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Email:	mcl@mayo.edu
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Test Id : CRDPP

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Creatine Disorders Panel, Plasma

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Overview

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 using plasma specimens

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, and creatinine, along with associated analyte ratios in plasma and urine, 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.

For more information see:

-Newborn Screen Follow-up for Guanidinoacetate Methyltransferase Deficiency

-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 Spectrometry (LC-MS/MS)

NY State Available

Indicates the status of NY State approval and if the test is orderable for NY State clients.

Yes

Reporting Name

Lists a shorter or abbreviated version of the Published Name for a test

Creatine Disorders Panel, P

Aliases

Lists additional common names for a test, as an aid in searching

AGAT (Arginine:Glycine Amidinotransferase) Deficiency

Arginine:Glycine Amidinotransferase Deficiency (AGAT)

Creatine disorders

Creatine plasma

Creatine/creatinine ratio plasma

Creatinine plasma

GAMT (Guanidinoacetate Methyltransferase) Deficiency

Guanidinoacetate

Guanidinoacetate Methyltransferase (GAMT) Deficiency

Guanidinoacetic acid (GAA)

L-Arginine:Glycine Amidinotransferase Deficiency (AGAT)

Creatine transporter deficiency

SLC6A8 creatine transporter deficiency

XLCTD (X-linked Creatine Transporter Deficiency)

Testing Algorithm

Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

For more information see:

-Newborn Screen Follow-up for Guanidinoacetate Methyltransferase Deficiency

-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

Plasma

Ordering Guidance

For additional diagnostic testing, consider ordering CRDPU / Creatine Disorders Panel, Random, Urine.

Additional Testing Requirements

To diagnose all creatine deficiency syndromes, order CRDPU / Creatine Disorders Panel, Random, Urine in addition to this test.

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

Collection Container/Tube:

Preferred: Lavender top (EDTA)

Acceptable: Green top (sodium heparin), yellow top (ACD)

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL

Collection Instructions: Centrifuge and aliquot plasma into plastic vial. Send plasma frozen.

Special Instructions

Library of PDFs including pertinent information and forms related to the test

Forms

1. Biochemical Genetics Patient Information (T602)

2. 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.

0.1 mL

Reject Due To

Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis	OK
Gross lipemia	OK
Gross icterus	OK

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
Plasma	Frozen (preferred)	14 days
	Refrigerated	7 days
	Ambient	72 hours

Useful For

Suggests clinical disorders or settings where the test may be helpful

Genetics Test Information

Provides information that may help with selection of the correct genetic test or proper submission of the test request

Measurement of guanidinoacetate, creatine, and creatinine, along with associated analyte ratios in plasma and urine, 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.

For more information see:

-Newborn Screen Follow-up for Guanidinoacetate Methyltransferase Deficiency

-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). GAMT and AGAT deficiencies are inherited in an autosomal recessive manner, while CTD 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. 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 develop seizures, behavioral problems, and autistic features and may have 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 of creatine synthesis disorders relies on measurement of guanidinoacetate (GAA), creatine (Cr), and creatinine (Crn) in plasma and urine. The profiles are specific for each clinical entity. In plasma, patients with GAMT deficiency typically exhibit very elevated GAA, low Cr, and normal to low Crn. Patients with AGAT deficiency typically exhibit low to normal GAA, low Cr, and normal to low Crn. Patients with CTD may have normal or abnormal plasma levels of GAA, Cr and Crn, and measurement of these analytes in urine is also useful for diagnosis in male patients (characteristic findings are elevated Cr, normal to low Crn, and an elevated Cr:Crn ratio in urine). The only consistently reliable method for diagnosis of CTD in female patients is molecular analysis of the SLC6A8 gene. The diagnosis of GAMT and AGAT and CTD can be confirmed by molecular analysis of GAMT and GATM and SLC6A8.

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.

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.

