What the HIV-1 genotyping requisition is for
The form orders tests that guide antiretroviral choice: HIV-1 resistance genotyping across the drug classes you select, reinterpretation of an earlier genotype, plasma or proviral DNA CCR5 tropism before a CCR5 antagonist, and HLA-B*57:01 before an abacavir-containing regimen. PHO sends the specimens to the British Columbia Centre for Excellence in HIV/AIDS for testing.
It doesn’t diagnose HIV. Diagnostic serology and HIV PCR have their own requisition, and viral load is ordered separately. HLA-B*57:01 only needs doing once, since the result doesn’t change.
Who completes it
The ordering health care provider completes the whole form. You must be authorized to order laboratory tests in Ontario, and the licence number field takes your OHIP billing number, CPSO number or other college registration number. In a clinic with rotating providers, name the attending provider.
How to fill in the requisition
Submitter / Health Care Provider (HCP) Information
Give your name, licence number, facility, address, telephone and fax, and complete the Copy to fields if another provider or health unit needs the result. Check any pre-populated details against the current patient before you send it.
Patient Information
Use the names as they appear on the health card and make sure they match the specimen label exactly, or testing is cancelled. Don’t leave the health card number blank: write “not available” if it’s unknown.
Test(s) Requested
Tick each test. For resistance genotyping, select the drug classes to report. Reinterpretation can only be ordered on a specimen PHO has already genotyped, and it needs the drug classes selected. Match the test to the patient’s latest viral load: genotyping needs at least 250 copies/mL and plasma tropism at least 500.
Specimen Information
Choose plasma or EDTA whole blood to fit the test. Proviral DNA tropism and HLA-B*57:01 need EDTA whole blood, and specimens collected in plasma preparation tubes are rejected for those two. For a previously submitted viral load specimen, give PHO’s lab specimen number and result date.
Testing Indication(s) / Criteria
This section is mandatory. Tick initiating treatment, suboptimal response or treatment failure, considering a treatment change, known or suspected transmission of drug-resistant HIV-1, or pregnancy close to delivery. Use Other to explain anything outside those.
Common reasons it’s rejected or delayed
- Resistance genotyping ordered on a specimen under 250 copies/mL.
- Plasma tropism ordered on a specimen under 500 copies/mL.
- Proviral DNA tropism or HLA-B*57:01 collected in a plasma preparation tube.
- An incomplete requisition, including a missing indication.
- Incomplete or mismatched specimen labels.
- A previously submitted specimen with no PHO specimen number or result date.
Submitting and who pays
Send the specimen in a sealed biohazard bag with the requisition. PHO asks for EDTA whole blood to reach its laboratory within 24 hours of collection on ice packs. For testing on a stored specimen, fax the requisition to PHO Customer Service at the number on the form’s guide. Results go to the provider on the requisition. PHO only performs insured services under Ontario’s Health Insurance Act, so the patient isn’t charged.