Pathology Handbook

Urinary Organic Acids

Clinical Indications

Most organic acids are cleared efficiently by the kidney and urine is used for screening.

Plasma is limited to monitoring methylmalonic acidaemias.

The circumstances under which samples is collected is of critical importance since in cases of an incomplete metabolic block, characteristic metabolites may only be detected at times of metabolic decompensation (e.g. infection).

Request Form 

Request on ICE

Availability

Analysed by referral laboratory if specific criteria met.

Specific Criteria

Requests must be accompanied by full clinical details and information about any medication

The signs and symptoms will, to a large extent, determine the tests requested and it is therefore VITAL to have adequate clinical information. These tests may sometimes be URGENT as the disorder may be life threatening, and close liaison with clinical staff is therefore essential.

Patient Preparation

Samples should be collected when the patient is unwell and before treatment or a change in diet alters the pattern of metabolites.
A fasting or pre-breakfast urine is required for investigation of fatty acid oxidation defects.

Turnaround Time

2 weeks

Specimen

Urine

Volume

5.0 ml in a white-capped universal

Container

Urine bottle white top

Lab Handling

Sent to referral laboratory (Addenbrookes, Cambridge)

Collection

Samples should be transported to laboratory immediately.

Causes for Rejection

Unlabelled sample.
Not meeting specific criteria for analysis. 
Delay in sample reaching laboratory

Reference range & interpretation

Qualitative results reported with interpretation