Creatine Disorders Panel Reference Values
(creatine, creatinine, and guanidinoacetate results reported as nmol/mL)

< or =11 Months

12-23 Months

24-35 Months

Female

Male

Female

Male

Female

Male

Creatine

38.6-96.8

39.0-97.0

38.2-96.5

38.6-96.5

37.7-96.0

38.2-96.0

Creatinine

27.6-35.9

27.6-35.2

27.6-36.5

27.6-35.5

27.6-37.1

27.6-36.0

Guanidinoacetate

0.7-2.0

0.7-2.1

0.7-2.0

0.7-2.1

0.7-2.0

0.7-2.1

Creatine/
creatinine

< or =3.07

< or =3.60

< or =3.02

< or =3.54

< or =2.96

< or =3.48

Guanidinoacetate/
creatine

< or =0.040

< or =0.042

< or =0.040

< or =0.043

< or =0.042

Guanidinoacetate/
creatinine

< or =0.051

< or =0.081

< or =0.051

< or =0.080

< or =0.051

< or =0.079

3 Years

4 Years

5 Years

Female

Male

Female

Male

Female

Male

Creatine

37.1-95.5

37.7-95.3

36.0-94.4

36.8-94.1

34.6-93.2

35.6-92.7

Creatinine

27.6-37.9

27.7-36.9

27.6-39.3

27.7-38.2

27.6-40.9

27.8-39.9

Guanidinoacetate

0.7-2.1

0.7-2.2

0.7-2.1

0.7-2.2

0.7-2.1

0.7-2.2

Creatine/
creatinine

< or =2.89

< or =3.40

< or =2.77

< or =3.26

< or =2.64

< or =3.09

Guanidinoacetate/
creatine

< or =0.045

< or =0.043

< or =0.049

< or =0.045

< or =0.053

< or =0.049

Guanidinoacetate/
creatinine

< or =0.050

< or =0.077

< or =0.050

< or =0.075

< or =0.049

< or =0.072

	6 Years		7 Years		8 Years
	Female	Male	Female	Male	Female	Male
Creatine	33.0-91.7	34.3-91.0	31.2-90.0	32.7-89.2	29.2-88.1	31.0-87.3
Creatinine	27.6-42.8	28.0-41.9	27.7-44.9	28.3-44.3	27.8-47.0	28.8-47.1
Guanidinoacetate	0.7-2.1	0.7-2.3	0.7-2.1	0.8-2.3	0.8-2.1	0.8-2.4
Creatine/ creatinine	< or =2.49	< or =2.91	< or =2.33	< or =2.70	< or =2.17	< or =2.49
Guanidinoacetate/ creatine	< or =0.058	< or =0.053	< or =0.063	< or =0.058	< or =0.069	< or =0.064
Guanidinoacetate/ creatinine	< or =0.049	< or =0.069	< or =0.048	< or =0.066	< or =0.047	< or =0.063

	9 Years		10 Years		11 Years
	Female	Male	Female	Male	Female	Male
Creatine	27.2-85.9	29.3-85.2	25.2-83.7	27.4-83.1	23.4-81.3	25.7-80.9
Creatinine	28.0-49.3	29.5-50.1	28.2-51.5	30.6-53.6	28.4-53.6	32.0-57.2
Guanidinoacetate	0.8-2.2	0.8-2.5	0.9-2.2	0.9-2.6	0.9-2.2	1.0-2.6
Creatine/ creatinine	< or =2.02	< or =2.28	< or =1.86	< or =2.07	< or =1.72	< or =1.87
Guanidinoacetate/ creatine	< or =0.075	< or =0.070	< or =0.081	< or =0.078	< or =0.087	< or =0.085
Guanidinoacetate/ creatinine	< or =0.047	< or =0.060	< or =0.046	< or =0.057	< or =0.045	< or =0.055

	12 Years		13 Years		14 Years
	Female	Male	Female	Male	Female	Male
Creatine	21.7-78.7	23.9-78.6	20.3-76.2	22.3-76.2	19.0-73.6	20.8-73.8
Creatinine	28.7-55.7	33.8-61.0	29.1-57.7	35.9-64.8	29.5-59.5	38.1-68.5
Guanidinoacetate	0.9-2.2	1.0-2.7	1.0-2.3	1.1-2.8	1.0-2.3	1.1-2.9
Creatine/ creatinine	< or =1.58	< or =1.68	< or =1.45	< or =1.50	< or =1.33	< or =1.34
Guanidinoacetate/ creatine	< or =0.092	< or =0.093	< or =0.097	< or =0.101	< or =0.101	< or =0.109
Guanidinoacetate/ creatinine	< or =0.044	< or =0.053	< or =0.043	< or =0.051	< or =0.042	< or =0.050

