Test Id : CRDPU
Creatine Disorders Panel, Random, Urine
Useful For
Suggests clinical disorders or settings where the test may be helpful
Evaluating patients with a clinical suspicion of arginine:glycine amidinotransferase deficiency, guanidinoacetate methyltransferase deficiency, and creatine transporter deficiency
Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request
Depletion of cerebral creatine occurs in all 3 types of creatine deficiency syndromes (CDS): arginine:glycine amidinotransferase deficiency, guanidinoacetate methyltransferase deficiency, and creatine transporter deficiency.
Measurement of guanidinoacetate, creatine (Cr), and creatinine (Crn) in urine, along with the Cr:Crn ratio, aids in distinguishing the types of creatine deficiency syndromes.
Treatment with oral creatine supplementation is effective in some types of CDS.
Creatine supplementation may impact reliability of test results.
Additional Tests
Lists tests that are always performed, at an additional charge, with the initial tests.
| Test Id | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| CRBO | Creatine, (Bill Only), U | No | Yes |
| CRNBO | Creatinine, (Bill Only), U | No | Yes |
| GAABO | Guanidinoacetate, (Bill Only), U | No | Yes |
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
This is a single test that carries the results for the panel. When the test has been resulted, the following procedures are billed:
-CRBO / Creatine, Urine (Bill Only)
-CRNBO / Creatinine, Urine (Bill Only)
-GAABO / Guanidinoacetate, Urine (Bill Only)
For more information see:
-Newborn Screen Follow-up for Guanidinoacetate Methyltransferase Deficiency (GAMT)
-Epilepsy: Unexplained Refractory and/or Familial Testing Algorithm
If the patient has abnormal newborn screening results for guanidinoacetate methyltransferase deficiency, refer to the appropriate ACMG Newborn Screening ACT Sheet.(1)
Method Name
A short description of the method used to perform the test
Liquid Chromatography Tandem Mass Spectometry (LC-MS/MS)
NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test
Aliases
Lists additional common names for a test, as an aid in searching
AGAT (Arginine:Glycine Amidinotransferase) Deficiency
Arginine:Glycine Amidinotransferase Deficiency (AGAT)
CrT1 defect
GAMT (Guanidinoacetate Methyltransferase) Deficiency
Guanidinoacetate Methyltransferase (GAMT) Deficiency
Guanidinoacetate
Guanidinoacetic acid
Creatine urine
Creatinine urine
Creatine/creatinine ratio urine
Creatine disorders
XLCTD
Creatine transporter deficiency
XL creatine transporter deficiency
SLC6A8 deficiency
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
This is a single test that carries the results for the panel. When the test has been resulted, the following procedures are billed:
-CRBO / Creatine, Urine (Bill Only)
-CRNBO / Creatinine, Urine (Bill Only)
-GAABO / Guanidinoacetate, Urine (Bill Only)
For more information see:
-Newborn Screen Follow-up for Guanidinoacetate Methyltransferase Deficiency (GAMT)
-Epilepsy: Unexplained Refractory and/or Familial Testing Algorithm
If the patient has abnormal newborn screening results for guanidinoacetate methyltransferase deficiency, refer to the appropriate ACMG Newborn Screening ACT Sheet.(1)
Specimen Type
Describes the specimen type validated for testing
Urine
Necessary Information
Patient's age and sex are required.
Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing
Supplies: Urine Tubes, 10 mL (T068)
Container/Tube: Plastic, 10 mL urine tube
Specimen Volume: 1 mL
Collection Instructions:
1. Collect a random urine specimen.
2. Immediately freeze urine specimen.
3. If possible, do not send other tests ordered on same vial of urine. In doing so, the other tests may have increased turnaround time due to the strict frozen criteria of this assay.
Special Instructions
Library of PDFs including pertinent information and forms related to the test
Forms
If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.
Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.
0.5 mL
Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected
Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Urine | Frozen | 29 days |
Useful For
Suggests clinical disorders or settings where the test may be helpful
Evaluating patients with a clinical suspicion of arginine:glycine amidinotransferase deficiency, guanidinoacetate methyltransferase deficiency, and creatine transporter deficiency
Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request
Depletion of cerebral creatine occurs in all 3 types of creatine deficiency syndromes (CDS): arginine:glycine amidinotransferase deficiency, guanidinoacetate methyltransferase deficiency, and creatine transporter deficiency.
