Preferred Sample Type


Suitable Specimen Types

Li Hep Plasma


Specimen Volume

2 mL blood

Specimen Transport

First Class Post to reference laboratory

Sample Preparation

Lithium heparin plasma

Turnaround Time

3 weeks

Sample Processing In Laboratory

No special requirements for transporting sample to the laboratory

Sample Stability

store frozen prior to shipment to referral laboratory

General Information

7-dehydrocholesterol is a precursor of cholesterol biosynthesis. Elevated levels of 7-dehydrocholesterol and low levels of cholesterol are found in patients with Smith Lemli Opitz (SLO) syndrome. This is an autosomal recessive disorder characterised by dysmorphic features with abnormalities of limbs and genitalia. The primary defect in SLO is presumed to be due to a deficiency of delta-7-dehydrocholesterol reductase. Measurement of 7-dehydrocholesterol is particularly important in patients suspected of having SLO when cholesterol levels are low-normal, as high levels of 7-dehydrocholesterol may interfere with cholesterol assays.

Patient Preparation




Reference Range

Provided by Reference Laboratory


  • EQAS Scheme: Yes

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