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Three Part Question

In [a child who is neurologically healthy with an episode of unprovoked seizure] is [routine serum biochemistry helpful] at [guiding the management]

Clinical Scenario

A 7 year old child, previously healthy attends Emergency Department following first generalised tonic clonic seizure. There is no history of drug and alcohol ingestion or other provoking factors. Clinically the child is afebrile and you wonder whether serum biochemistry is nessecary for the diagnosis and management of this patient

Search Strategy

Search strategy from 1980 to Feb. 2005 was
Cochrane database of systematic review using nonfebrile unprovoked seizure AND laboratory evaluation AND children, no relevant systematic review or controlled trials of relevance
Using PubMed interface —"serum biochemistry"(MESH) AND "unprovoked seizure" (MESH) limits All child 0-18 years, English, clinical trials.
Search strategy from 1980 to Feb. 2005 was
Cochrane database of systematic review using nonfebrile unprovoked seizure AND laboratory evaluation AND children, no relevant systematic review or controlled trials of relevance
Using PubMed interface —"serum biochemistry"(MESH) AND "unprovoked seizure" (MESH) limits All child 0-18 years, English, clinical trials.

Search Outcome

There were 118 hits (6 relevant), see table.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Nypaver et al, 1992, USA	308 children (65% non-febrile)	Retrospective	Serum biochemistry performed in 40%.	No abnormal test thought to have caused seizure.	Includes febrile and recurrent seizures
Kenney, 1992, USA	241 children (155 non-febrile)	Retrospective	64% had biochemistry.	All normal.	Includes febrile and recurrent seizures
Scarfone, 2000, USA	134 children	Retrospective cohort	Serum biochemistry performed in 50%.	13% abnormal low Na , low Ca. Higher results in patient Seizures in ED. <1 month Temp <36.5	Age group infants, incl. FS
Valencia, 2003, USA	107 children	Prospective observational	Serum biochemistry performed in 54%.	14.8% abnormal. Abnormal <2 years. GI symptoms. First seizures. Change mental status.	Not all had laboratory tests

Comment(s)

Only two of the studies are prospective, however the total studies' number of patients is clinically significant. Only one of the studies assessed fully utility of laboratory testing for infants with seizures.

Clinical Bottom Line

We concluded that routine determination of serum biochemistry values in paediatric patients presenting with unprovoked seizure is unnecessary unless specific clinical data strongly suggest otherwise. Laboratory testing is recommended for non febrile seizures in infants who 1) are actively seizing in the ED, 2) have a temperature below 36.5 degrees C, or 3) are less than 1 month of age.

References

1. Nypaver MM, Reynolds SL, Tanz RR, Davis AT. Emergency department laboratory evaluation of children with seizures: dogma or dilemma? Pediatr Emerg Care. 1992;8:13-16.
2. Kenney RD. Taylor JA. Absence of serum chemistry abnormalities in pediatric patients presenting with seizures. Pediatr Emerg Care. 1992;8:65-66.
3. Scarfone RJ, Pond K. Utility of laboratory testing for infants with seizures. Pediatr Emerg Care. 2000 Oct;16(5):309-12.
4. Valencia I, Sklar E. The role of routine serum lab. tests in children presenting to the emergency dept with unprovoked seizures. Clin Pediatr (Philo). 2003 Jul-Aug 42(6):511-7.