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:
Urinary organic acid analysis is a first line investigation in a wide range of inborn errors of metabolism. This large class of genetic diseases involves amino acid, carbohydrate and lipid metabolism, with accumulation of specific organic acids detected in urine often indicative of a metabolic inhibition or block. These disorders have a wide range of clinical presentations either due to accumulation of substances which are toxic or interfere with normal function, or due to the effects of reduced ability to synthesize essential compounds.
Qualitative urinary organic acid analysis allows the diagnosis of organic acid disorders and some fatty acid oxidation defects.
Specimen container paediatric:
Plain universal container
Specimen container adult:
Plain universal container
Minimum volume paediatric:
3 mL urine
Minimum volume adult:
5 mL urine
Special requirements:
In the event of a particular presenting syndrome e.g. hypoglycaemia or metabolic acidosis it is important to obtain samples as near to episodes as possible.
Provide full drug history.
Sample stability:
Sample should be sent frozen and stored frozen in the laboratory
Transport requirements:
Ward: Ambient temperature to the laboratoryExternal hospitals: Send frozen sample to the RVI
Interpretation :
Urinary organic acid analysis is reported as an interpretive comment, and any suggested follow-up testing will be included. Any clinically urgent results will be telephoned to the requesting clinician or referral laboratory.
Over 100 urinary organic acids are usually detected by the analysis, however only specific abnormalities detected will be commented upon. Clinical details are essential for meaningful organic acid interpretation.
Some drug metabolites may be detected and identified (eg, Valproate, Paracetamol), however many other drugs may also interfere in the analysis therefore a full drug history is helpful to identify these compounds and avoid unnecessary additional investigation. Dietary factors can also significantly affect results so details of any specific diet (eg, medium chain triglyceride containing formula, protein restricted diet) should also be included with the request.
Reference ranges:
Reported as an interpretative comment.
Factors affecting result:
Clinical details are very important for the interpretation of organic acid profiles. Drugs and dietary factors may interfere in the interpretation. Please provide details of any medication or specific diet.
If creatinine < 1 mmol/L, sample is too dilute for reliable analysis. Bacterial contamination is likely to affect reliability of results. All samples are tested for nitrate and pH to identify the presence of bacterial contamination.