Turnaround times
The quoted turnaround time is from sample receipt in the laboratory, to results authorisation in the Laboratory Information Management system. The times do not include transport of specimen to the laboratory or the administrative process to print and post/email reports. Service users must allow for transport and reporting time when ordering tests.
Clinical background:
For investigation of suspected metabolic disorders of creatine synthesis or transport including guanidinoacetate methyltranferase (GAMT) deficiency, arginine:glycine amidinotransferase (AGAT) deficiency and creatine transporter deficiency. Plasma guanidinoacetate is also used in monitoring patients with these disorders. N.B: to investigate the X-linked creatine transport defect, a urine sample is required for measurement of creatine/creatinine ratio.
Specimen container paediatric:
Lithium heparin plasma Serum
Specimen container adult:
Lithium heparin plasma Serum
Minimum volume paediatric:
0.5 mL
Minimum volume adult:
0.5 mL
Sample stability:
Guanidinoacetate and creatine are stable in plasma at ambient temperature for at least 2 weeks.
Transport requirements:Send to laboratory at ambient temperature.
Send to laboratory at ambient temperature.
Reference ranges:
Creatine
Age ≤ 10 years 41 – 115 µmol/L
Age > 10 years 8 – 89 µmol/L
Guanidinoacetate
Age ≤ 10 years 0.55 – 2.36
Age > 10 years 0.85 – 3.31