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Test ID: STER Sterols, Plasma

Reporting Name

Sterols, P

Useful For

Investigation of possible desmosterolosis (desmosterol reductase deficiency), cerebrotendinous xanthomatosis, lathosterolosis, and sitosterolemia

Specimen Type

Plasma


Necessary Information


Patient's age and sex are required.



Specimen Required


Collection Container/Tube:

Preferred: Green top (sodium heparin)

Acceptable: Lavender top (EDTA), pearl white top (EDTA/gel tubes), yellow top (ACD A) or yellow top (ACD B)

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL

Collection Instructions: Centrifuge specimen and aliquot plasma. Send plasma frozen.


Specimen Minimum Volume

0.2 mL

Specimen Stability Information

Specimen Type Temperature Time
Plasma Frozen (preferred) 90 days
  Refrigerated  90 days

Reference Values

DESMOSTEROL

0.0-2.0 mg/L

 

LATHOSTEROL

0.0-3.0 mg/L

 

CAMPESTEROL

0.0-7.0 mg/L

 

SITOSTEROL

0.0-5.0 mg/L

 

CHOLESTANOL

0.0-5.0 mg/L

Day(s) and Time(s) Performed

Thursday; 8 a.m.

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

82542

LOINC Code Information

Test ID Test Order Name Order LOINC Value
STER Sterols, P In Process

 

Result ID Test Result Name Result LOINC Value
50499 Desmosterol 75739-3
50500 Lathosterol 75740-1
50501 Campesterol 75738-5
50502 Sitosterol 75741-9
113381 Cholestanol In Process
29942 Interpretation 59462-2
29944 Reviewed By No LOINC Needed

Clinical Information

Cholesterol plays an essential role in many cellular and developmental processes. In addition to its role as a membrane lipid, it is the precursor to numerous molecules that play an important role in cell growth and differentiation, protein glycosylation, and signaling pathways. The biosynthesis of cholesterol and its subsequent conversion to other essential compounds is complex, involving a number of intermediates and enzymes. Disorders that result from a deficiency of these enzymes lead to an accumulation of specific intermediates and inhibit the formation of important biomolecules. Clinical findings common to cholesterol biosynthesis disorders include congenital skeletal malformations, dysmorphic facial features, psychomotor retardation, and failure to thrive.

 

Desmosterolosis (desmosterol reductase deficiency) is a very rare disorder of cholesterol biosynthesis with a clinical phenotype similar to that of Smith-Lemli-Opitz (SLO) syndrome (7-dehydrocholesterol reductase deficiency). To date, less than 10 cases of desmosterolosis have been described. Its biochemical marker is the elevation of desmosterol in plasma, tissue, and cultured cells.

 

Another very rare disorder of cholesterol biosynthesis is lathosterolosis caused by mutations in SC5DL (sterol 3-beta-hydroxysteroid-delta-5-desaturase). Less than 5 patients have been described to date, but the phenotype appears to be characterized by dysmorphic features, multiple congenital anomalies including those of limb and kidney, intellectual disability, and liver disease. Biochemical abnormalities include elevated lathosterol and transaminases, hyperbilirubinemia, and absent 7-dehydrocholesterol.

 

Sitosterolemia is a rare autosomal recessive disorder caused by mutations in the ATP-binding cassette (ABC) transporter genes, ABCG5 and ABCG8, which abnormally enhance the absorption of plant sterols and cholesterol from the intestines. Patients often present with hematologic abnormalities and tendon and tuberous xanthomas as well as premature coronary artery disease. A biochemical diagnosis of sitosterolemia is made by documenting elevations of the plant sterols sitosterol and campesterol in plasma or serum.

 

Cerebrotendinous xanthomatosis (CTX), also known as 27-hydroxylase deficiency, is an autosomal recessive sterol storage disease causing accumulation of cholestanol and cholesterol in most tissues and markedly increased levels of cholestenol in serum. Clinical symptoms, which are variable, develop gradually and can include early chronic diarrhea, followed by bilateral cataracts, tuberous and tendon xanthomas, early atherosclerosis, and progressive neurologic impairment such as ataxia, paraparesis, cerebellar ataxia, and dementia. CTX should be suspected in patients with tendon xanthomas and normal or elevated serum cholesterol, and considered in cases of unexplained juvenile cataracts.

Interpretation

A quantitative report of the patient's sterol profile and a Biochemical Genetics consultant's interpretation is provided for each specimen.

Clinical Reference

1. Zolotushko J, Flusser H, Markus B, et al: The desmosterolosis phenotype: spasticity, microcephaly and micrognathia with agenesis of corpus callosum and loss of white matter. European Journal of Human Genetics. 2011;19(9):942-946 doi:10.1038/ejhg.2011.74

2. Bjorkhem, I, et al: Inborn Errors in Bile Acid Biosynthesis and Storage of Sterols Other than Cholesterol. The Online Metabolic and Molecular Bases of Inherited Disease Eds. David Valle, et al: New York, NY: McGraw-Hill, 2014, Accessed April 24, 2017. Available at http://ommbid.mhmedical.com/content.aspx?bookid=971&sectionid=62638585

3. Lu K, Lee MH, Hazard S, et al: Two genes that map to the STSL locus cause sitosterolemia: genomic structure and spectrum of mutations involving sterolin-1 and sterolin-2, encoded by ABCG5 and ABCG8, respectively. Am J Hum Genet 2001 August;69(2):278-290

4. Pilo de la Fuente B, et al: Usefulness of cholestenol levels in the diagnosis and follow-up of patients with cerebrotendinous xanthomatosis. Neurologia 2011 26:397-404

5. Herman GE, Kratz L: Disorders of sterol synthesis: beyond Smith-Lemli-Optiz syndrome. Am J Med Genet C Semin Med Genet 2012;106C:301-321

Analytic Time

2 days

Method Name

Gas Chromatography-Mass Spectrometry (GC-MS)

Forms

1. New York Clients-Informed consent is required. Please document on the request form or electronic order that a copy is on file. An Informed Consent for Genetic Testing (T576) is available in Special Instructions.

2. If not ordering electronically, complete, print, and send a Neurology Specialty Testing Client Test Request (T732) with the specimen (http://www.mayomedicallaboratories.com/it-mmfiles/neurology-request-form.pdf)

Mayo Medical Laboratories | Genetics and Pharmacogenomics Catalog Additional Information:

mml-biochemical