Test ID: CRDPU
Creatine Disorders Panel, Urine
Useful For 
Suggests clinical disorders or settings where the test may be helpful
Evaluation of patients with a clinical suspicion of inborn errors of creatine metabolism including arginine:glycine amidinotransferase deficiency, guanidinoacetate methyltransferase deficiency, and creatine transporter (CrT1) defect
Genetics Test Information Provides information that may help with selection of the correct test or proper submission of the test request
Evaluation of patients with a clinical suspicion of inborn errors of creatine metabolism including argine:glycine amidinotransferase deficiency (AGAT), guanidinoacetate methyltransferase deficiency (GAMT), and CrT1 defect. Correct specimen collection and handling is crucial to achieve reliable results. Creatine supplementation will cause falsely elevated results.
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Disorders of creatine synthesis (eg, deficiency of arginine:glycine amidinotransferase [AGAT] and guanidinoacetate methyltransferase [GAMT]) and defects of the creatine transporter (CrT1), also called SLC6A8, are collectively described as creatine deficiency syndromes (CDS). AGAT and GAMT deficiencies are inherited in an autosomal recessive manner, while the CrT1 defect is X-linked. Defects in any of these enzymes disrupt energy metabolism of the cells and typically present with a common set of symptoms which include mental retardation, speech and language delay, behavioral changes, and epilepsy.
Diagnosis is possible by measuring guanidinoacetate, creatine, and creatinine in plasma and urine. Different profiles are specific for each clinical entity. In particular, the creatine/creatinine ratio is a useful marker of the CrT1 defect.
Treatment with oral supplementation of creatine monohydrate is available and effective, especially in AGAT and GAMT deficiencies.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
CREATININE
Males
1-31 days: 430-5,240 nmol/mL
32 days-23 months: 313-9,040 nmol/mL
2-4 years: 1,140-12,820 nmol/mL
5-18 years: 1,190-25,270 nmol/mL
>18 years: 1,540-23,340 nmol/mL
Females
1-31 days: 430-5,240 nmol/mL
32 days-23 months: 313-9,040 nmol/mL
2-4 years: 1,140-12,820 nmol/mL
5-18 years: 1,190-25,270 nmol/mL
>18 years: 1,540-18,050 nmol/mL
GUANIDINOACETATE
Males
1-31 days: 9-210 nmol/mL
32 days-23 months: 16-860 nmol/mL
2-4 years: 90-1,260 nmol/mL
5-18 years: 40-1,190 nmol/mL
>18 years: 30-710 nmol/mL
Females
1-31 days: 9-210 nmol/mL
32 days-23 months: 16-860 nmol/mL
2-4 years: 90-1,260 nmol/mL
5-18 years: 40-1,190 nmol/mL
>18 years: 30-760 nmol/mL
CREATINE
Males
1-31 days: 12-2,930 nmol/mL
32 days-23 months: 18-10,490 nmol/mL
2-4 years: 200-9,210 nmol/mL
5-18 years: 60-9,530 nmol/mL
>18 years: 7-470 nmol/mL
Females
1-31 days: 12-2,930 nmol/mL
32 days-23 months: 18-10,490 nmol/mL
2-4 years: 200-9,210 nmol/mL
5-18 years: 60-9,530 nmol/mL
>18 years: 5-2,810 nmol/mL
CREATINE/CREATININE
Males
1-31 days: 0.02-0.93
32 days-23 months: 0.02-2.49
2-4 years: 0.04-1.75
5-18 years: 0.01-0.96
>18 years: 0.00-0.04
Females
1-31 days: 0.02-0.93
32 days-23 months: 0.02-2.49
2-4 years: 0.04-1.75
5-18 years: 0.01-0.96
>18 years: 0.00-0.46
Interpretation Provides information to assist in interpretation of the test results
Reports include concentrations of guanidinoacetate, creatine, and creatinine, and a calculated creatine/creatinine ratio. When no significant abnormalities are detected, a simple descriptive interpretation is provided. When abnormal results are detected, a detailed interpretation is given. This interpretation includes an overview of the results and their significance, a correlation to available clinical information, elements of differential diagnosis, and recommendations for additional biochemical testing.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Correct specimen collection and handling is crucial to achieve reliable results.
Creatine supplementation will cause falsely-elevated results.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Sykut-Cegielska J, Gradowska W, Mercimek-Mahutoglu S, Stockler-Ipsiroglu S: Biochemical and clinical characteristics of creatine deficiency syndromes. Acta Biochim Pol 2004;51:875-882
2. Stromberger C, Bodamer OA, Stocler-Ipsiroglu S: Clinical characteristics and diagnostic clues in inborn errors of creatine metabolism. J Inherit Metab Dis 2003;26:299-308
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