2. Serum electrolytes. Reveal whether seizures are induced by electrolyte abnormalities (eg, Na+ and Ca2+), as well as presence of acidosis (bicarbonate) or uremia (BUN and creatinine).
3. Liver function tests. Reveal presence of hepatic failure.
4. Serum ammonia. Elevated level is associated with common inborn errors of metabolism.
5. Serum or urine drug screening. Although limited, can identify potential toxins.
6. Anticonvulsant drug levels. Obtain in patients with known seizure disorder.
7. CBC, differential, blood and urine cultures. Obtain in febrile patients or whenever sepsis or CNS infection is suspected. CBC is also helpful in evaluation of patients with sickle cell disease or suspected HUS.
8. Cerebrospinal fluid evaluation (cell count, chemistry, and culture). Obtain whenever CNS infection or sepsis is suspected.
9. Guaiac test for occult blood. Stool may reveal occult GI bleeding in patients with intussusception or HUS.
1. CT scan of head. Obtain emergently whenever increased intracranial pressure or presence of a structural lesion is suspected, especially before performing lumbar puncture to avoid risk of cerebral herniation. Obtain in all patients with altered mental status of unclear etiology.
2. Abdominal obstruction series. Helpful in screening for intussusception; if highly suspected, air or barium enema reduction is necessary.
3. Skeletal survey. Obtain in children younger than 3 years of age who may have suffered inflicted injuries or child abuse.
4. ECG. May be helpful in management of certain ingested substances or toxins.
V. Plan. Figure I-1 depicts a systematic approach to a patient with altered mental status.
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