	15 Years		16 Years		17 Years
	Female	Male	Female	Male	Female	Male
Creatine	18.1-71.1	19.5-71.2	17.4-68.7	18.4-68.6	16.9-66.5	17.4-65.9
Creatinine	29.9-61.3	40.4-71.9	30.4-62.9	42.4-75.0	30.9-64.4	44.2-77.6
Guanidinoacetate	1.0-2.3	1.2-2.9	1.1-2.3	1.3-3.0	1.1-2.3	1.3-3.1
Creatine/ creatinine	< or =1.22	< or =1.20	< or =1.12	< or =1.07	< or =1.04	< or =0.97
Guanidinoacetate/ creatine	< or =0.104	< or =0.117	< or =0.107	< or =0.125	< or =0.109	< or =0.132
Guanidinoacetate/ creatinine	< or =0.041	< or =0.049	< or =0.040	< or =0.048	< or =0.040	< or =0.048

	18 Years		19 Years		20 Years
	Female	Male	Female	Male	Female	Male
Creatine	16.7-64.4	16.6-63.3	16.6-62.7	15.8-60.7	16.5-61.1	15.2-58.3
Creatinine	31.3-65.8	45.6-80.0	31.8-67.0	46.7-82.0	32.2-68.2	47.4-83.9
Guanidinoacetate	1.1-2.4	1.4-3.1	1.1-2.4	1.4-3.2	1.1-2.4	1.5-3.2
Creatine/ creatinine	< or =0.98	< or =0.87	< or =0.93	< or =0.80	< or =0.89	< or =0.73
Guanidinoacetate/ creatine	< or =0.111	< or =0.139	< or =0.112	< or =0.145	< or =0.113	< or =0.150
Guanidinoacetate/ creatinine	< or =0.039	< or =0.047	< or =0.038	< or =0.047	< or =0.038	< or =0.046

	21 Years		22 Years		23 Years
	Female	Male	Female	Male	Female	Male
Creatine	16.6-59.8	14.7-56.0	16.6-58.8	14.2-54.0	16.7-57.9	13.7-52.2
Creatinine	32.5-69.2	47.9-85.6	32.8-70.2	48.2-87.2	33.1-71.1	48.4-88.8
Guanidinoacetate	1.1-2.4	1.5-3.2	1.1-2.5	1.5-3.3	1.1-2.5	1.6-3.3
Creatine/ creatinine	< or =0.87	< or =0.68	< or =0.85	< or =0.64	< or =0.84	< or =0.61
Guanidinoacetate/ creatine	< or =0.114	< or =0.156	< or =0.115	< or =0.161	< or =0.116	< or =0.165
Guanidinoacetate/ creatinine	< or =0.037	< or =0.045	< or =0.037	< or =0.045	< or =0.037	< or =0.044

	24 Years		25 Years		26 Years
	Female	Male	Female	Male	Female	Male
Creatine	16.7-57.2	13.3-50.6	16.7-56.5	12.9-49.3	16.7-56.0	12.5-48.1
Creatinine	33.3-71.9	48.6-90.2	33.6-72.8	48.7-91.5	33.7-73.6	48.9-92.7
Guanidinoacetate	1.1-2.5	1.6-3.3	1.1-2.5	1.6-3.3	1.1-2.6	1.6-3.4
Creatine/ creatinine	< or =0.84	< or =0.58	< or =0.84	< or =0.56	< or =0.84	< or =0.54
Guanidinoacetate/ creatine	< or =0.116	< or =0.170	< or =0.117	< or =0.174	< or =0.118	< or =0.179
Guanidinoacetate/ creatinine	< or =0.036	< or =0.043	< or =0.036	< or =0.043	< or =0.036	< or =0.042

	27 Years		28 Years		29 Years
	Female	Male	Female	Male	Female	Male
Creatine	16.7-55.5	12.1-47.1	16.6-55.1	11.8-46.3	16.5-54.7	11.5-45.4
Creatinine	33.9-74.4	49.0-93.7	34.1-75.2	49.1-94.5	34.2-76.0	49.2-95.3
Guanidinoacetate	1.1-2.6	1.6-3.4	1.1-2.6	1.6-3.4	1.1-2.6	1.6-3.4
Creatine/ creatinine	< or =0.84	< or =0.52	< or =0.84	< or =0.51	< or =0.84	< or =0.49
Guanidinoacetate/ creatine	< or =0.118	< or =0.182	< or =0.119	< or =0.186	< or =0.119	< or =0.188
Guanidinoacetate/ creatinine	< or =0.036	< or =0.042	< or =0.036	< or =0.041	< or =0.036	< or =0.041

