To minimise disruption to laboratory workflow, the Integrated Laboratory does not routinely encourage the use of add-on tests. In addition, the accuracy of some test results may be affected by specimen storage conditions and the time elapsed between sample collection and receipt of the add-on request.

Where feasible, the laboratory will accommodate add-on requests provided all of the following criteria are met.

Criteria for Acceptance 

An add-on test request may be accepted only if all of the following criteria are met:

• The patient is an inpatient.

• Only one add-on request is permitted per specimen.

• The original laboratory request has already been registered in the Laboratory Information System (LIS).

• The Total Laboratory Automation (TLA) system is operating normally (i.e. not during downtime).

• The add-on request is within the specified acceptance time limit (refer below).

• The requested test is not included in the list of tests unsuitable for add-on requests (refer below).

• The specimen remains suitable for analysis (e.g. adequate volume, not haemolysed, not otherwise compromised).

• The request is not urgent. Add-on tests are processed with routine priority only. If an urgent result is required, a new specimen should be collected and submitted as an urgent request.

• The requested test is not within the established Minimum Retesting Interval (MRI). If repeat testing is clinically justified, the add-on request must be discussed with the Integrated Laboratory Medical Officer/Chemical Pathologist (office hours) or the On-Call Pathologist (after hours).

• A valid add-on request form is received.

Tests Unsuitable for Add-on Requests

The following tests cannot be requested as add-on tests:

1. Labile / Unstable Analytes (rapidly change after collection)

• Ammonia

• Lactate

• Blood Gas

2. Tests Requiring Special Handling

• Therapeutic Drug Monitoring (TDM)

3. Tests Requiring Separate Specimen Tube or Specific Collection Requirements

• Glucose

• Procalcitonin (PCT)

• Parathyroid Hormone (PTH)

• HbA1c

• Urine based tests

Note: This list is not exhaustive. The laboratory reserves the right to decline any add-on request where specimen suitability or analytical requirements cannot be met.

Procedure for Requesting an Add-on Test

1. Contact the Integrated Laboratory (Ext. 8241/8242) to request an add-on test.

For most add-on requests, the request may be made directly to the Medical Laboratory Technologist (MLT). 

However, consultation with a Chemical Pathologist is required for:

• Non-routine tests

• Tests not included in the approved add-on test list

• Critical or exceptional cases where the add-on request does not meet the established acceptance criteria

2. Provide the following information:

• Original Request Laboratory ID

• Patient identification

• Test(s) requested

3. Laboratory personnel will perform a preliminary assessment of the request.

4. If the request is considered suitable, complete a new laboratory request form. The standard mandatory patient and request information must be completed. In addition, the following information specific to the add-on request must be included:

• Clearly indicate "ADD-ON REQUEST" and “Original specimen Laboratory ID” on the form

• Additional test(s) requested

• Details of communication with laboratory staff (name of laboratory personnel, date and time).

• Name, signature and official stamp of the requesting clinician.

5. Submit the completed request form to the laboratory immediately.

Processing of Add-on Requests

Accepted add-on requests will be processed with the same priority as routine inpatient specimens.

Submission of an add-on request does not guarantee that testing will be performed. The laboratory reserves the right to reject an add-on request if the specimen is no longer suitable for analysis, including but not limited to insufficient specimen volume, specimen deterioration, or failure to meet analytical requirements.

If the add-on request cannot be processed, a comment stating the reason will be added to the patient report.