Question

Those with abetalipoproteinemia exhibit, among other things, low levels of chylomicrons in their bloodstream. Which of the following symptoms is likely caused by this metabolic disorder? A. Diarrhea or excessive watery stool B. Steatorrhea or excessive fat in the stool C. Hyperlipidemia or excessive fat in the blood stream D. Hypertriglyceridemia or elevated levels of triglycerides in the blood stream

Short answer

B. Steatorrhea or excessive fat in the stool

Step-by-step solution

Understanding Abetalipoproteinemia

Abetalipoproteinemia is a rare inherited disorder that affects the absorption and transport of fats (lipids) in the body. It leads to very low levels or absence of apolipoprotein B, a primary component of chylomicrons.

Identifying the Role of Chylomicrons

Chylomicrons are lipoproteins responsible for transporting dietary fats from the intestines to other parts of the body. Low levels of chylomicrons imply poor fat absorption and transport.

Analyzing Symptoms of Fat Malabsorption

Given that chylomicrons are crucial for fat transport, low levels due to abetalipoproteinemia would hinder fat absorption, leading to fat remaining in the intestines.

Reviewing Provided Symptoms

A. Diarrhea or excessive watery stool B. Steatorrhea or excessive fat in the stool C. Hyperlipidemia or excessive fat in the blood stream D. Hypertriglyceridemia or elevated levels of triglycerides in the blood stream

Choosing the Correct Symptom

Since low chylomicron levels hinder fat absorption, the excessive fats would be expelled through the stool. This leads to option B, Steatorrhea or excessive fat in the stool.

Key concepts

chylomicrons

Chylomicrons are essential for transporting dietary fats from the intestines to other parts of the body.
These large lipoproteins are made in the intestinal cells from consumed fats and help in delivering triglycerides, cholesterol, and fat-soluble vitamins to the lymph system and eventually into the bloodstream for distribution.

Abetalipoproteinemia is characterized by a severe deficiency of chylomicrons, which leads to poor absorption and transport of dietary fats. Without sufficient chylomicrons, fats accumulate in the intestinal cells and cannot be efficiently transported to the rest of the body.

This disruption in fat transport is a key factor in understanding the symptoms and complications associated with the disorder. Therefore, understanding chylomicrons helps in comprehending why patients with abetalipoproteinemia may experience specific metabolic issues and gastrointestinal symptoms.

fat malabsorption

Fat malabsorption occurs when the body cannot properly absorb fats from the diet.
This can lead to various digestive problems and deficiencies in vital nutrients. In the case of abetalipoproteinemia, the lack of chylomicrons means that fats consumed in the diet are not effectively absorbed into the bloodstream.

Instead, these fats accumulate within the intestine, resulting in several complications:

• Failure to thrive and weight loss due to the body not getting enough energy from fats
• Deficiencies in fat-soluble vitamins (A, D, E, and K), since these vitamins rely on fats for absorption
• Development of fatty liver due to an accumulation of fats in the liver cells

Recognizing fat malabsorption is crucial for diagnosing and managing conditions like abetalipoproteinemia, as it directly correlates with the symptoms and nutritional deficiencies observed in affected individuals.

steatorrhea

Steatorrhea is a condition characterized by the excretion of abnormal quantities of fat with the stool.
This happens because the fats are not absorbed properly in the intestine due to malabsorption issues such as those found in abetalipoproteinemia.

Symptoms of steatorrhea include:

• Greasy, foul-smelling stools
• Floating stools
• Loose and frequent bowel movements

These symptoms occur because the unabsorbed fats move through the digestive system and are eventually excreted.
The presence of steatorrhea in patients with abetalipoproteinemia is a direct result of the impairment in chylomicron formation, leading to fat malabsorption. Detecting steatorrhea can be an important diagnostic clue for healthcare providers to identify underlying issues with fat absorption and to implement appropriate dietary and medical interventions.