Measurement of guanidinoacetate, creatine (Cr), and creatinine (Crn) in urine, along with the Cr:Crn ratio, aids in distinguishing the types of creatine deficiency syndromes.
Treatment with oral creatine supplementation is effective in some types of CDS.
Creatine supplementation may impact reliability of test results.
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
This is a single test that carries the results for the panel. When the test has been resulted, the following procedures are billed:
-CRBO / Creatine, Urine (Bill Only)
-CRNBO / Creatinine, Urine (Bill Only)
-GAABO / Guanidinoacetate, Urine (Bill Only)
For more information see:
-Newborn Screen Follow-up for Guanidinoacetate Methyltransferase Deficiency (GAMT)
-Epilepsy: Unexplained Refractory and/or Familial Testing Algorithm
If the patient has abnormal newborn screening results for guanidinoacetate methyltransferase deficiency, refer to the appropriate ACMG Newborn Screening ACT Sheet.(1)
Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Disorders of creatine synthesis (guanidinoacetate methyltransferase [GAMT] deficiency, L-arginine:glycine amidinotransferases [AGAT] deficiency, and creatine transporter deficiency [CTD]) are collectively described as creatine deficiency syndromes (CDS). AGAT and GAMT deficiencies are inherited in an autosomal recessive manner, while the creatine transporter defect is X-linked. All 3 disorders result in a depletion of cerebral creatine and typically present with global developmental delays especially expressive speech and language delay and intellectual disability. Affected patients may have abnormal magnetic resonance imaging findings and exhibit cerebral creatine deficiency in brain magnetic resonance spectroscopy. Patients with GAMT and male patients with CTD may develop seizures, autistic-like behaviors, and abnormal movements. Female carriers for CTD can be asymptomatic or exhibit features similar to affected male patients, such as intellectual disability, behavioral problems, and seizures.
Diagnosis is possible by measuring guanidinoacetate (GAA), creatine (Cr), and creatinine (Crn) in plasma and urine. The profiles are specific for each clinical entity. Patients with GAMT deficiency typically exhibit normal to low Cr, very elevated GAA, and low Crn. Patients with AGAT deficiency typically exhibit normal to low Cr, low GAA, and normal to low Crn. In comparison, elevated Cr, normal GAA, normal to low Crn, and an elevated Cr:Crn ratio characterize patients with creatine transporter defect. The only consistently reliable method for diagnosis of CTD in female patients is molecular analysis of the SLC6A8 gene. The diagnosis of GAMT, AGAT, and CTD can be confirmed by molecular analysis of GAMT,GATM, and SLC6A8 respectively.
Treatment with oral supplementation of creatine monohydrate is available and effective for the AGAT and GAMT deficiencies. Patients with GAMT deficiency may also be treated with supplemental ornithine and dietary arginine restriction. CTD is treated with oral creatine monohydrate and arginine and glycine supplementation.
Early treatment has been reported to prevent disease manifestations in affected but presymptomatic newborn siblings of individuals with GAMT or AGAT 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.
Males
| Age | Creatinine (nmol/mL) | Guanidinoacetate (nmol/mL) | Creatine (nmol/mL) | Creatine/ |
| < or =31 days | 430-5,240 | 9-210 | 12-2,930 | 0.02-0.93 |
| 32 days-23 months | 313-9,040 | 16-860 | 18-10,490 | 0.02-2.49 |
| 2-4 years | 1,140-12,820 | 90-1,260 | 200-9,210 | 0.04-1.75 |
| 5-18 years | 1,190-25,270 | 40-1,190 | 60-9,530 | 0.01-0.96 |
| >18 years (male) | 3,854-23,340 | 30-710 | 7-470 | 0.00-0.04 |
Females
| Age | Creatinine (nmol/mL) | Guanidinoacetate (nmol/mL) | Creatine (nmol/mL) | Creatine/ |
| < or =31 days | 430-5,240 | 9-210 | 12-2,930 | 0.02-0.93 |
| 32 days-23 months | 313-9,040 | 16-860 | 18-10,490 | 0.02-2.49 |
| 2-4 years | 1,140-12,820 | 90-1,260 | 200-9,210 | 0.04-1.75 |
| 5-18 years | 1,190-25,270 | 40-1,190 | 60-9,530 | 0.01-0.96 |
| >18 years | 1,540-18,050 | 30-760 | 5-2810 | 0.00-0.46 |
Interpretation
Provides information to assist in interpretation of the test results
Reports include concentrations of guanidinoacetate, creatine, and creatinine, as well as 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 are crucial to achieve reliable results.
