Salivary Isoamylase Research Articles

Transient Macroamylasemia in a Severely Multiple-Handicapped Child Following the Development of Acute Bronchitis

Macroamylasemia is a condition of elevated serum amylase levels in which normal serum amylase form a complex with high molecular weight proteins such as immunoglobulins. This is a case report on a patient with macroamylasemia following acute asthmatic bronchitis. A 5-year-old male with cerebral palsy and developmental retardation was admitted to our hospital because of high fever and severe cough. Treatment of the respiratory symptoms provided symptomatic improvement, but the serum amylase levels became suddenly elevated. Although acute pancreatitis associated with respiratory infection was initially suspected, a predominant salivary isoamylase, normal serum lipase level, low urine amylase level, and low amylase-creatinine clearance ratio (ACCR) (0.58%) indicated macroamylasemia. The serum amylase level decreased, and the ACCR increased within normal range 2 weeks after discharge. Both of these indicators have been within normal range over the past year. Transient macroamylasemia can be misdiagnosed as acute pancreatitis, especially in a severely multiple-handicapped child who is unable to complain. The ACCR is useful in the diagnosis of macroamylasemia.

臨床経過と矛盾する原因不明の高アミラーゼ血症の解析―骨髄腫細胞はシアリル唾液型アミラーゼを産生する―

There have been several reports describing a notable hyperamylasemia in patients with multiple myeloma. Such amylase-producing myelomas have been mainly described in the context of concomitant with salivary-type hyperamylasemia and with sialyl salivary-type amylase identified in a portion of those cases. Sialyl salivary-type amylase, with an abnormal anodic migration, was detected by isoamylase electrophoretic analysis. The abnormal isoamylase bands migrated toward the anode faster than the salivary isoamylase band (S2). The isoamylases were showed sensitive by neuraminidase treatment and were reacted with anti-human salivary monoclonal antibody. The isoamylases could be separated from residual normal isoamylase by using gel permeation chromatography. This paper reports the clinical laboratory findings indicating of sialyl salivary-type amylase in a patient with multiple myeloma.

Low serum amylase levels in drinking alcoholics.

We have reported that the serum level of amylase, different from other pancreatic enzymes, increases temporarily after abstinence in alcoholics. To elucidate the mechanism of this phenomenon, pancreatic isoamylase, salivary isoamylase, and amylase in urine were measured together with total serum amylase. Total serum amylase, pancreatic isoamylase, and salivary isoamylase values were measured in 38 male patients admitted to the National Alcoholism Center, Kurihama Hospital, for alcoholism after abstinence. In an investigation of amylase secretion, amylase in urine was measured in some patients after abstinence. In the group with abnormally high total serum amylase on admission, levels were found to decrease after abstinence. In patients with pancreatic disorders in this group, abstinence leads to a decrease in total serum amylase, but in patients with no such disorders, total serum amylase increases temporarily due to increases in salivary isoamylase. In the group with normal total serum amylase on admission, levels increased sharply after abstinence, and both pancreatic isoamylase and salivary isoamylase contributed to the gains. In the group with low total serum amylase, a sharp increase of 2-fold or more was noted after abstinence, and a major contributor was pancreatic isoamylase. The ratio of urine amylase to total serum amylase gradually declined, indicating clearly that abstinence led to a decrease in the excretion of amylase in urine. In cases of heavy alcohol consumption, a decrease in the production or secretion of pancreatic isoamylase and salivary isoamylase while drinking could happen. It was thus suggested that the increase in serum amylase might be due to the fact that this situation is improved by abstinence, plus the fact that excretion of amylase in urine increases during alcohol consumption, and abstinence brings about a decline in such excretion. Measurement of total serum amylase is not appropriate for diagnosing pancreatitis in alcoholic patients or those who consume large quantities of alcohol.

