case 6

[md90]

A 19-year-old female college student comes to the university health clinic complaining of muscle aches. She recently began an exercise program in an attempt to lose the 6-8 kg (15lbs) that she had gained over the past year. After her first day of weight lifting, however, she became extremely sore. Several hours later, her urine was the color of "cherry soda pop." Physical examination is unremarkable. Laboratory tests reveal a serum creatine kinase level of 93,970 IU/L. Urinalysis is negative for blood and positive for myoglobin.

1. What is the most likely diagnosis?
2. What is the biochemical defect in this condition?
3. What are the most likely findings on biopsy of the liver and muscle?
4. After the patient completes an exercise tolerance test, her lactic acid levels do not increase normally. Why?
5. What is the most appropriate treatment for this condition?

[MDiva]

1. What is the most likely diagnosis?
2. What is the biochemical defect in this condition?
3. What are the most likely findings on biopsy of the liver and muscle?
4. After the patient completes an exercise tolerance test, her lactic acid levels do not increase normally. Why?
5. What is the most appropriate treatment for this condition?


1. Paroxysmal Nocturnal Hemoglobinuria (aka "marching disease")
2. something on the RBC membrane is missing--forgot:confused: causing lysis of RBCs
3. ischemia
4. defective RBCs
5. bone marrow transplant

Now I gotta go look this up! Amazing how much we learn and how much we really retain. Thanks for the questions, md90!!!

[md90]

1. Paroxysmal Nocturnal Hemoglobinuria (aka "marching disease")
2. something on the RBC membrane is missing--forgot:confused: causing lysis of RBCs
3. ischemia
4. defective RBCs
5. bone marrow transplant

Now I gotta go look this up! Amazing how much we learn and how much we really retain. Thanks for the questions, md90!!!

MDiva, re-read the question...; the question does not state that it was positive for iron (hemogloblin); not having difficulty in breathing during the day or night... look for the 'KEYS'... as goljan states.. they will give it away in the stem of the question...

KEYS TO THE QUESTION: muscle aches, after exercising becoming sore, urine is "cherry soda pop"; serum creatine kinase increased, urine positive for myoglobin...; Does this help?

[MDiva]

Considering the keys....ok, I was in the wrong neck of the woods! This is a muscle problem, not hematological...dermatomyositis.

[md90]

Considering the keys....ok, I was in the wrong neck of the woods! This is a muscle problem, not
hematological...dermatomyositis.

This disease is really the "true" glycogen diseases...

1. What is the most likely diagnosis?
McArdle's disease
2. What is the biochemical defect in this condition?
deficiency of muscle glycogen phosphorylase... is the glycogen formation that is at fault, but the breaking it down of it at the alpha-1,4-glycosidic bonds... so that glucose-1-phosphate can be released... (remember the body needs the energy while exercising.. and uses anaerobically..
3. What are the most likely findings on biopsy of the liver and muscle? there is nothing wrong with the liver; it is the muscle.. the enzyme is found only in muscle... there is an accumulation of glycogen;
4. After the patient completes an exercise tolerance test, her lactic acid levels do not increase normally. Why? lactic acid is the product of anaerobic glycolysis... therefore if there is a problem, there is a defect in either the metabolism of glycogen or glucose to lactate...
5. What is the most appropriate treatment for this condition? we need glucose so how do we get it? how about drinking fluids that contain glucose or sugars that can be broken down to glucose.... such as gatorade (sucrose---glucose); remember Goljan stating that fructose is not a good one... but can't remember the details (have to look it up)...