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Test ID: SLO    
Smith-Lemli-Opitz Screen, Plasma

Method Description Describes how the test is performed and provides a method-specific reference

The plasma specimen is hydrolyzed with 2% KOH/ethanol for 1 hour at 65 degrees C. The compounds are then extracted with hexane, followed by evaporation to dryness under nitrogen. Using 50:50 50 bis-(trimethylsilyl) trifluoroacetamide (BSTFA:pyridine), the sterols are derivatized to generate trimethylsilyl ethers. The derivatized specimens are then transferred to gas chromatography (GC) sampling vials and 2 mcL are injected onto a HP-5 capillary column. Selected ion-monitoring electron impact gas chromatography-mass spectrometry is used as qualitative screening. When 7-dehydrocholesterol (7-DHC) and 8-DHC are detected in abnormal concentrations (>2 mcg/mL), quantitative analysis is performed via gas chromatography with flame ionization detection using epi-coprostanol as the internal standard.(Kelley RI: Diagnosis of Smith-Lemli-Opitz syndrome by gas chromatography/mass spectrometry of 7-dehydrocholesterol in plasma, amniotic fluid and cultured skin fibroblasts. Clin Chim Acta 1995;236:45-58)

Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.

Varies; Batched 1 time per week

Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.

3 days

Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result

9 days

Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

1 month

Performing Laboratory Location The location of the laboratory that performs the test

Rochester