A 17-year-old male presents with confusion and drowsiness for 1 day.
He has been healthy and playing in the high school basketball team for the last 2 years. His practice sessions always included 10 minutes of intense work followed by a period of rest or decreased activity. He also had complaints of dark urine which the previous doctor diagnosed as dehydration and was asked to drink more water.
He recently started a football club and has been playing football in addition to basketball. He has had oliguria for 4 days. Vitals are BP 124/86 mm of Hg, HR 85 b/min. Pupils are non dilated and reactive to light equally bilaterally. The remainder of the physical examination is within normal limits. Lab work shows:
BUN: 60 mg/dl
Creatinine: 4mg/dl
pH: 7.3
Anion gap: 20
Serum ketones: High
What is the most likely cause of the patient's diagnosis?
The answer is Mcardle's disease. The patient has been having problems like fatigue and having to take early breaks from playing. However, the patient has had increased exertion recently.
The darkened urine could be due to the occurrence of muscle damage due to the inability to consume muscle glycogen due to deficiency in enzyme myophosphorylase. This leads to leakage of myoglobin into the blood which is filtered into the kidneys. This will cause renal injury and hence the increased creatinine and BUN.
On pushing through and working out in McArdles patients, it can be observed that they start to improve in their performance due to receiving glucose and ketone bodies from the liver ("Second wind phenomenon")
The differential for this disease is medium-chain acyl CoA dehydrogenase(MCAD) deficiency which can be differentiated based on levels of ketone bodies. MCAD deficiency is associated with low ketone body levels.
Hemoglobinopathy can present in a similar fashion but would not explain the elevated serum ketones.
The patient does not have stigmata of illicit drug use, making it unlikely.
- Written by Shashi
Great explanation
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