The Leeds Teaching Hospitals NHS Trust

Creatine / GAA

For the investigation of creatine biosynthesis disorders by measurement of creatine and its precursor guanidinoacetate (GAA) in blood and urine.Three disorders of creatine biosynthesis have been described - Guanidinoacetate methyltransferase (GAMT) deficiency, arginine:glycine amidinotransferase (AGAT) deficiency and x-linked creatine transporter defect (SLC6A8).

Presentation of the three creatine synthesis disorders is neurological with psychomotor retardation, developmental delay, speech delay and epilepsy being the most common features.

Contact Biochemical Genetics laboratory for further advice if required.

Tube Plain Universal (urine) / Lithium Heparin (plasma)
ID 29939
Availability Weekdays
Additional Information Urine is essential for the investigation of a creatine transporter defect.
Turn Around 30 days
Send to Specialist Laboratory Medicine
Block 46
St James hospital
Beckett Street
Collection Con Minimum volume: 0.1 mL

Instructions for lab: On receipt of samples, urine samples should be frozen and lithium heparin blood samples should be spun down immediately, plasma separated and then frozen (urine/plasma must be frozen with 2 hours of collection). Please record the time the sample is frozen on the request card.

Send to Block 46. If storage required (overnight or over the weekend) store in freezer (-20°C).

Please discuss with Biochemical Genetics lab prior to rejecting any samples.
Frequency Once a month
Sample REQ For initial investigations both urine and plasma should ideally be sent. For monitoring of known GAMT or AGAT deficiency patients only a plasma sample is required. Please send samples ASAP to the lab.
Ref. Range Notes Age related referenge range supplied on the report as appropriate. Contact Biochemical Genetics laboratory for further advice if required.
Units Urine: µmol/mmol creatinine. Plasma: µmol/L.
Telepath Urine creatine/ GAA: CRSU1J, Plasma creatine/ GAA: CRSP1J
ICE Codes Urine creatine/ GAA: LCRSU, Plasma creatine/ GAA: LCRSP