Pathology Handbook

Homocysteine (for homocystinuria)

Clinical Indications

Diagnosis of homocystinuria. Plasma levels are used in preference to urine measurements as the latter may only be increased when the plasma protein binding capacity has been exceeded, thus giving rise to false negative results.

Request Form

Request on ICE

Availability

Analysed by referral laboratory if specific criteria met.

Specific Criteria

Agreed with Consultant Biochemist.

Turnaround Time

8 days

Specimen

Plasma - green-top heparin tube

Volume

1 mL minimum

Container

Vacutainer green top

Collection

Sample must be transported to laboratory and separated within 1 hour of collection.

Patients must be bled at Southend Hospital

Lab Handling

Sent to referral lab (Addenbrookes, Cambridge)

Causes for Rejection

Unlabelled or incorrectly labelled sample; delay in transit to laboratory.

Reference Range

Males:      <18 umol/L

Females: <16 umol/L