Alberta Precision Laboratories

--- Query Results ---

Organization:

Alberta Precision Laboratories

Message Alert:

PLEASE NOTE: This Test Directory is in an interim state and due to changes pertaining to the DynaLIFE transition, performing site for routing has not been updated. Please refer to Laboratory Information System for appropriate routing.

Test Name/Synonym:

7-Dehydrocholesterol, Blood (Synonyms: SLO, Smith-Lemli-Opitz Syndrome)

Clinical Indications:

This test is for the investigation of Smith-Lemli-Opitz syndrome, and the level of 7-dehydrocholesterol is reported along with the cholesterol level.

Test Includes:

7-dehydrocholesterol, cholesterol

Ordering Alert:

This test is considered specialty testing; this test will be cancelled if sufficient clinical justification is not provided.
Requests for testing should be supported by a high index of clinical suspicion specific to the disorder in question.

Collection Alert:

Hours fasting must be indicated. Recommend collection following a minimum four hour fast or just before next feeding for newborns.
Specimens collected from non-fasting patients will be accepted for testing.

LABID (Connect Care):

LAB4002

Test Code:

CALGARY ZONE	BGLBL; IN THE BGL TEST NAME PROMPT ENTER DEHYDROCHOLES
CENTRAL ZONE	MISC
NORTH ZONE	MISC
SOUTH ZONE	7DEH

Specimen Type:

Blood

Primary Container:

Green top – Sodium heparin (no gel)

Alternate Containers:

Green top – Lithium heparin (no gel)
Red top – Non-additive (no gel)

Minimum Collection Volume:

0.5 mL plasma or serum

Specimen Collection Requirements:

Collect one sodium heparin (or alternate) tube.
Indicate length of fast, or time of last feeding on the requisition (with collection time).

Test Resources:

Submit request using the applicable requisition or Connect Care online order entry:

Biochemical Genetics Laboratory Requisition

Please ensure all required information, including patient's clinical history/indication, is provided on the requisition.

Stability and Storage:

Frozen: plasma or serum aliquot

Processing:

For ALL collection locations except for Alberta Children’s Hospital (ACH):
1. Centrifuge; If red top tube is collected, allow to fully clot prior to centrifugation.
2. Transfer plasma or serum to aliquot tube.
3. Write "NaHep", "LiHep" or "Red Top" on the aliquot tube label.
4. Freeze aliquot tube.

If collected at ACH outpatient Lab:

The primary tube can be put on ice (ensure not to freeze sample) or refrigerated for routine pick-ups between 08:30 to 14:30, Monday through Friday (excluding holidays).
If specimen is collected after 14:30, process sample as described above.

Transportation:

Transport frozen specimens on dry ice.
Samples must not thaw during transport.

Method:

Gas chromatography-mass spectrometry (GC-MS)

Method and Interpretation of Results:

7-dehydrocholesterol and cholesterol are detected following derivatization (i.e., silylation) using a gas chromatography-mass spectrometry (GC-MS) stable isotope dilution (SID) method with deuterium-labeled internal standards.

Elevated 7-dehydrocholesterol (7-DHC) is highly suggestive of a biochemical diagnosis of Smith-Lemli-Opitz (SLO). Mild elevation of 7-dehydrocholesterol can also be detected in patients with hypercholesterolemia and in patients on certain medications (e.g., haloperidol, aripiprazole, trazodone).

Routine Turn Around Time:

45 days

Testing Schedule:

Monthly

Reference Interval:

Metabolites (plasma/serum)	Age	Concentration	Units
7-Dehydrocholesterol		0.4 to 4.0	(µmol/L)
Cholesterol	Less than 7 days	1.0 to 3.9	(mmol/L)
Cholesterol	7 days to 3 months	1.3 to 4.2	(mmol/L)
Cholesterol	3 to 18 months	1.8 to 5.0	(mmol/L)
Cholesterol	18 to 36 months	2.0 to 5.2	(mmol/L)
Cholesterol	3 to 16 years	2.0 to 5.3	(mmol/L)
Cholesterol	Greater than 16 years	2.0 to 5.6	(mmol/L)

Testing Area:

Biochemical Genetics

Performing Site:

Alberta Children's Hospital

Additional Test Information:

For priority turn-around contact Biochemical Genetics South Laboratory.

Contact Comments:

Biochemical Genetics 403-955-7379

Last Updated On:

Monday, April 17, 2023

Date of Last Review:

Aug 1 2022 12:00AM