Correct!
5. All of the above

Weakness is a nonspecific complaint which can be caused by a variety of neurological, muscular and metabolic diseases in addition to heart and/or lung diseases.

His admission laboratories were relatively unremarkable on admission but CPK, LETs and ammonia rose over 6 days to-

• Ammonia 129 mcg/dL (normal 15-45 in adults)
• CPK 6500 mcg/L (normal 10-120)
• Aspartate aminotransferase 1800 U/L (AST, normal 10-40)

Other abnormal laboratory values included-

• Creatinine 4.0 mg/dL (normal 0.6-1.2)
• Total bilirubin 4.0 mg/dL (normal 0.1 to 1.2)
• Lactate 2.3 mmol/L (normal 0.5-1.0)

He experienced episodes of hypoglycemia.  His mental status declined and he developed hypercarbic respiratory failure (pCO2 240 mm Hg) requiring intubation.

He was transferred to Banner University Medical Center-Phoenix for further evaluation.

PMH, SH and FH

• At the age of 9 he was diagnosed with Reye’s syndrome and was reported to have an elevated ammonia of 150 mcg/dL (normal 40-80 in children).
• A muscle biopsy was performed at the age of 13 which showed type 1 fiber atrophy.
• He had five previous episodes over the past three years, triggered by physical exertion (or EtOH ingestion) in which he experienced nausea, vomiting, altered mental status, sometimes associated with hypoglycemia  
• He had been diagnosed with myasthenia gravis one year prior to admission, but did not respond to corticosteroid administration.

Physical Examination

• Vitals signs: BP 133/82 mm Hg, pulse 91 beats/min, respirations 14 breaths/min while receiving mechanical ventilation, SpO2 99%.
• HEENT: temporal muscle wasting.
• Lungs: clear.
• Heart: regular rhythm without murmur.
• Abdomen: marked firm hepatomegaly 
• Neurologic: He was awake and alert. Cranial nerves appeared intact. Deep tendon reflexes were 1+ bilaterally. His muscle tone was flaccid and he could not lift his heels or head off the bed.

Laboratory Evaluation

• CPK 1692 mcg/L
• Ammonia 90 mcg/dL (normal 9.5-49 in adults)
• Lactic dehydrogenase 2796 (LDH, normal 140-280 U/L)
• Prothrombin time 13.9 secs (normal 11-13.5)

A CT scan of the abdomen was performed which showed hepatosplenomegaly with the liver infiltrated with fat (Figure 1).

Figure 1. Representative image from the abdominal CT scan. The liver is infiltrated with fat.

Which of the following is are indicated at this time? (Click on the correct answer to proceed to the third of four pages)

1. Plasma carnitine level
2. Serum ketones
3. Urine glutaric acid
4. Urine myoglobin
5. All of the above

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