Related Experiment Video
Updated: Jul 11, 2026

One-step Metabolomics: Carbohydrates, Organic and Amino Acids Quantified in a Single Procedure
Published on: June 25, 2010
Creatine transporter deficiency: prevalence among patients with mental retardation and pitfalls in metabolite
Angela Arias1, Marc Corbella, Carmen Fons
1Institut de Bioquímica Clínica, Servicio de Bioquímica y Genética Molecular, Hospital Clínic and Centre for Biomedical Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Barcelona, Spain.
Objectives:
To report the prevalence of creatine transporter deficiency in males with mental retardation and to study whether a protein-rich food intake might be a potential diagnostic pitfall.
Design And Methods:
We determined creatine/creatinine ratio in urine samples from 1600 unrelated male patients with mental retardation and/or autism. Urine creatine was analyzed by HPLC-MS/MS.
Results:
Thirty-three of 1600 cases showed increased urine creatine/creatinine ratio. Four out of these thirty-three cases were definitively diagnosed with creatine transporter deficiency, while the other 29 were false positive results. Significantly higher values were observed for urine Cr/Crn ratio in healthy volunteers after a meal based on beef or oily fish as compared to eggs, pasta or salad (Wilcoxon test: p<0.005).
Conclusions:
False positive results may be observed in biochemical screening for creatine transporter deficiency, and they may be due to intake of meals rich in creatine prior to urine samples analysis.
Related Concept Videos
Inborn Errors of Metabolism
Pharmacokinetics in Pediatric Patients: Drug Metabolism
Drug Dosing in Renal Diseases: Measurement of Serum Creatinine Concentration and Clearance
Overview of Protein Metabolism
Amino acids play various roles in the body once they are absorbed into cells. They are restructured...
Pharmacokinetics in Geriatric Patients: Effect of Age on Drug Excretion
Factors Affecting Renal Clearance: Renal Impairment
One condition associated with renal failure is uremia. Uremia is characterized by impaired glomerular filtration and fluid accumulation in the body. This condition hinders the renal clearance of drugs, resulting in drug accumulation and potential...