	30 Years		31 Years		32 Years
	Female	Male	Female	Male	Female	Male
Creatine	16.4-54.2	11.3-44.7	16.4-53.8	11.1-43.9	16.3-53.4	11.0-43.2
Creatinine	34.4-76.8	49.3-96.0	34.6-77.5	49.3-96.7	34.7-78.2	49.4-97.4
Guanidinoacetate	1.2-2.7	1.6-3.5	1.2-2.7	1.6-3.5	1.2-2.7	1.6-3.5
Creatine/ creatinine	< or =0.84	< or =0.48	< or =0.83	< or =0.47	< or =0.83	< or =0.46
Guanidinoacetate/ creatine	< or =0.120	< or =0.190	< or =0.120	< or =0.192	< or =0.119	< or =0.192
Guanidinoacetate/ creatinine	< or =0.036	< or =0.041	< or =0.036	< or =0.042	< or =0.037	< or =0.042

	33 Years		34 Years		35 Years
	Female	Male	Female	Male	Female	Male
Creatine	16.3-53.0	10.9-42.5	16.4-52.7	10.8-41.7	16.4-52.3	10.7-41.0
Creatinine	34.9-78.8	49.4-98.0	35.1-79.4	49.5-98.6	35.3-79.9	49.5-99.2
Guanidinoacetate	1.2-2.8	1.6-3.5	1.2-2.8	1.6-3.5	1.2-2.8	1.6-3.4
Creatine/ creatinine	< or =0.82	< or =0.45	< or =0.82	< or =0.45	< or =0.82	< or =0.44
Guanidinoacetate/ creatine	< or =0.119	< or =0.192	< or =0.118	< or =0.191	< or =0.118	< or =0.189
Guanidinoacetate/ creatinine	< or =0.037	< or =0.042	< or =0.037	< or =0.042	< or =0.037	< or =0.042

	36 Years		37 Years		38 Years
	Female	Male	Female	Male	Female	Male
Creatine	16.5-52.0	10.7-40.2	16.7-51.6	10.6-39.5	16.9-51.3	10.6-38.9
Creatinine	35.4-80.3	49.5-99.8	35.6-80.7	49.5-100.3	35.8-81.0	49.6-100.8
Guanidinoacetate	1.2-2.8	1.6-3.4	1.2-2.8	1.6-3.4	1.2-2.9	1.6-3.4
Creatine/ creatinine	< or =0.82	< or =0.44	< or =0.82	< or =0.44	< or =0.83	< or =0.44
Guanidinoacetate/ creatine	< or =0.117	< or =0.187	< or =0.115	< or =0.184	< or =0.114	< or =0.182
Guanidinoacetate/ creatinine	< or =0.037	< or =0.042	< or =0.037	< or =0.042	< or =0.036	< or =0.042

	39 Years		40 Years		41 Years
	Female	Male	Female	Male	Female	Male
Creatine	17.1-51.1	10.6-38.2	17.3-50.9	10.7-37.7	17.5-50.8	10.7-37.2
Creatinine	35.9-81.4	49.6-101.3	36.0-81.6	49.6-101.7	36.1-81.9	49.7-102.1
Guanidinoacetate	1.2-2.9	1.6-3.4	1.2-2.9	1.6-3.4	1.2-2.9	1.6-3.4
Creatine/ creatinine	< or =0.83	< or =0.44	< or =0.83	< or =0.44	< or =0.84	< or =0.44
Guanidinoacetate/ creatine	< or =0.113	< or =0.179	< or =0.111	< or =0.176	< or =0.110	< or =0.174
Guanidinoacetate/ creatinine	< or =0.036	< or =0.041	< or =0.036	< or =0.041	< or =0.036	< or =0.040

