Problem 9 - Clinical Chemistry

Question

All of the following are characteristic of von Gierke disease EXCEPT a. Hypoglycemia b. Hypolipidemia c. Increased plasma lactate d. Subnormal response to epinephrine

Step-by-Step Solution

Answer

b. Hypolipidemia

Step 1: Understand Von Gierke Disease

Von Gierke disease is a type of glycogen storage disease that affects the body's ability to break down glycogen into glucose.

Step 2: Identify Symptoms

Common symptoms of Von Gierke disease include hypoglycemia, increased plasma lactate, and a subnormal response to epinephrine.

Step 3: Eliminate Incorrect Symptoms

Hypoglycemia (low blood sugar), increased plasma lactate, and a subnormal response to epinephrine are all characteristic of Von Gierke disease. Hypolipidemia (low lipid levels in the blood) is not a characteristic of this disease.

Step 4: Choose the Correct Answer

The correct answer is b. Hypolipidemia.

Key Concepts

Understanding Glycogen Storage Disease

Glycogen storage diseases (GSDs) are a group of inherited metabolic disorders that occur due to enzyme defects. These enzymes are critical for glycogen synthesis or breakdown in the body. In people with GSDs, glycogen, an important energy reserve, builds up in tissues or has an abnormal structure because it cannot be processed correctly. There are several types of GSDs, each affecting different enzymes and having different symptoms. Von Gierke disease, or GSD type I, is the focus here. It primarily affects the liver and kidneys, leading to several metabolic complications.

Hypoglycemia in Von Gierke Disease

Hypoglycemia refers to low blood sugar levels and is a hallmark symptom of Von Gierke disease. Normally, when blood sugar levels drop, the liver releases glucose from glycogen stores to stabilize them. However, in Von Gierke disease, the enzyme glucose-6-phosphatase is deficient or absent. This deficiency prevents the liver from converting glycogen to glucose, resulting in persistently low blood glucose levels.
Symptoms of hypoglycemia can include:

• Irritability
• Sweating
• Paleness

If untreated, hypoglycemia can be severe, potentially leading to seizures or loss of consciousness.

Increased Plasma Lactate Levels

In Von Gierke disease, the inability to break down glycogen effectively also affects how our bodies manage lactate. Usually, lactate is converted back to glucose in the liver. But due to the enzyme deficiency in this disease, lactate accumulates in the blood, leading to hyperlactatemia. Raised lactate levels can cause conditions such as acidosis, where the body fluids contain too much acid.
Symptoms of increased plasma lactate include:

• Fatigue
• Muscle cramps
• Breathing difficulties

Regular monitoring and dietary adjustments are crucial to manage lactate levels effectively.

Subnormal Response to Epinephrine

Epinephrine, also known as adrenaline, typically signals the liver to release glucose during stress or low blood sugar situations. For individuals with Von Gierke disease, the liver cannot respond properly to epinephrine due to the deficient glucose-6-phosphatase enzyme. This results in a subnormal or lackluster glucose response during stress or hypoglycemic events.
This blunted response can leave individuals unprepared for sudden drops in blood sugar, making constant vigilance and management efforts critical. Such efforts include:

• Frequent meals
• Snack plans, especially overnight
• Regular medical consultations