not limited to; biliary pathology (obstruction, autoimmune), other conditions with hyperbilirubinemia (conjugated and unconjugated). It is crucial to interpret these commonly ordered tests accurately as appropriate further workup, treatment and referral can greatly benefit the patient due to prompt treatment which can improve the natural history of several of the diseases mentioned and possibly reduce the risk of progression to the liver cirrhosis.

Serum adenosine deaminase, 5' nucleotidase and malondialdehyde in acute infective hepatitis

Serum adenosine deaminase (ADA), 5' nucleotidase (5'NT) and malondialdehyde (MDA) were estimated in patients with acute infective hepatitis (AIH) along with the routine parameters of liver disease. Present study is done to evaluate these special parameters in patients with clinical history of AIH and to assess the utility of these parameters as diagnostic/ prognostic indices of liver function and to correlate special parameters with routine live function tests (LFT). ADA, 5'NT and MDA along with routine LFT was estimated in 25 patients with AIH and 25 samples from healthy voluntary blood donars served as the control group. Routine LFT was estimated by standard clinical chemistry procedures on dade behring analyser and ADA, 5'NT and MDA were estimated by berthlot reaction, fiske and subbarao method and thiobarbituric acid method respectively.Statistical analysis showed that serum ADA, 5'NT and MDA were significantly higher in patients as compared with the controls. There was a significant positive correlation between ADA and total bilirubin and MDA and total bilirubin. Hence we can conclude that these tests would be more sensitive to diagnose the patients with AIH and that the raised bilirubin levels could be looked upon, as a protective mechanism which the liver has evolved in order to combat oxidative stress.

Studies on some serum enzyme levels in various liver diseases

Serum alkaline phosphatase (ALP) (EC 3.1.3.1), 5'nucleotidase (5'NT) (EC 3.1.3.5), aldolase (ALD) (EC 4.1.2.13) and sorbitol dehydrogenase (SDH) (EC 1.1.1.14) were estimated in infective hepatitis, alcoholic hepatitis, chronic active hepatitis, obstructive jaundice, cirrhosis of liver and amoebic liver abscess. It was observed that serum ALP and 5'NT were significantly increased in all cases of chronic active hepatitis and obstructive hepatic disease. However, the elevation observed in the latter was much higher than the former. Serum SDH and ALD levels were elevated in all cases of infective hepatitis, studied though increase in the former was much higher than the latter, suggesting its significance in the diagnostic confirmation of this disease. Results presented suggest 5'NT and SDH as more reliable diagnostic test compared to ALP and ALD for obstructive jaundice and infective hepatitis respectively.

Clinical use of serum enzymes in liver disease

Some of the many enzymes found in hepatocytes can be measured in the serum and are used as tests of liver function. We now review the current knowledge of their physiology and pathophysiology and outline their clinical usefulness. We divide them into two categories: enzymes that primarily reflect cholestasis, such as the alkaline phosphatase, the 5'-nucleotidase, and the gamma-glutamyl transpeptidase, and those that primarily reflect hepatocellular necrosis, such as the aminotransferases. We also briefly discuss several enzymes of more limited usefulness.

Serum 5'-nucleotidase: automation of a manual assay and brief observations on values in patients with breast cancer

We have modified a manual assay method for the determination of serum 5'-nucleotidase so that the reaction product, phosphate, is assayed colorimetrically using a continuous flow system. The contribution of non-specific phosphatase enzymes is assessed in the presence of nickel ions which specifically inhibit 5'-nucleotidase. The detergent sodium lauryl sulfate is used to eliminate the need for deproteinization in the phosphate assay. We have measured 5'-nucleotidase activity in the sera of 123 breast cancer patients and correlated our data with the patients' clinical status. Receiver operating characteristic curve analysis showed the most advantageous cut-off point for indication of secondary spread to be 10 U/L. Using this cut-off point, 14% of patients who were clinically free of disease and 35% of patients with disease clinically present had elevated 5'-nucleotidase activity.

Serum 5'-nucleotidase of a breast cancer patient

Serum derived from the breast cancer patient included in this study was found to be a rich source of 5'-nucleotidase. In addition, it also contains nonspecific alkaline phosphatase. The properties of 5'-nucleotidase were studied by eliminating the interference of serum non-specific alkaline phosphatase by the preliminary incubation of serum in glycine-NaOH buffer containing ethylenediamine tetraacetate and magnesium. The enzyme has a pH optimum at 9.5. It is remarkably stable when held at 50 degrees C at pH 7.5, but it readily lost activity in the acid medium at pH 4.2. It hydrolyzes both the ribo- and deoxyribo-nucleoside 5'-phosphates. It has the highest preference for cytidine 5'-phosphate. Adenosine 2'- or 3'- phosphates are refractory to its action.

Activation of serum 5' nucleotidase by magnesium ions and its diagnostic applications

Magnesium ions increase the hydrolysis of adenosine 5' monophosphate (5' AMP) by human serum at pH 7.9 but not at pH 9.3. The additional hydrolysis at pH 7.9 is predominantly due to increased activity of the specific phosphatase 5' nucleotidase (5Nase). This increase is proportional to enzyme concentration and has been employed as a measure of 5Nase activity in a sensitive micro-estimation. The normal range for serum 5Nase activity by this technique was 0 to 20 mIU/ml. In a series of over 200 patients, raised values were found frequently in hepatobiliary disease and infrequently in bone disease. Assay of 5Nase activity gave a more reliable indication of the source of raised serum alkaline phosphatase than isoenzyme electrophoresis in agar gel. The correlation between activities of the two enzymes was low in bone disease generally, and fairly good in hepatobiliary disease. The closest correlation was found in patients with parenchymal liver disease.