Functional study of exocrine pancreas in idiopathic hemochromatosis, untreated and treated by venesections

Iron-Storage Disorder Presenting as Chronic Diarrhea

The involvement of the endocrine pancreas leading to bronze diabetes is well studied. However, little is known about the pathophysiology of iron dysregulation involving the exocrine pancreas. We present a unique association between the exocrine pancreas and iron dysregulation. A 45-year-old female presented with chronic diarrhea and low fecal elastase indicative of pancreatic exocrine dysfunction. MRI of the abdomen/pelvis showed iron deposition in the pancreas, suggesting an associated iron-storage disorder without features suggesting chronic pancreatitis. Association of an iron-storage disorder with pancreatic exocrine dysfunction has been reported only in one other case report. Pancreatic exocrine dysfunction can be directly associated with an iron-storage disorder that involves the pancreas. This should be included in the differential and diagnostic work-up of chronic diarrhea of unclear etiology. Based on the literature, we have highlighted the potential pathophysiology relevant to the case.

Iron metabolism and the exocrine pancreas

Although the pathophysiological mechanisms and consequences of gross derangements in iron metabolism are well known, little is known about the pathophysiological mechanisms underlying mild-to-moderate alterations in iron metabolism and their consequences. Growing evidence indicates that the exocrine pancreas has a bidirectional relationship with iron metabolism. Studies have shown alterations in circulating markers of iron metabolism, iron absorption, and intra-pancreatic iron deposition in pancreatitis. At the same time, exocrine pancreatic dysfunction has been shown in iron overload disorders. These observations reveal a compelling connection between the exocrine pancreas and iron metabolism, which are further elucidated by observations of therapeutic benefits of iron chelating agents and pancreatic enzyme replacement therapy. While the pancreas is not a major reservoir of iron in the body, better understanding of its relationship with iron metabolism may yield unexpected insights.

Biliary excretion of iron and ferritin in idiopathic hemochromatosis

The role of biliary excretion of iron and ferritin in iron overload was studied and evaluated. Ten patients with idiopathic hemochromatosis and two groups of controls (14 gallstone patients and 16 healthy subjects) were included. Liver tissue (obtained by percutaneous or operative biopsy) was investigated with light microscopy and transmission electron microscopy in combination with x-ray microanalysis. Fasting bile samples were obtained through duodenal aspiration or at cholecystectomy. Iron was determined in liver tissue and bile using atomic absorption spectroscopy, and ferritin was determined in serum and bile with a radioimmunoassay technique. All patients with hemochromatosis had iron-positive staining as seen in light microscopy. Electron microscopy showed iron-containing proteins in the lysosomes and cytosol of liver parenchymal cells, and this observation was supported by x-ray microanalysis. Hepatic iron concentration was increased about eightfold in the patients with hemochromatosis (p less than 0.001). Biliary iron concentration, expressed per millimole of bile acid, was increased about twofold (p less than 0.05) and biliary ferritin concentration about fivefold (p less than 0.001) in hemochromatosis. Four of the patients with hemochromatosis were reexamined after completed treatment with venesection; this resulted in normalized biliary concentrations of iron and ferritin. We conclude that biliary secretion of ferritin occurs in humans and that both iron and ferritin excretion are enhanced in hepatic iron overload. The apparently limited capacity of biliary iron excretion may be of importance for the hepatic iron accumulation in hemochromatosis.

Exocrine pancreatic insufficiency and idiopathic haemochromatosis

The case history of a 34-year-old patient with precirrhotic idiopathic haemochromatosis and severe chronic steatorrhoea is presented. The pancreas had a normal appearance on ultrasonography and endoscopic retrograde pancreaticography. However, pancreatic function tests revealed significant abnormalities. The pancreatic output of trypsin, amylase, lipase and bicarbonate was deficient and basal and stimulated serum pancreatic polypeptide levels were subnormal. In contrast, the oral glucose tolerance test was unimpaired. The pancreatic insufficiency had started suddenly during a summer vacation and may have had a viral aetiology. The hypothesis is advanced that in haemochromatosis the iron-laden pancreatic acinar and PP-producing cells are more susceptible to damage by viruses than normal pancreatic cells.

Pancreatic hypersecretion in liver disease

Abnormally large duodenal aspirates have been reported in a large percentage of patients with cirrhosis of the liver. The source of this fluid has been variously ascribed to the liver and/or pancreas. The present study was undertaken to clarify its source. Eleven patients with cirrhosis of the liver and one with cholestatic hepatitis underwent an intraductal secretin test during endoscopic cannulation of the pancreatic duct. Six patients with cirrhosis had pancreatic hypersecretion ranging from 7.8 to 26.0 ml/min, while three patients demonstrated low secretory flow rates. Bile flow was negligible or nonexistent in ten patients, while in two others, larger but unmeasurable amounts of bile secretion were present. This study conclusively demonstrates that pancreatic hypersecretion may occur in patients with cirrhosis during secretin stimulation. Impaired metabolism of secretin or the associated pancreatic hypersecretion of early pancreatitis may be responsible for this finding.