Creatine supplementation will cause falsely elevated results.
Clinical Reference
Recommendations for in-depth reading of a clinical nature
1. ACMG Newborn Screening ACT Sheets. Accessed December 16, 2024. Available at www.acmg.net/ACMG/Medical-Genetics-Practice-Resources/ACT_Sheets_and_Algorithms/ACMG/Medical-Genetics-Practice-Resources/ACT_Sheets_and_Algorithms.aspx?hkey=9d6bce5a-182e-42a6-84a5-b2d88240c508
2. Clark JF, Cecil KM. Diagnostic methods and recommendations for the cerebral creatine deficiency syndromes. Pediatr Res. 2015;77(3):398-405
3. Mercimek-Mahmutoglu S, Salomons GS. Creatine deficiency syndromes. In: Adam MP, Mirzaa GM, Pagon RA, et al. eds. GeneReviews [Internet]. University of Washington, Seattle; 2009. Updated February 10, 2022. Accessed December 16, 2024. Available at www.ncbi.nlm.nih.gov/books/NBK3794/
4. Stockler S, Schultz PW, Salomons GS. Cerebral creatine deficiency syndromes: clinical aspects, treatment, and pathophysiology. Subcell Biochem. 2007;46:149-166
5. Longo N, Ardon O, Vanzo R, Schwartz E, Pasquali M. Disorders of creatine transport and metabolism. Am J Med Genet. 2011;157:72-78. doi:10.1002/ajmg.c.30292
6. Bahl S, Cordeiro D, MacNeil L, Schulze A, Mercimek-Andrews S. Urine creatine metabolite panel as a screening test in neurodevelopmental disorders. Orphanet J Rare Dis. 2020;15(1):339. doi:10.1186/s13023-020-01617-z
7. Fernandes-Pires G, Braissant O. Current and potential new treatment strategies for creatine deficiency syndromes. Mol Genet Metab. 2022;135(1):15-26. doi:10.1016/j.ymgme.2021.12.005
Method Description
Describes how the test is performed and provides a method-specific reference
A random urine sample is combined with stable isotope-labeled internal standards and acetonitrile. After centrifugation, an aliquot of this diluted sample is analyzed by injection onto liquid chromatography columns that separate the analytes from the bulk of the stable isotope dilution in the positive electrospray selected reaction monitoring mode using the Applied Biosystems API 3200 liquid chromatography tandem mass spectrometry system with Analyst software.(Bodamer OA, Bloesch SM, Gregg AR, Stockler-Ipsiroglue S, O'Brien WEO. Analysis of guanidinoacetate and creatine by isotope dilution electroscopy tandem mass spectrometry. Clin Chim Acta. 2001;308:173-178; Cognat S, Cheillan D, Piraud M, Roos B, Jakobs C, Vianey-Saban C. Determination of guanidinoacetate and creatine in urine and plasma by liquid chromatography-tandem mass spectrometry. Clin Chem. 2004;50[8]:1459-1461)
PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information
Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.
Tuesday
Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.
Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location
Indicates the location of the laboratory that performs the test
Fees :
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.
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- Prospective clients should contact their account representative. For assistance, contact Customer Service.
Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.
CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
CPT codes are provided by the performing laboratory.
CPT codes are provided by the performing laboratory.
82540
82570
82542
LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.
| Test Id | Test Order Name | Order LOINC Value |
|---|---|---|
| CRDPU | Creatine Disorders Panel, U | 79290-3 |
| Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
|---|---|---|
| 23383 | Creatine | 15046-6 |
| 23384 | Creatinine | 14683-7 |
| 23385 | Guanidinoacetate | 97148-1 |
| 23268 | Creatine/Creatinine Ratio | 34275-8 |
| 23270 | Creatine Disorders Panel Interp | 79292-9 |
| 23272 | Reviewed By | 18771-6 |