Isolated pancreatic amylase deficiency: Probable error in maturation

A boy with failure to thrive and isolated pancreatic amylase deficiency is described. Immunoprecipitation confirmed only salivary isoamylase in duodenal fluid at ages 20 and 33 months. Because normal pancreatic amylase messenger RNA was detected by reverse-transcriptase polymerase chain reaction in the fluid, failure of the normal maturation of pancreatic amylase secretion may explain the deficiency.

Postoperative Hyperamylasaemia in Cardiac Surgery

The mechanism of postoperative hyperamylasaemia was studied in 48 patients undergoing coronary artery bypass grafting (CABG). Mild hyperamylasaemia developed in 87% of the patients, and in 10% the serum amylase activity was > 1 000 U/l. Serial measurements of serum salivary (S-) and pancreatic (P-) isoamylases indicated that hyperamylasaemia was highest 24 hours after CABG and consisted mainly of P-amylase component. Serum creatinine, creatinine clearance and urinary albumin concentration remained normal after CABG, excluding severe renal damage. The fractional clearance (i.e. relative to creatinine clearance) of P-amylase decreased more than that of S-amylase (from 3.6 to 0.9% vs 1.3 to 0.8%). Decreased rate of excretion into urine, rather than pancreatic cellular damage, is the main source of hyperamylasaemia after CABG.

Alterations of exocrine pancreas in end-stage renal disease do they reflect a clinically relevant uremic pancreopathy?

Serum pancreatic enzyme behavior, exocrine function, and morphology of the pancreas were studied in 28 patients with end-stage renal disease undergoing regular hemodialysis, in order to better delineate and assess the clinical relevance of the pancreatic alterations that occur in these patients. Twenty-eight healthy subjects served as controls. Initial studies included serum amylase, isoamylase, and lipase assays; fecal chymotrypsin measurement; and abdominal ultrasonography. The amylase, lipase, and chymotrypsin determinations, as well as ultrasound examination, were repeated four years later. None of the patients had clinical evidence of pancreatic disease at entry into the study, but one had had previous attacks of pancreatitis and another developed mild acute pancreatitis one month after entry. Initial mean serum enzyme levels were significantly higher in patients than in controls (amylase, pancreatic isoamylase, and lipase, P < 0.001; salivary isoamylase P < 0.05). Serum amylase was raised in 16/28 patients; pancreatic isoamylase in 15/28, and lipase in 7/28; these elevations were generally mild. Mean fecal chymotrypsin was significantly lower (P < 0.001) in patients than in controls: abnormally low values were found in 9/28 patients. Amylase, lipase and chymotrypsin measurements repeated after four years showed no significant difference with respect to the first study. Ultrasonographic changes were rare and mild: one patient had a small cyst in the pancreas head, another, an increase in echogenicity of the gland not related to age; these findings were unchanged at repeat examination. The results demonstrate that the frequent elevations of serum pancreatic enzymes and the rare sonographic changes found in patients undergoing hemodialysis do not generally reflect a relevant pancreopathy. However, the finding of significantly decreased fecal chymotrypsin may indicate the presence of pancreatic dysfunction in end-stage renal disease.

Glomerular Charge Selectivity in Type 1 (Insulin‐dependent) Diabetes Mellitus

Glomerular charge selectivity was assessed using the ratio of the clearance of pancreatic isoamylase to the clearance of the more anionic salivary isoamylase (CPAm/CSAm) in 12 normal subjects and 50 patients with Type 1 diabetes: 13 with normal albumin excretion and short duration of diabetes (< 5 years), 15 with normal albumin excretion and long duration of diabetes (> 15 years), 13 with microalbuminuria, and 9 with clinical nephropathy. None had serum creatinine > 200 mumol l-1. There were no significant differences in CPAm/CSAm between the normal subjects and the two groups of normoalbuminuric patients with Type 1 diabetes. CPAm/CSAm was significantly lower in diabetic patients with microalbuminuria or clinical nephropathy than in normoalbuminuric patients with Type 1 diabetes. When the 37 patients with normoalbuminuria and long-standing diabetes, microalbuminuria, and nephropathy were considered together, there was a significant negative correlation between CPAm/CSAm and albumin excretion rate (rs = 0.71, p < 0.001). Progressive impairment of glomerular charge selectivity at the molecular size of amylase (molecular mass 56 kDa) accompanies increasing albuminuria in Type 1 diabetes.

