Analysis of Creatine Metabolites Using Gas Chromatography - Mass Spectrometry
Milda Banytė, Jurgita Songailienė, Vaidutis Kučinskas
The aim. To determine the cause of intellectual disability by quantitative creatine metabolites (creatine and guanidinoacetato) analysis by gas chromatography - mass spectrometry.
Materials and methods. Urine samples of 30 patients, who do not have metabolic disorders, according to organic acids, aminoacids and glicosamine glycans analysis, were selected and analysed. Ages of selected patients range from 1 to 15 years. The families that were consulted in Vilnius University Hospital “Santariškių Clinics” Centre for Medical Genetics in the Genetic counseling section since 2008-2010 and genetic testing of these families has not revealed the cause of intellectual disability were chosen. Creatine and guanidinoacetate concentrations in urine samples were measured by gas chromatography - masss spectrometry using SIM method.
Results. Guanidinoacetate concentrations in collected urine samples ranged from 4.93 to 109.1 mmol/mol creatinine and values were normal according to those in the publications (4-220). Creatine concentrations in col - lected urine samples in the first age group (up to 4 years) showed that creatinine level in one patient exceeded the maximum concentration. Guanidino- acetate levels of this patient were within the normal range, so the patient is suspected of creatine transporter deficiency. Creatine con cen trations in col lected urine samples in the second age group (from 4 to 12 years) ranged from 21.42 to 474.3 mmol/mol creatinine, values fit well with the normal range indicated in literature (17-720). Creatine concentrations in collected urine samples in the third age group (> 12 years) varied from 9.53 to 366 mmol/mol creatinine, values correspond well to the data in the publications.
Conclusions. Gas chromatography - mass spectrometry SIM method was used to examine 30 patients with intellectual disability urine samples, quantitative analysis of creatine and guanidino- acetate was performed. Two patients were suspected of creatine metabolism disorders: creatine transporter deficiency and AGAT deficiency.
Keywords: SIM method, creatine, guanidinoacetate, creatine transporter deficiency, AGAT deficiency.