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Order Code CRDPU Creatine Disorders Panel, Random, Urine

Reporting Name

Creatine Disorders Panel, U

Useful For

Evaluating patients with a clinical suspicion of 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

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

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Urine


Necessary Information


Patient's age and sex are required.



Specimen Required


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.


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

12-2,930

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/

creatinine

≤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

Day(s) Performed

Tuesday

CPT Code Information

82540

82570

82542

Method Description

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)

Reject Due To

  All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Method Name

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

Genetics Test Information

Depletion of cerebral creatine occurs in all 3 types of creatine deficiency syndromes (CDS): arginine:glycine amidinotransferase deficiency, guanidinoacetate methyltransferase deficiency, and creatine transporter (SLC6A8) 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 cause increased creatine values.