Glomerular Charge Selectivity in Primary Glomerulopathies

1. Glomerular charge selectivity was assessed using the ratio of the clearance of pancreatic isoamylase to the clearance of the more anionic salivary isoamylase (CPAm/CSAm) in 53 patients with primary glomerulopathies (minimal change nephropathy, idiopathic membranous nephropathy, IgA nephropathy) and a wide range of albumin excretion rates and in 31 healthy subjects. Fractional clearances of pancreatic and salivary isoamylases (FCPAm, FCSAm) and of albumin (FCAlb) were also measured. 2. CPAm/CSAm and FCPAm were negatively correlated with FCAlb for the whole patient group (rs = -0.56 and rs = -0.65, respectively, P < 0.0001 for both), but there was no correlation of FCSAm with FCAlb. 3. For patients with near-normal albumin excretion rates (< 100 mg/24 h), there was no difference in CPAm/CSAm between the three types of glomerulopathy or between patients and healthy subjects. 4. These data suggest that glomerular charge selectivity at the size of amylase (which is smaller than albumin) is progressively lost as albuminuria increases from normal to the nephrotic range. Size restriction progressively increases until albuminuria is very heavy. When the albumin excretion rate is near normal, charge selectivity is also normal in the three main forms of primary glomerulopathy.

Total pancreatic and salivary serum iso-amylase activities in alcohol misusers in relapse and remission and in alcoholic liver disease

By means of immunoinhibition by specific salivary monoclonal antibodies in combination with a chromogenic substrate, assays of serum amylase were performed in control subjects, in chronic alcohol misusers in relapse or remission and in patients with alcoholic liver disease (ALD). There was a selective increase in the salivary isoenzyme in the ALD group. There were no significant changes in either of the alcohol misusing groups, compared with control subjects. It is suggested that the increase in salivary iso-amylase observed in patients with ALD is related to the previously reported functional and histological abnormalities in the parotid glands of this group of patients. It is also suggested that assay of pancreatic iso-amylase may be more discriminatory than total amylase levels in detecting pancreatic disease in patients with alcoholic cirrhosis.

Assessment of Glomerular Charge Selectivity in Man by Differential Clearance of Isoamylases

1. Glomerular charge selectivity was assessed using the ratio of the clearance of pancreatic isoamylase to the clearance of the more anionic salivary isoamylase (CPAm/CSAm) in 30 normal subjects, 14 patients with minimal proteinuria and 23 patients with heavy proteinuria due to primary glomerulopathies. Seven patients with minimal change nephropathy were studied in relapse and remission. 2. CPAm/CSAm exceeded 2.0 (range 2.1-6.1) in all normal subjects, indicating that the normal glomerular capillary wall possesses charge selectivity at the molecular size of amylase (molecular mass 56 kDa). 3. CPAm/CSAm was significantly lower in patients with heavy proteinuria than in normal subjects or patients with minimal proteinuria. CPAm/CSAm was low in patients with minimal change nephropathy in relapse and rose into the normal range with steroid-induced remission. 4. These data suggest that heavy proteinuria in primary glomerulopathies is accompanied by loss of glomerular charge selectivity. Remission of minimal change nephropathy is associated with restoration of normal charge selectivity.

Acute Pancreatitis

Hyperamylasemia has been reported in heroin addicts and ascribed to an increase of salivary isoamylase. Ours is the first report on acute pancreatitis in a heroin user. All prognostic parameters indicating a severe course of the disease were present, and computed tomography showed an edematous pancreatitis, but the acute pancreatitis took a benign clinical course.

