Lab Information Manual

Laboratory:

Clinical Biochemistry (BIOCHEMICAL GENETICS)

Test Name:

CREATINE BIOSYNTHESIS & TRANSPORT DISORDERS - (U)

Test Code: GAAU

Clinical Information:

Test Indications: Creatine biosynthesis disorders can be separated based on urine testing for guanidinoacetate (GAA) and creatine. Patients with AGAT deficiency show a low urinary GAA level while patients with GAMT have an elevated GAA level.
Analysis is performed by tandem mass spectrometry (MS-MS) with quantitation of creatine, GAA, and creatinine.

Test Approval Requirements: The “Clinical Details” section of the Biochemical Genetics Laboratory Requisition MUST be completed.

The referral lab (Greenwood Genetic Center) will not perform testing if indication (symptomatic or specific findings) is not provided.

Samples will be rejected if Clinical Details are not provided.

Collection Devices:

Preferred Device:

1 - Urine Collection 12 mL Tube

Urine Collection 12 mL Tube
Manufacturer: Sarstedt Canada Inc. (vendor)

Catalogue #:

Specimen Required:

Urine: 5.0 mL

Pediatric Urine: 1.0 mL

A fasting urine sample or first morning urine is preferred in males under 10 years of age.

Referral:

Urine: 5.0 mL

Pediatric Urine: 1.0 mL

Store and ship urine specimen frozen.

Requisition:

_SH Urine Testing Requisition (R250-10-95)

Reference Values:

Three inherited disorders are known:
AGAT (L-arginine:glycine amidinotransferase)deficiency is autosomal recessive and shows low Guanidinoacetate (GAA).
GAMT (guanidinoacetate methyltransferase)deficiency is autosomal recessive and shows elevated GAA.
CTD (creatine transporter deficiency)is X-linked and shows elevated urinary creatine/creatinine ratio.

An interpretation of results will be included on the report.

Availability:

Within 3 Weeks