Turnaround times
The quoted turnaround time is from sample receipt in the laboratory, to results authorisation in the Laboratory Information Management system. The times do not include transport of specimen to the laboratory or the administrative process to print and post/email reports. Service users must allow for transport and reporting time when ordering tests.
Clinical background:
Sitosterol and campesterol are measured in the investigation of phytosterolaemia (sitosterolaemia), a rare autosomal recessive disorder of the sterol ATP binding cassette transporters ABCG5 and ABCG8. Patients with defective ABCG5 and ABCG8 have enhanced absorption and reduced bile excretion of sterols including sitosterol and campesterol. The clinical presentation of the disorder is variable but some patients develop xanthoma and premature atherosclerosis. Some have elevated LDL cholesterol. Investigation of phytosterolaemia should be considered in patients with clinical features of familial hypercholesterolaemia, in particular tendon xanthoma, but with normal serum cholesterol, or elevated cholesterol but no FH gene mutation identified.
Specimen container paediatric:
Lithium heparin plasma
Specimen container adult:
Lithium heparin plasma
Minimum volume paediatric:
1 mL blood, 0.5 mL plasma
Minimum volume adult:
2 mL blood, 1 mL plasma
Special requirements:
Protect from light. Blood sample should be centrifuged on receipt in the laboratory and the plasma separated and frozen.Please provide clinical information including details of any lipid-lowering therapy.
Transport requirements:
NUTH users: send sample to the laboratory at ambient temperature, protected from light. External hospitals: send sample to the RVI frozen and protected from light.
Interpretation :
Patients with phytosterolaemia have very high circulating levels of sitosterol and campesterol. Mildly increased sitosterol and campesterol are also found in patients with familial hypercholesterolaemia so use of the sterol/cholesterol ratio can improve the diagnostic sensitivity and specificity of the test. Exposure to light may cause degradation of sterols. A diagnosis of phytosterolaemia should be confirmed by gene mutation analysis.
Reference ranges :
| Reference Ranges for Sterols in Plasma and Serum | |||
| Sterol | Adults (18 years and over) | Paediatrics (under 18 yrs) | Units |
| Cholesterol | 2500 – 7200 | 1900 – 4900 | µmol/L |
| Sitosterol | Less than 8.7 | Less than 8.5 | µmol/L |
| Campesterol | Less than 13.7 | Less than 10.4 | µmol/L |
| Reference Ranges for Sterol/Cholesterol ratios | |||
| Sterol ratio | Adults (18 years and over) | Paediatrics (under 18 yrs) | Units |
| Sitosterol/cholesterol | 0.21 – 1.90 | 0.05 – 1.70 | µmol/mmol |
| Campesterol/cholesterol | 0.26 – 2.80 | 0.20 – 2.84 | µmol/mmol |
Other info :
Serum or EDTA plasma are also acceptable, but must be protected from light.