Pancreatic disease, exocrine

A number of laboratory tests are available to measure exocrine function in the investigation of pancreatic insufficiency (most commonly caused by cystic fibrosis in children and chronic pancreatitis in adults). Tests fall into two categories, invasive and noninvasive. Invasive tests require GI, intubation to collect pancreatic samples noninvasive tests (or tubeless tests ) were developed to avoid intubation, which is uncomfortable for the patient, time-consuming, and therefore expensive. Noninvasive tests are simpler and cheaper to perform, but in general they lack the sensitivity and specificity of the invasive tests, particularly for the diagnosis of mild pancreatic insufficiency. It is important to recognize that biochemical tests have a limited clinical application in the diagnosis of pancreatic disease because of either the complexity of the invasive tests or the inadequate... 

Malabsorption. Steatorrhoea caused by exocrine pancreatic disease or biliary obstruction can cause vitamin D deficiency. 

Uncommon causes of diabetes (1% to 2% of cases) include endocrine disorders (e.g., acromegaly, Cushing s syndrome), gestational diabetes mellitus (GDM), diseases of the exocrine pancreas (e.g., pancreatitis), and medications (e.g., glucocorticoids, pentamidine, niacin, and a-interferon). 

Pearson syndrome [24] A refractory sideroblastic anemia, with variable neutropenia and thrombocytopenia, vacuolization of marrow precursors, and exocrine pancreatic dysfunction. Severe transfusion-dependent macrocytic anemia begins in early infancy (before 1 year) and the disease is fatal before 3 years in 62% of cases. Large-scale heteroplasmic deletions/duplications of mtDNA are constantly observed in affected and nonaffected organs. 

It is important to keep in mind, however, that not all patients with chronic pancreatitis develop clinical pancreatic exocrine insufficiency approximately 25% of patients still have sufficient exocrine function after 25 years of disease. On the other hand, it is also important to note that 10%-15% of patients with chronic pancreatitis have primary painless disease in these patients, pancreatic exocrine insufficiency may be the first (and possibly only) clinical manifestation. Thus, the absence of pain or a history of pancreatitis does not exclude the diagnosis (DiMagno et al., 1993). 

Fecal elastase 1 concentration can be measured by an ELISA test kit using an antibody specific for the human enzyme pancreatin supplements do not interfere with this pancreatic function test and need not be discontinued. Although measurement of fecal elastase 1 excretion appears to be somewhat more sensitive than fecal chymotrypsin, its specificity and positive predictive value are similarly low, and falsepositive results can be expected in patients with intestinal diseases. Conversely, mild-to-moderate stages of pancreatic exocrine insufficiency cannot be diagnosed reliably. 

Measurement of stool weight and quantitative fecal fat excretion on three consecutive days during a balanced diet are common screening tests for both pancreatic insufficiency and other pathologies that result in malabsorption. However, these tests are insensitive and nonspecific for pancreatic malfunction Steatorrhea occurs only after loss of more than 90% of exocrine parenchyma, and other causes of malabsorption (e.g., celiac sprue or Crohn s disease) may also induce abnormal fecal fat excretion of more than 7 g/day or more than 5 g/100 g. 

The test is valid for diagnosing severe pancreatic exocrine insufficiency but has the sensitivity limitations described above with respect to detecting mild impairment of pancreatic function. Conversely, despite the inclusion of the control test, false-positive results may occur in patients with intestinal and biliary diseases, as well as following gastric resection or Yen-Roux procedures. In the latter patients, intraluminal lack of pancreatic enzymes (despite normal secretory... 

DiMagno EP, Layer P Human exocrine pancreatic enzyme secretion, in Go VL (ed) The Pancreas Biology, Pathobiology and Diseases. Raven Press, New York, 1993, pp. 275-300. 

Elevation of serum copper is found in cholestasis, obstructive jaundice, primary biliary cholangitis, malignant tumours, kwashiorkor, exocrine pancreatic insufficiency, during the last trimenon of pregnancy and after administration of oestrogens. A decrease in serum copper is typical of Wilson s disease. In some rare cases, it is caused by familial benign hypocupraemia and nutritional deficiency in neonates. 

Cystic fibrosis is the most common lethal genetic disease among the white population of the United States. Eccrine and exocrine gland function are affected. Pulmonary disease and pancreatic insufficiency frequently occur. Food, particularly fats and proteins, may be only partially digested, and nutritional deficiencies result. 

THE PANCREAS DISEASES AND ASSESSMENT OP EXOCRINE PANCREATIC FUNCTION... 

The clinical presentation of CP varies depending on the etiology of the disease, the severity of the inflammatory process, and the extent of irreversible damage to the pancreas (Table 39-6). " The classic features of CP are abdominal pain, malabsorption, weight loss, and diabetes. Most alcoholic patients have chronic pain, while others have intermittent attacks or painless pancreatitis. Abstinence from ethanol may provide relief from pain, but does not prevent exocrine... 

Complete agenesis of the pancreas is usually incompatible with life. Therefore, pancreatic aplasia or hypoplasia is uncommon in humans. Patients with pancreatic hypoplasia will have a normal development of the pancreas in size and shape but later in life will have a replacement of the glandular elements with fatty tissue. Some of these patients will present with an abnormal exocrine pancreatic insufficiency and normal endocrine function. Children with syndromes such as Schwachman-Diamond, Beckwith-Wiedemann, polysplenia bilobed lungs, and congenital heart disease have a higher relative risk of hypoplasia of the pancreas (Gazelle et al. 1998). 

On US, the pancreas with CF is characteristically of an echogenic texture secondary to fatty infiltration (Fig. 4.17). An enlarged pancreas may be seen initially with a subsequent atrophy later in life. Pancreatic duct dilatation and calcifications may be seen. Small cysts (anechoic areas) without vascular communication can be identified. Although a hyperechogenic pancreas is very typical of CF, some other diseases such as Schwachman-Diamond syndrome (exocrine pancreas insufficiency associated with bone marrow dysfunction, cyclic neutropenia, metaphyseal diastasis and growth retardation), hemosiderosis, chronic pancreatitis, and administration of steroids may also reveal this feature (Feigelson et al. 2000). 

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