A Prospective Study of Amylase-rich Pleural Effusions With Special Reference to Amylase Isoenzyme Analysis

By analysis of pleural effusions from 200 patients, 25 cases of amylase-rich effusions were identified, for an overall incidence of 13 percent. Four of the 25 patients (16 percent) had evidence of pancreatitis. These patients had higher mean ratios of pleural fluid to serum amylase levels (18 +/- 6.3 [SEM] vs 4.8 +/- 1.3) compared to patients with nonpancreatic diseases (p = 0.003); all four exhibited a predominant pancreatic isoenzyme profile. Of the 21 patients with nonpancreatic amylase-rich effusions, lung cancer was the most commonly associated condition (8 patients). In 14 of the 21 patients in whom an isoenzyme profile was obtained, salivary-type amylase was predominant. Amylase-rich pleural effusions occur frequently, and pleural fluid isoamylase determination is specific for pancreatitis-associated effusions. The finding of a pleural effusion rich in salivary isoamylase should prompt an evaluation for carcinoma (particularly of lung primary), but may also be seen in other pleural inflammatory conditions.

Macroamylases: Differences in Activity against Various-Sized Substrates

Hyperamylasemia caused by macroamylases can lead to the overdiagnosis of acute pancreatitis. We examined whether interference from macroamylase is less in assays that use high-molecular-mass (high-M(r)) substrates rather than oligosaccharide substrates. We hypothesized that high-M(r) substrates would be sterically excluded from macroamylasemic complexes and thus would be hydrolyzed less efficiently. Eighteen macroamylasemic samples were assayed by using red-dyed amylopectin or blue-dyed starch as polysaccharide substrates or by using maltoheptaose or maltotetraose as oligosaccharide substrates. The oligosaccharide substrates gave comparable results (y = 0.81x + 83), but we observed consistently lower activities for amylopectin than for maltotetraose (y = 0.32x + 38). We observed no bias among methods when nonmacroamylasemic specimens were analyzed. The mechanism of this difference was examined by adding antihuman pancreatic amylase antibodies to hyperamylasemic serum samples from patients without macroamylasemia and to purified human pancreatic or salivary isoamylases. In each case, polyclonal and monoclonal antibodies lowered amylase activity more in assays with complex polysaccharides than in those with oligosaccharides. The use of high-M(r) substrates diminishes interference, and detection of suspected macroamylasemia may be possible through comparing activities determined from automated methods that use different substrates.

Macroamylases: Differences in Activity Against Various-Size Substrates

Hyperamylasemia caused by macroamylases can lead to the overdiagnosis of acute pancreatitis. We examined whether interference from macroamylase is less in assays that use high-molecular-weight rather than oligosaccharide substrates. We hypothesized that high-molecular-weight substrates would be sterically excluded from macroamylasemic complexes and thus would be hydrolyzed less efficiently. Eighteen macroamylasemic samples were assayed by using red-dyed amylopectin or blue-dyed starch as polysaccharide substrates or by using maltoheptaose or maltotetraose as oligosaccharide substrates. The oligosaccharide substrates gave comparable results (y = 0.81x + 83); we observed consistently lower activities for amylopectin than for maltotetraose (y = 0.32x + 38). We observed no bias among methods when nonmacroamylasemic specimens were analyzed. The mechanism of this difference was examined by adding anti-human pancreatic amylase antibodies to hyperamylasemic serum samples from patients without macroamylasemia and purified human pancreatic or salivary isoamylases. In each case, polyclonal and monoclonal antibodies lowered amylase activity more in assays with complex polysaccharides than in those with oligosaccharides. The use of high-molecular-weight substrates diminishes interference, and detection of suspected macroamylasemia may be possible through comparison of activities determined from automated methods that use different substrates.