	42 Years		43 Years		44 Years
	Female	Male	Female	Male	Female	Male
Creatine	17.7-50.8	10.8-36.7	17.8-50.8	10.9-36.3	17.8-50.9	11.0-36.0
Creatinine	36.2-82.1	49.7-102.5	36.3-82.4	49.8-102.8	36.4-82.6	49.8-103.1
Guanidinoacetate	1.2-3.0	1.6-3.3	1.2-3.0	1.6-3.3	1.2-3.0	1.6-3.3
Creatine/ creatinine	< or =0.84	< or =0.44	< or =0.84	< or =0.43	< or =0.84	< or =0.43
Guanidinoacetate/ creatine	< or =0.109	< or =0.172	< or =0.108	< or =0.171	< or =0.107	< or =0.170
Guanidinoacetate/ creatinine	< or =0.036	< or =0.039	< or =0.036	< or =0.039	< or =0.036	< or =0.038

	45 Years		46 Years		47 Years
	Female	Male	Female	Male	Female	Male
Creatine	17.7-51.0	11.1-35.6	17.6-51.2	11.2-35.3	17.4-51.4	11.3-35.1
Creatinine	36.4-82.8	49.9-103.4	36.5-83.0	49.9-103.6	36.5-83.2	49.9-103.9
Guanidinoacetate	1.2-3.0	1.7-3.3	1.2-3.1	1.7-3.3	1.2-3.1	1.7-3.3
Creatine/ creatinine	< or =0.84	< or =0.42	< or =0.83	< or =0.41	< or =0.83	< or =0.40
Guanidinoacetate/ creatine	< or =0.106	< or =0.169	< or =0.106	< or =0.168	< or =0.106	< or =0.167
Guanidinoacetate/ creatinine	< or =0.037	< or =0.038	< or =0.037	< or =0.037	< or =0.037	< or =0.037

	48 Years		49 Years		50 Years
	Female	Male	Female	Male	Female	Male
Creatine	17.2-51.7	11.5-34.8	17.1-51.9	11.6-34.6	17.0-52.1	11.7-34.4
Creatinine	36.6-83.4	49.9-104.1	36.6-83.5	49.9-104.2	36.7-83.7	49.9-104.4
Guanidinoacetate	1.2-3.1	1.7-3.3	1.2-3.1	1.7-3.3	1.2-3.1	1.7-3.3
Creatine/ creatinine	< or =0.82	< or =0.39	< or =0.82	< or =0.38	< or =0.82	< or =0.38
Guanidinoacetate/ creatine	< or =0.106	< or =0.166	< or =0.106	< or =0.164	< or =0.105	< or =0.163
Guanidinoacetate/ creatinine	< or =0.038	< or =0.036	< or =0.038	< or =0.036	< or =0.039	< or =0.036

	51 Years		52 Years		53 Years
	Female	Male	Female	Male	Female	Male
Creatine	17.0-52.2	11.9-34.3	17.1-52.3	12.0-34.3	17.3-52.4	12.2-34.3
Creatinine	36.8-83.9	49.8-104.6	36.8-84.0	49.8-104.8	36.9-84.2	49.8-104.9
Guanidinoacetate	1.2-3.1	1.7-3.3	1.2-3.1	1.7-3.2	1.2-3.1	1.6-3.2
Creatine/ creatinine	< or =0.82	< or =0.37	< or =0.82	< or =0.37	< or =0.82	< or =0.38
Guanidinoacetate/ creatine	< or =0.105	< or =0.161	< or =0.104	< or =0.159	< or =0.103	< or =0.157
Guanidinoacetate/ creatinine	< or =0.039	< or =0.036	< or =0.039	< or =0.036	< or =0.039	< or =0.036

	54 Years		55 Years		56 Years
	Female	Male	Female	Male	Female	Male
Creatine	17.6-52.5	12.4-34.3	18.1-52.6	12.5-34.4	18.6-52.7	12.6-34.4
Creatinine	37.0-84.4	49.8-105.0	37.1-84.5	49.8-105.2	37.2-84.7	49.8-105.3
Guanidinoacetate	1.2-3.1	1.6-3.2	1.2-3.1	1.6-3.2	1.2-3.1	1.6-3.2
Creatine/ creatinine	< or =0.82	< or =0.38	< or =0.83	< or =0.39	< or =0.84	< or =0.40
Guanidinoacetate/ creatine	< or =0.102	< or =0.155	< or =0.100	< or =0.154	< or =0.099	< or =0.152
Guanidinoacetate/ creatinine	< or =0.039	< or =0.036	< or =0.039	< or =0.036	< or =0.039	< or =0.036

