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:
Cholestanol, an intermediate in the synthesis of bile acids from cholesterol, is measured in plasma in the investigation of the rare inherited metabolic disorder cerebrotendinous xanthomatosis (CTX, sterol 27-hydroxylase deficiency). Patients with CTX usually have adult-onset progressive neurological dysfunction, tendon xanthomas, premature atherosclerosis, osteoporosis and respiratory insufficiency with normal cholesterol. Some patients present early in life with cholestatic jaundice which resolves, mental retardation and cataracts. Clinical features of the disorder are very variable and the diagnosis is often delayed.
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:
Blood sample should be centrifuged on receipt in the laboratory and the plasma separated and frozen.
Transport requirements:
NUTH users: send sample to the laboratory at ambient temperature.
External hospitals: send sample to the RVI frozen and protected from light.
Interpretation:
Patients with CTX have very high circulating levels of cholestanol. Mildly increased cholestanol is 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 CTX should be confirmed by gene mutation analysis.
Reference ranges:
Cholestanol 12.5mol/L (18 years or over), 15.7mol/L (18 years)
Cholestanol/cholesterol 1.00 – 2.70 mol/mmol (18yrs or over), 1.14 – 3.34 mol/mmol (18 years).
Other info:
Serum or EDTA plasma are also acceptable, but must be protected from light.