For the last decade, low serum amylase (hypoamylasemia) has been reported in certain common cardiometabolic conditions such as obesity, diabetes (regardless of type), and metabolic syndrome, all of which appear to have a common etiology of insufficient insulin action due to insulin resistance and/or diminished insulin secretion. Some clinical studies have shown that salivary amylase may be preferentially decreased in obese individuals, whereas others have revealed that pancreatic amylase may be preferentially decreased in diabetic subjects with insulin dependence. Despite this accumulated evidence, the clinical relevance of serum, salivary, and pancreatic amylase and the underlying mechanisms have not been fully elucidated. In recent years, copy number variations (CNVs) in the salivary amylase gene (AMY1), which range more broadly than the pancreatic amylase gene (AMY2A and AMY2B), have been shown to be well correlated with salivary and serum amylase levels. In addition, low CNV of AMY1, indicating low salivary amylase, was associated with insulin resistance, obesity, low taste perception/satiety, and postprandial hyperglycemia through impaired insulin secretion at early cephalic phase. In most populations, insulin-dependent diabetes is less prevalent (minor contribution) compared with insulin-independent diabetes, and obesity is highly prevalent compared with low body weight. Therefore, obesity as a condition that elicits cardiometabolic diseases relating to insulin resistance (major contribution) may be a common determinant for low serum amylase in a general population. In this review, the novel interpretation of low serum, salivary, and pancreas amylase is discussed in terms of major contributions of obesity, diabetes, and metabolic syndrome.

The serum level of amylase (sAm) is commonly used as a biochemical marker for diagnosis and management of pancreatic disorders. However, the use of the urine level of amylase (uAm) is limited in practice, because the diagnostic ability of uAm is inferior to that of sAm. In the present study, the possible concordance of uAm-rerated parameters with sAm was investigated, and evaluate the usefulness of uAm for management of hyperamylasemia.

From June 1995 to October 2009, 804 samples of both urine and blood were collected from 128 patients in order to measure the serum level of amylase (sAm) and the urine level of amylase (uAm) and creatinine (uCr). Concordance of parameters using uAm compared to sAm was assessed. Parameters used were uAm, amylase creatinine clearance ratio (ACCR), and the ratio of uAm to uCr (uAm/uCr).

uAm/uCr had the best correlation with sAm (r = 0.779, p < 0.001) compared to uAm (r = 0.620, p < 0.001) and to ACCR (r = 0.374, p < 0.001), when sAm was over the standard level. The area under the receiver operating characteristic curve of uAm/uCr (0.884) was significantly higher than that of uAm (0.766) and of ACCR (0.666) (p < 0.001 for each). The cutoff value of uAm/uCr was 569.8, with a sensitivity of 81.0% and a specificity of 83.1%.

The uAm/uCr ratio correlated with sAm, and may be an alternative to sAm for prediction of hyperamylasemia. Use of urine samples results in a decreased need for blood sampling, which is especially beneficial in pediatric patients.

Several clinical and methodologic difficulties occur when diagnosing acute pancreatitis in the pediatric age group. Due to its uncommonness and heterogeneous symptoms, acute pancreatitis in children is often misdiagnosed, and prospective studies are lacking. Guidelines for classifying, diagnosing, and managing acute pancreatitis are frequently based on standards that are developed and validated in adult patients. Among the broad range of etiologies of pediatric acute pancreatitis in children, gallstones and biliary disease may play a greater role than previously believed. Although it is typically a benign disease in the pediatric population, complications such as pseudocysts may occur. When there are fatalities, they are usually attributed to systemic illness rather than the pancreatitis itself. Improvements in diagnostic and imaging methods and growing awareness cannot account for the recent increases in the observed incidence of pediatric acute pancreatitis.

The objective of this study is to examine the effects of developmental stage on amylase expression in the mosquitofish (Gambusia affinis holbrooki, Poeciliidae). Expression was characterized in terms of amylase activity and amount of amylase protein in five developmental stages: early, mid, and late embryos, 5-day-old juveniles, and adults. Two measures of activity were used: a starch-iodine assay, which measures the change in substrate, and the dinitrosalicyclic acid (DNSA) assay, which measures the change in product. To measure changes in the amount of amylase, the enzyme-linked immunosorbent assay (ELISA) was used. Highest activity and amount was observed in the adult stage. In general, both increased with development. While the two activity measures were positively correlated, these were only weakly correlated with the amount of amylase. Possible reasons for these weak correlations between amylase activity and amount are discussed.

Enzymatic and immunologic methods were used to study amylase expression in amniotic fluid and human pancreatic tissue from fetuses of various gestational ages. A starch-coated slide assay was used to quantitate amylase activity in amniotic fluids, and samples with activity were studied by electrophoresis to determine the presence of salivary amylase (Amy1) and pancreatic amylase (Amy2) isozymes. Immunohistochemical studies were performed with both a rabbit anti-human Amy1 antibody and a murine anti-human Amy2 antibody (Amy2/SP2/1). Amy2/SP2/1 was used to discriminate between Amy1 and Amy2. Both Amy1 and Amy2 activities were present in amniotic fluid from 14 weeks' gestation, and immunologic activity was present in pancreatic tissue sections from 15.9 weeks' gestation.

The purpose of this article is to review recent literature on the isoenzymes of alpha amylase. Although some studies are cited from the literature of fields other than clinical biochemistry, the aim is to bring together findings that may be of interest to clinical laboratory physicians and scientists. It is hoped that this will be useful in suggesting further studies of amylase. To this end, the review is more selective than exhaustive. The review will discuss the history and chemistry alpha amylases, the measurement of amylase and amylase isoenzymes, posttranslational modifications of human amylases, and the genetics of human pancreatic and salivary amylases. Finally, we will discuss other tissue sources of amylase with emphasis on "genital" amylases and their relationship to the amylase found in serous ovarian tumors.

We have described the developmental pattern of the gastrointestinal tract under optimal conditions (i.e., low risk pregnancy and normal labor and delivery at term). The tissues do not develop simultaneously, and morphologic and functional development are not concurrent. An important consideration is the effect of suboptimal or even adverse conditions on the developmental sequence and attainment of maturity. Malnutrition during both the prenatal and postnatal periods may restrict the morphologic and biochemical development of the gastrointestinal tract. Dietary modifications have been shown to alter the developmental pattern of intestinal and pancreatic enzymes in animal models. Drugs and hormonal therapy given during pregnancy and early infancy have been known to cause developmental defects, but the specific effects on the gastrointestinal tract have not been evaluated. For further understanding of digestibility of nutrients and absorption in the perinatal period, these departures from the normal development of the gastrointestinal tract and the mechanisms by which these potential effects occur remain to be described. In view of these undetermined factors, in the case of intolerance or unavailability of milk from the natural mother, feedings should be individualized, with attention to direct measurement of enzyme concentrations, balance studies, or both, especially in the case of extreme prematurity or unusual requirements.

Composition of the amylase isozymes in the amniotic fluid and their transition with fetal age were studied by means of thin-layer acrylamide gel electrophoresis. The results indicate that amylase isozymes in the amniotic fluid were composed of a pancreatic type faint major isozyme and several salivary type isozymes consisting of an intense major and a few less intense minor bands. Characteristic changes in the pattern of these isozymes with fetal age consisted of a marked increase of the salivary type isozymes rather than of the pancreatic type isozyme. A densitometric analysis of the isozyme patterns proved that the ratio of the pancreatic type isozyme to the salivary type major isozyme was highly correlated with fetal age regardless of levels of amylase activity.