	57 Years		58 Years		59 Years
	Female	Male	Female	Male	Female	Male
Creatine	19.2-52.9	12.7-34.4	19.9-53.1	12.8-34.3	20.5-53.3	12.8-34.2
Creatinine	37.3-84.9	49.8-105.4	37.4-85.1	49.8-105.5	37.6-85.2	49.8-105.6
Guanidinoacetate	1.2-3.0	1.6-3.2	1.3-3.0	1.6-3.2	1.3-3.0	1.6-3.2
Creatine/ creatinine	< or =0.84	< or =0.40	< or =0.85	< or =0.41	< or =0.86	< or =0.42
Guanidinoacetate/ creatine	< or =0.098	< or =0.151	< or =0.096	< or =0.151	< or =0.095	< or =0.150
Guanidinoacetate/ creatinine	< or =0.039	< or =0.036	< or =0.038	< or =0.036	< or =0.038	< or =0.036

	60 Years		61 Years		62 Years
	Female	Male	Female	Male	Female	Male
Creatine	21.0-53.6	12.8-34.1	21.5-53.9	12.7-34.0	21.9-54.2	12.6-33.9
Creatinine	37.8-85.4	49.9-105.7	38.0-85.5	49.9-105.9	38.3-85.7	49.9-106.0
Guanidinoacetate	1.3-2.9	1.6-3.2	1.3-2.9	1.6-3.1	1.3-2.9	1.6-3.1
Creatine/ creatinine	< or =0.87	< or =0.43	< or =0.87	< or =0.44	< or =0.88	< or =0.44
Guanidinoacetate/ creatine	< or =0.094	< or =0.150	< or =0.093	< or =0.150	< or =0.093	< or =0.150
Guanidinoacetate/ creatinine	< or =0.037	< or =0.036	< or =0.036	< or =0.035	< or =0.036	< or =0.035

	63 Years		64 Years		65 Years
	Female	Male	Female	Male	Female	Male
Creatine	22.2-54.6	12.4-33.7	22.3-55.0	12.3-33.6	22.5-55.5	12.2-33.4
Creatinine	38.7-85.8	50.0-106.1	39.1-85.9	50.0-106.3	39.6-86.1	50.1-106.4
Guanidinoacetate	1.3-2.8	1.6-3.1	1.3-2.8	1.6-3.1	1.3-2.8	1.6-3.1
Creatine/ creatinine	< or =0.88	< or =0.45	< or =0.89	< or =0.46	< or =0.89	< or =0.46
Guanidinoacetate/ creatine	< or =0.092	< or =0.150	< or =0.092	< or =0.149	< or =0.091	< or =0.149
Guanidinoacetate/ creatinine	< or =0.035	< or =0.035	< or =0.034	< or =0.034	< or =0.034	< or =0.034

	66 Years		67 Years		68 Years
	Female	Male	Female	Male	Female	Male
Creatine	22.6-55.9	12.3-33.1	22.7-56.3	12.3-32.8	22.9-56.7	12.5-32.4
Creatinine	40.2-86.2	50.2-106.6	40.7-86.3	50.3-106.7	41.3-86.5	50.4-106.9
Guanidinoacetate	1.3-2.7	1.6-3.1	1.3-2.7	1.6-3.0	1.4-2.7	1.6-3.0
Creatine/ creatinine	< or =0.90	< or =0.47	< or =0.90	< or =0.48	< or =0.90	< or =0.48
Guanidinoacetate/ creatine	< or =0.091	< or =0.149	< or =0.090	< or =0.148	< or =0.090	< or =0.148
Guanidinoacetate/ creatinine	< or =0.034	< or =0.034	< or =0.033	< or =0.034	< or =0.033	< or =0.034

	69 Years		70 Years		> or = 71 Years
	Female	Male	Female	Male	Female	Male
Creatine	23.2-57.0	12.8-32.0	23.6-57.2	13.1-31.4	24.1-57.3	13.6-30.8
Creatinine	41.9-86.6	50.5-107.1	42.4-86.8	50.7-107.4	42.8-86.9	50.8-107.6
Guanidinoacetate	1.4-2.6	1.6-3.0	1.4-2.6	1.6-3.0	1.4-2.5	1.5-3.0
Creatine/ creatinine	< or =0.90	< or =0.48	< or =0.90	< or =0.48	< or =0.90	< or =0.48
Guanidinoacetate/ creatine	< or =0.090	< or =0.148	< or =0.090	< or =0.148	< or =0.090	< or =0.148
Guanidinoacetate/ creatinine	< or =0.033	< or =0.034	< or =0.033	< or =0.034	< or =0.033	< or =0.034

Interpretation

Provides information to assist in interpretation of the test results

Reports include concentrations of guanidinoacetate, creatine, and creatinine, and the calculated analyte ratios. 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

Creatine supplementation will cause falsely elevated creatine results and falsely decreased guanidinoacetate results.

