Determination of cholesteryl sulphate by isotope dilution-mass spectrometry for diagnosis of steroid sulphatase deficiency.
A specific and accurate method for determination of cholesteryl sulphate in serum based on isotope dilution-mass spectrometry has been developed. 2H-labelled cholesteryl sulphate was synthesized and used as internal standard. After addition of the internal standard to serum, the cholesteryl sulphate is extracted with butanol and purified by thin-layer chromatography. The material is then solvolysed, converted into trimethylsilyl ether, and analysed by combined gas chromatography-mass spectrometry. The ratio between unlabelled and labelled cholesterol is determined by selected ion monitoring of the ions at m/e 458 (corresponding to the molecular ion of derivative of unlabelled cholesterol) and m/e 465 (corresponding to the molecular ion of derivative of 2H7-labelled cholesterol). The concentration of cholesteryl sulphate is calculated with use of a standard curve. The coefficient of variation of the method was found to vary between 4% and 9% in different concentration ranges. Nine healthy male infants (age range, 1-3 yr) had concentrations of cholesteryl sulphate varying between 0.2 and 11 mumol/l (mean, 3.8 mumol/l). A boy with suspected steroid sulphatase deficiency had a concentration of cholesteryl sulphate of 69 and 64 mumol/l at the age of 12 and 18 months, respectively.
D000328:Adult; D002250:Carbon Radioisotopes; D002675:Child, Preschool; D002788:Cholesterol Esters / Q000097:blood*; D003903:Deuterium; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007057:Ichthyosis / Q000175:diagnosis; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D013058:Mass Spectrometry; D011247:Pregnancy; D011248:Pregnancy Complications / Q000175:diagnosis*; D011296:Prenatal Diagnosis; D011865:Radioisotope Dilution Technique; D043266:Steryl-Sulfatase; D013429:Sulfatases / Q000172:deficiency*
D002250:Carbon Radioisotopes; D002788:Cholesterol Esters; D003903:Deuterium; D013429:Sulfatases; D043266:Steryl-Sulfatase; C007045:cholesteryl sulfate