Test Overview
Test Methodology

Gas Chromatography/Mass Spectrometry (GC/MS)

Test Usage

Diagnosis of Smith-Lemli-Opitz syndrome (7-dehydrocholesterol reductase deficiency).

Reference Range *

7-Dehydrocholesterol: < or = 2.0 mg/L
8-Dehydrocholesterol: < or = 0.3 mg/L

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Test Details
Days Set Up
Tuesday, Friday
Analytic Time

4 - 10 days

Soft Order Code
MiChart Code
Smith/Lemli/Opitz (7-DHC & 8-DHC)(Sendout)
  • 8-Dehydrocholesterol (8-DHC)
  • 7-Dehydrocholesterol (7-DHC)
  • SLO (Smith-Lemli-Opitz) Syndrome
  • SLO
  • Smith-Lemli-Opitz Screen,Plas.
Reference Laboratory
Mayo SLO (81595)
Special Testing
Specimen Requirements
Collection Instructions

Collect specimen in a green top tube from a fasting patient (12 hour fast or just before next feeding for infants). Centrifuge, aliquot serum into a plastic vial, send to Specimen Processing frozen

Special Handling

Fasting specimen.

Alternate Specimen
Lavender top (EDTA), pearl white top (EDTA/gel tubes), yellow top (ACD A) or yellow top (ACD B)
Normal Volume
0.5 mL plasma
Minimum Volume
0.2 mL plasma
Storage Temperature
Frozen preferred, ambient or refrigerated acceptable
Additional Information

Test sent to Mayo Clinic Laboratories.

CPT Code
Fee Code