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Test ID CRDPU Creatine Disorders Panel, Random, Urine

Reporting Name

Creatine Disorders Panel, U

Useful For

Evaluation of patients with a clinical suspicion of inborn errors of creatine metabolism including arginine:glycine amidinotransferase deficiency, guanidinoacetate methyltransferase deficiency, and creatine transporter (SLC6A8) defect

Additional 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

CRDPU / Creatine Disorders Panel, Urine is a single test that carries the results for the panel. When the test is 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 Screening Act Sheet Guanidinoacetate Methyltransferase Deficiency: Increased Guanidinoacetate in Special Instructions.

 

The following algorithms are available in Special Instructions:

-Newborn Screen Follow-up for Guanidinoacetate Methyltransferase Deficiency (GAMT)

-Epilepsy: Unexplained Refractory and/or Familial Testing Algorithm

Specimen Type

Urine


Specimen Required


Supplies: Urine Tubes, 10 mL (T068)

Specimen Volume: 1 mL

Collection Instructions:

1. Collect a random urine specimen.

2. Immediately freeze 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.


Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Urine Frozen 29 days

Reference Values

Males

Age

Creatinine (nmol/mL)

Guanidinoacetate (nmol/mL)

Creatine (nmol/mL)

Creatine/
Creatinine

≤31 days

430-5,240

9-210

12-2930

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/
Creatinine

≤31 days

430-5,240

9-210

12-2930

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

Day(s) and Time(s) Performed

Tuesday; 12 p.m.

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

82540-Creatine

82570-Creatinine

82542-Guanidinoacetate

LOINC Code Information

Test ID Test Order Name Order LOINC Value
CRDPU Creatine Disorders Panel, U 79290-3

 

Result ID Test Result Name Result LOINC Value
23383 Creatine 15046-6
23384 Creatinine 14683-7
23385 Guanidinoacetate 33244-5
23268 Creatine/Creatinine Ratio 34275-8
23270 Creatine Disorders Panel Interp 79292-9
23272 Reviewed By 18771-6

Clinical Information

Disorders of creatine synthesis (deficiency of arginine:glycine amidinotransferases: AGAT and guanidinoacetate methyltransferase: GAMT) and creatine transporter (SLC6A8) deficiency 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, intellectual disability, and severe speech delay. Commonly, patients with CDS develop seizures. Patients with GAMT and the creatine transporter deficiency exhibit behavioral problems and features of autism. Female carriers for the creatine transporter deficiency can have intellectual disability and behavioral problems, and some develop 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.

 

Treatment with oral supplementation of creatine monohydrate is available and effective for the AGAT and GAMT deficiencies. Early treatment has been reported to prevent disease manifestations in affected but presymptomatic newborn siblings of individuals with GAMT or AGAT deficiencies. Creatine supplementation has not been shown to improve outcomes in males with the creatine transporter defect. Female carriers of creatine transporter deficiency who have symptoms, however, have been reported to benefit from creatine supplementation.

Interpretation

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.

Clinical Reference

1. Clark JF, Cecil KM: Diagnostic methods and recommendations for the cerebral creatine deficiency syndromes. Pediatr Res 2015 Mar;77(3):398-405

2. Mercimek-Mahmutoglu S, Salomons GS: Creatine deficiency syndromes. In GeneReviews. Edited by RA Pagon, MP Adam, HH Ardinger, et al. Jan 15 2009 University of Washington, Seattle; Updated 2015 Dec 10. Accessed 2/7/2018. Available at www.ncbi.nlm.nih.gov/books/NBK3794/

3. Stockler S, Schultz PW, Salomons GS: Cerebral creatine deficiency syndromes: clinical aspects, treatment and pathophysiology. Subcell Biochem 2007;46:149-166

4. Longo N, Ardon O, Vanzo R, et al: Disorders of creatine transport and metabolism. Am J Med Genet 2011;157:72-78 doi: 10.1002/ajmg.c.30292

Analytic Time

7 days

Method Name

Liquid Chromatography-Tandem Mass Spectometry (LC-MS/MS)

Forms

If not ordering electronically, complete, print, and send an Inborn Errors of Metabolism Test Request (T798) with the specimen. 

Mayo Clinic Laboratories | Pediatric Catalog Additional Information:

mcl-newborn