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CRDPU
88697
6 > or =100 Strongly positive Reference values
apply to all ages.
Clinical References: Homburger HA: Allergic diseases. In Clinical Diagnosis and Management by
Laboratory Methods. 21st edition. Edited by McPherson RA, Pincus MR. WB Saunders, Publ, New York,
Chapter 53, Part VI, pp. 961-971, 2007
Creatine Disorders Panel, Urine
Clinical Information: Disorders of creatine synthesis (deficiency of arginine:glycine
amidinotransferase [AGAT] and guanidinoacetate methyltransferase [GAMT]) and defect of the creatine
transporter (SLC6A8) are collectively described as creatine deficiency syndromes (CDS). AGAT and
GAMT deficiencies are inherited in an autosomal recessive manner, while the creatine transporter defect
is X-linked. All 3 disorders result in a depletion of cerebral creatine and typically present with a common
set of symptoms that include cognitive disability, speech and language delay, autistic-like behaviors, and
epilepsy. Diagnosis is possible by measuring guanidinoacetate, creatine, and creatinine in plasma and
urine. Different profiles are specific for each clinical entity. In particular, the creatine:creatinine ratio is a
useful marker of the creatine transporter defect. Treatment with oral supplementation of creatine
monohydrate is available and effective for the AGAT and GAMT deficiencies; it has not been shown to
improve outcomes in individuals with the creatine transporter defect.
Useful For: Evaluation of patients with a clinical suspicion of inborn errors of creatine metabolism
including arginine:glycine amidinotransferase deficiency, guanidinoacetate methyltransferase deficiency,
and creatine transporter (SLC6A8) defect
Interpretation: Reports include concentrations of guanidinoacetate, creatine, and creatinine, and a
calculated creatine:creatinine ratio. 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.
Reference Values:
Age Creatinine (nmol/mL) Guanidinoacetate (nmol/mL) Creatine (nmol/mL) Creatine/ Creatinine
430-5240 9-210 12-2930 0.02-0.93
32 days-23 months 313-9040 16-860 18-10490 0.02-2.49
2-4 years 1140-12820 90-1260 200-9210 0.04-1.75
5-18 years 1190-25270 40-1190 60-9530 0.01-0.96
>18 years (male) 3854-23340 30-710 7-470 0.00-0.04 Females
Age Creatinine (nmol/mL) Guanidinoacetate (nmol/mL) Creatine (nmol/mL) Creatine/ Creatinine
430-5240 9-210 12-2930 0.02-0.93
32 days-23 months 313-9040 16-860 18-10490 0.02-2.49
2-4 years 1140-12820 90-1260 200-9210 0.04-1.75
5-18 years 1190-25270 40-1190 60-9530 0.01-0.96
>18 years 1540-18050 30-760 5-2810 0.00-0.46
Clinical References: 1. Sykut-Cegielska J, Gradowska W, Mercimek-Mahutoglu S,
Stockler-Ipsiroglu S: Biochemical and clinical characteristics of creatine deficiency syndromes. Acta
Biochim Pol 2004;51:875-882 2. Stromberger C, Bodamer OA, Stockler-Ipsiroglu S: Clinical
characteristics and diagnostic clues in inborn errors of creatine metabolism. J Inherit Metab Dis
2003;26:299-308 3. Stockler S, Schultz PW, Salomons GS: Cerebral creatine deficiency syndromes:
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