Guanidinoacetate can be elevated in patients with urea cycle defects.

Clinical Reference

Recommendations for in-depth reading of a clinical nature

1. ACMG Newborn Screening ACT Sheets. Accessed October 30, 2023. 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. Sanders K, Peck D, Bentz Pino G, et al. SLC6A8 creatine transporter deficiency can be detected by plasma creatine and creatinine concentrations. Mol Genet Metab. 2024;142(1):108455. doi:10.1016/j.ymgme.2024.108455

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

4. 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 March 30, 2023. Available at www.ncbi.nlm.nih.gov/books/NBK3794/

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

6.. 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

Method Description

Describes how the test is performed and provides a method-specific reference

A plasma 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-Ipsiroglu 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; Sharer JD, Bodamer O, Longo N, Tortorelli S, Wamelink M, Young S. Laboratory diagnosis of creatine deficiency syndromes: a technical standard and guideline of the American College of Medical Genetics and Genomics. Genet Med. 2017;19[2]:256-263)

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.

3 to 9 days

Specimen Retention Time

Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

1 month

Performing Laboratory Location

Indicates the location of the laboratory that performs the test

Rochester

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.

Authorized users can sign in to Test Prices for detailed fee information.
Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
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.

82540

82565

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
CRDPP	Creatine Disorders Panel, P	104537-6

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.
608071	Interpretation	104538-4
608072	Creatine	15045-8
608073	Creatinine	14682-9
608074	Guanidinoacetate	33244-5
608075	Creatine/Creatinine	104539-2
610624	Guanidinoacetate/Creatine	105124-2
610856	Guanidinoacetate/Creatinine	104540-0
608076	Reviewed By	18771-6

Test Setup Resources

Setup Files

Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports

Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports

International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports

Test Catalog

Test Id : CRDPP

Creatine Disorders Panel, Plasma

Test Catalog

Useful For Suggests clinical disorders or settings where the test may be helpful

Genetics Test Information Provides information that may help with selection of the correct genetic test or proper submission of the test request

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

Method Name A short description of the method used to perform the test

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

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

Specimen Type Describes the specimen type validated for testing

Ordering Guidance

Additional Testing Requirements

Necessary Information

Specimen Required Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Special Instructions Library of PDFs including pertinent information and forms related to the test

Forms

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.

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

Useful For Suggests clinical disorders or settings where the test may be helpful

Genetics Test Information Provides information that may help with selection of the correct genetic test or proper submission of the test request

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Interpretation Provides information to assist in interpretation of the test results

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Clinical Reference Recommendations for in-depth reading of a clinical nature

Method Description Describes how the test is performed and provides a method-specific reference

PDF Report Indicates whether the report includes an additional document with charts, images or other enriched information

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.

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 Setup Resources

Setup Files Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Sample Reports Normal and Abnormal sample reports are provided as references for report appearance.

SI Sample Reports International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

Useful For

Suggests clinical disorders or settings where the test may be helpful

Genetics Test Information

Provides information that may help with selection of the correct genetic test or proper submission of the test request

Testing Algorithm

Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

Method Name

A short description of the method used to perform the test

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

Testing Algorithm

Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

Specimen Type

Describes the specimen type validated for testing

Specimen Required

Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Special Instructions

Library of PDFs including pertinent information and forms related to the test

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.

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

Useful For

Suggests clinical disorders or settings where the test may be helpful

Genetics Test Information

Provides information that may help with selection of the correct genetic test or proper submission of the test request

Testing Algorithm

Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

Clinical Information

Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Interpretation

Provides information to assist in interpretation of the test results

Cautions

Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Clinical Reference

Recommendations for in-depth reading of a clinical nature

Method Description

Describes how the test is performed and provides a method-specific reference

PDF Report

Indicates whether the report includes an additional document with charts, images or other enriched information

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.

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.

Setup Files

Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Sample Reports

Normal and Abnormal sample reports are provided as references for report appearance.

SI Sample Reports

International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.