Separation and characterization of sialic acid-containing salivary-type amylase from patients' sera with immunoglobulin A-type myeloma

Isoamylases, with an abnormal anodic migration, were detected by an electrophoretic technique in the sera from two patients with immunoglobulin A-type myeloma. The abnormal isoamylase bands migrate towards the anode faster than the salivary isoamylase (S 2) band and were stained more strongly than the S 2 sub-band. The abnormal isoamylase could be separated from patients' sera by using size-exclusion high-performance liquid chromatography. The serum abnormal isoamylases were showed to be sialic acid residues containing amylase, after the study of treatment with neuraminidase (EC 3.2.1.18), and to be salivary-type amylase, after the study of reaction with human salivary monoclonal antibody. The abnormal bands were not detected in the saliva from one patient. The two patients had no detectable malignancies except myeloma. These findings strongly suggest that the sialic acid-containing salivary-type amylases were produced ectopically from myeloma cells. In this regard the ectopic amylase production by myeloma cells is discussed.

Lipase and Pancreatic Amylase Activities in Tissues and in Patients with Hyperamylasemia

Lipase, pancreatic amylase, and total amylase activities were measured in nondiseased and diseased human pancreatic tissues and in six different locations of the human digestive system. In addition, it was determined whether serum lipase and pancreatic amylase tests could replace the total amylase test to improved diagnostic efficiency in the evaluation of acute pancreatitis in hyperamylasemia patients. Nondiseased pancreatic tissue contained 4.5 times more lipase activity than total amylase activity. Diseased pancreatic tissue contained less activity for both lipase and total amylase compared to normal tissue. The total amylase activity of the pancreas was comprised solely of pancreatic amylase. Tissue obtained from six different anatomic locations in the digestive system contained 35 to 45 times less lipase and total amylase activity compared to the pancreas. Total amylase activity of the digestive system tissues were comprised of 25% pancreatic and 75% salivary isoamylases. Lipase, pancreatic amylase, and total amylase levels also were determined in serial serum samples from 17 consecutive hyperamylasemia patients admitted with possible acute pancreatitis. The serum lipase level remained higher than normal longer than either the total amylase and pancreatic amylase levels. In patients with hyperamylasemia of pancreatic origin, a poor correlation was observed at admission between serum pancreatic amylase and serum lipase. Not all patients with elevated lipase had an elevated pancreatic amylase level and vice versa. However, in every patient pancreatic disease would have been detected by the elevation of either lipase or pancreatic amylase levels. Diagnostic efficiency for pancreatic disease using serum pancreatic amylase, lipase, and total amylase tests was 94.1%, 76.5%, and 64.7%, respectively. These data suggest that lipase and pancreatic amylase tests are specific for the pancreas and might be considered replacements for total amylase as the stat or routine laboratory test for the diagnosis of pancreatic tissue injury.

Clinical significance of chronic hyperamylasemia

A longitudinal study of patients with persistent hyperamylasemia was carried out to evaluate the clinical significance of this condition. Twenty-five outpatients were studied by means of serum amylase, isoamylase (wheat germ-inhibition method), and lipase determination; macroamylase detection; and abdominal ultrasonography over a one-year period. Cellulose acetate electrophoresis was carried out to validate the wheat germ-inhibition tests; the results of the two assays were closely correlated, except in three patients with macroamylasemia. At the time of the study, none of the patients had evident signs or symptoms of pancreatic disease. At initial evaluation, wheat germ test demonstrated an elevation of only salivary isoamylase in 16 patients, both pancreatic and salivary isoenzyme in two, and only pancreatic isoamylase in six patients (three with macroamylasemia). Normal salivary and pancreatic isoenzymes were found in one with predominantly pancreatic isoamylase. At the 12-month follow-up, hyperamylasemia had disappeared in six cases and salivary isoamylase elevation in three; pancreatic isoamylase remained abnormally high in all eight patients in whom it was elevated at initial evaluation, and lipase was abnormally high in three patients with elevated pancreatic isoamylase. Of the five patients with true pancreatic hyperamylasemia, one had a juxtapapillary duodenal diverticulum, one showed a slight ultrasound alteration of the pancreas, and one had a past history of acute pancreatitis. In our study, most cases of chronic hyperamylasemia were of nonpancreatic origin. In the patients with elevated pancreatic isoamylase, there was no clinical evidence of pancreatic damage, although a subclinical pancreatic involvement could not be excluded in some.

