Medical Blog

WDHA Syndrome

Introduction
Background

In 1957, Priest and Alexander reported a patient with peptic ulcer, diarrhea, hypokalemia, and an islet cell tumor.1 However, the first complete description of the syndrome of watery diarrhea, hypokalemia, and achlorhydria (ie, WDHA syndrome) was provided by Verner and Morrison in 1958.2 This rare condition is characterized by severe watery diarrhea caused by oversecretion of vasoactive intestinal peptide (VIP) from non–beta pancreatic islet cells. Patients usually have elevated VIP levels and require frequent hospitalizations for dehydration and/or hypokalemia. Because this condition resembles cholera, Matsumoto and colleagues (1966) suggested the alternative term pancreatic cholera.3  Read more…

Zollinger-Ellison Syndrome

Introduction
Background

Zollinger-Ellison syndrome (ZES) is caused by a non–beta islet cell, gastrin-secreting tumor of the pancreas that stimulates the acid-secreting cells of the stomach to maximal activity, with consequent gastrointestinal mucosal ulceration. ZES may occur sporadically or as part of an autosomal dominant familial syndrome called multiple endocrine neoplasia type 1 (MEN 1). The primary tumor is usually located in the duodenum, the pancreas, and abdominal lymph nodes, but ectopic locations have also been described (eg, heart, ovary, gall bladder, liver, kidney).
Pathophysiology Read more…

Hepatitis E

Introduction
Background

Hepatitis E virus (HEV) is an enterically transmitted infection that is typically self-limited. It is spread by fecally contaminated water within endemic areas. Outbreaks can be epidemic and individual. Hepatitis E has many similarities with hepatitis A. Hepatitis E infection has recently been associated with chronic hepatitis in solid organ-transplant recipients.1  Read more…

Hepatitis A

Introduction
Background

One of the more common causes of acute hepatitis is hepatitis A virus (HAV). The hepatitis A virus was isolated by Purcell in 1973. Since the application of accurate serologic investigations in the 1980s, the epidemiology, clinical manifestations, and natural history of hepatitis A have become apparent.

The relative frequency of the hepatitis A virus as a cause of acute hepatitis has declined in Western societies, while in contrast, notification of individual cases has increased, primarily as a result of improved reporting and diagnostic techniques. The nadir of reported cases was in 1987.

Improvements in hygiene, public health policies, and sanitation have had the greatest impact on this disease, and vaccination and passive immunization have successfully led to some reduction in illness in high-risk groups. Reduced encounters with the hepatitis A virus at a young age have resulted in both a decline in herd immunity and a change to the epidemiology of the illness, with increases in the mean age of occurrence of illness attributed to acute hepatitis A virus infection in Western societies. Although this phenomenon may lay a framework for potential epidemics in the future, public health policies and newly implemented immunization practices are likely to reduce this potential. Read more…

Lactose Intolerance

Introduction
Background

Lactose intolerance is a common disorder and is due to the inability to digest lactose into its constituents, glucose and galactose, secondary to low levels of lactase enzyme in the brush border of the duodenum. Lactase deficiency is the most common form of disaccharidase deficiency. Enzyme levels are highest shortly after birth and decline with aging, despite a continued intake of lactose. Within the animal world, nonhuman mammals usually lose the ability to digest lactose as they reach adulthood. Some populations of the human species, including those of Asian, South American, and African descent, have a propensity for developing lactase deficiency. By contrast, races descended from northern Europe or from the northwestern Indian subcontinent are likely to retain the ability to absorb lactose into adulthood. Read more…

Ileus

Introduction
Background

After abdominal surgery, a normal physiological ileus occurs. This type of ileus spontaneously resolves within 2-3 days after sigmoid motility returns to normal. However, the terms postoperative adynamic ileus or paralytic ileus are defined as ileus of the gut persisting for more than 3 days following surgery.1

Ileus occurs from hypomotility of the gastrointestinal tract in the absence of a mechanical bowel obstruction. This suggests that the muscle of the bowel wall is transiently impaired and fails to transport intestinal contents. This lack of coordinated propulsive action leads to the accumulation of both gas and fluids within the bowel. Although ileus has numerous causes, the postoperative state is the most common scenario for ileus development. Frequently, ileus occurs after intraperitoneal operations, but it may also occur after retroperitoneal and extra-abdominal surgery. The longest duration of ileus is noted to occur after colonic surgery.2, 3
Read more…

Hiatal Hernia

Introduction
Background

A hiatal hernia occurs when a portion of the stomach prolapses through the diaphragmatic esophageal hiatus. Although the existence of hiatal hernia has been described in earlier medical literature, it has come under scrutiny only in the last century or so because of its association with gastroesophageal reflux disease (GERD) and its complications. By far, most hiatal hernias are asymptomatic and are discovered incidentally. On rare occasion, a life-threatening complication, such as gastric volvulus or strangulation, may present acutely. Read more…

Inflammatory Bowel Disease

Introduction
Background

Inflammatory bowel disease (IBD) is an idiopathic disease, probably involving an immune reaction of the body to its own intestinal tract. The 2 major types of IBD are ulcerative colitis and Crohn disease. As the name suggests, ulcerative colitis is limited to the colon; Crohn disease can involve any segment of the gastrointestinal tract from the mouth to the anus.

Although ulcerative colitis and Crohn disease have significant differences, many (but not all) of the treatments available for one are also effective for the other. Likewise, both diseases share many extraintestinal manifestations, although some of these tend to occur more commonly with one disease or the other. Read more…

Shigellosis

Introduction
Background

Shigella organisms cause bacillary dysentery, a disease that has been described since early recorded history.
Pathophysiology

Shigella species (eg, Shigella dysenteriae, Shigella flexneri, Shigella sonnei, Shigella boydii) are aerobic, nonmotile, glucose-fermenting, gram-negative rods that are highly contagious, causing diarrhea after ingestion of as few as 180 organisms. Read more…

Villous Adenoma

Introduction
Background

Adenomatous polyps are, by definition, neoplastic. Although benign, they are the direct precursors of adenocarcinomas and follow a predictable cancerous temporal course unless interrupted by treatment. They can be either pedunculated or sessile. Polyps are generally asymptomatic but may occasionally ulcerate and bleed; uncommonly, they may result in obstruction if very large. Adenomas are divided into 3 subtypes based on histologic criteria, as follows: (1) tubular, (2) tubulovillous, and (3) villous. According to World Health Organization (WHO) criteria, villous adenomas are composed of greater than 80% villous architecture. Tubular adenomas are encountered most frequently (80-86%). Tubulovillous adenomas are encountered less frequently (8-16%), and villous adenomas are encountered least frequently (5%). Read more…