Isoamylase levels in bone marrow transplant patients are affected by total body irradiation and not by graft-versus-host disease

The mean total serum amylase levels in patients was 3.2 +/- 0.5 mukat/l (+/-SE) before total body irradiation (TBI) prior to bone marrow transplantation of which 50% was due to pancreatic isoamylase and 50% salivary isoamylase. Total serum amylase increased to a maximum of 100.3 +/- 12.3 mukat/l on the first day after TBI and most of this increase was due to an increase in salivary isoamylase (90.0 +/- 12.1 mukat/l). In association with this, all patients had clinical symptoms of parotitis. An increase in pancreatic isoamylase was found in 27% of the patients; however, none of them had clinical symptoms of pancreatitis. Serum amylase levels returned to normal within 5 days after TBI but then decreased to subnormal values, remaining below the normal range for 3 weeks. Pancreatic isoamylase returned to pre-irradiation levels 1.5 months after TBI, while salivary isoamylase remained low for the rest of the observation time. TBI of 7.5 Gy at 26 cGy/min gave significantly lower salivary amylase at 2 days after TBI compared with 10 Gy at 4 cGy/min: 32 +/- 4 versus 76 +/- 13 mukat/l (P less than 0.05). At 2.5 and 6 months after TBI significantly higher total amylase levels were recorded for patients treated with 7.5 Gy of TBI compared with 10 Gy: 2.5 +/- 0.4 and 2.7 +/- 0.3 versus 2.0 +/- 0.5 and 0.8 +/- 0.3 mukat/l, respectively (P less than 0.01, P less than 0.05, respectively). Acute or chronic GVHD did not affect acinar cells in this investigation.

Hyperamylasemia in Inflammatory Bowel Disease

We determined the prevalance and significance of hyperamylasemia in 180 patients with idiopathic inflammatory bowel disease (IBD) (83 with ulcerative colitis, and 97 with Crohn's disease). Serum total amylase and pancreatic and salivary isoamylase activity were measured in all patients. In all patients with hyperamylasemia, we measured isoamylase activity by cellulose acetate electrophoresis and lipase activity, assayed for the presence of macroamylase, and carried out pancreatic ultrasound examination and barium studies of the upper gastrointestinal tract. Eight of 97 patients with Crohn's disease (8%) had hyperamylasemia; 4 of them had an elevated pancreatic isoamylase and 2 a raised lipase activity. All patients with hyperamylasemia had normal ultrasonographic scans of the pancreas and no evidence of duodenal involvement on barium meal. None had macroamylasemia. We found no relationship of hyperamylasemia to disease site, activity, and duration or therapy and no patient developed clinical evidence of pancreatitis. We conclude that a small but important number of patients with Crohn's disease have hyperamylasemia not associated with overt pancreatitis. In the absence of appropriate indications, it requires no investigation.

Multicenter evaluation of a specific pancreatic isoamylase assay based on a double monoclonal-antibody technique.

Eleven evaluators from nine laboratories in five countries evaluated a new immunoinhibition method for pancreatic isoamylase determination that is as simple to perform as that for total amylase. The precision at low and intermediate activity concentrations was superior, and at high concentrations it equalled that of the wheat-germ inhibitor method. The test was linear to approximately 2000 U/L, depending on the instrumentation used. The percentage salivary isoamylase activities remaining in specimens after reaction with two monoclonal antibodies ranged from 2 to 4.4%. Comparative studies showed good correlation with the wheat-germ inhibitor (r greater than 0.978) and electrophoresis methods (r = 0.920). Hemolysis, lipemia, and bilirubinemia have no effect on results. Interlaboratory studies demonstrated excellent transferability of the method, if instruments are calibrated with the same calibrator. Reference intervals for pancreatic isoamylase are 13 to 64 U/L (25 degrees C), 13 to 83 U/L (30 degrees C), and 17 to 115 U/L (37 degrees C). A clinical evaluation of patients with acute pancreatitis showed that pancreatic isoamylase has a greater clinical sensitivity than total amylase.