This notice is to advise that Awanui Laboratories in Canterbury are changing the reference ranges to the D-dimer assays in line with current guidelines and to align ranges across the Awanui group.
Date of effect: 27th October 2026
The recommendation is to use an age adjusted range and is evidence based in the following articles:
1. Diagnostic accuracy of conventional or age adjusted D-dimer cut-off values in older patients with suspected venous thromboembolism: systematic review and meta-analysis (Henrike J Schouten et al. BMJ 2013;346 doi: http://dx.doi.org/10.1136/bmj.f2492)
2. Age-adjusted D-dimer cutoff levels to rule out pulmonary embolism: the ADJUST-PE study (Marc Righini et al. JAMA 2014 Mar 19;311(11):1117-24)
The new reference ranges are therefore:
| Age | Reference range(ug/L) | Telephone criteria(ug/L) |
| <50 years | 500 | >500 |
| 51-60 years | <600 | >600 |
| 61-70 years | <700 | >700 |
| 71-80 years | <800 | >800 |
| 81-90 years | <900 | >900 |
| 91 years and over | <1000 | >1000 |
‘Positive’ D-dimer results will only be phoned out of hours AND if the requestor has indicated they wish to be called and supplied a phone number for a medical professional who can manage the result at all hours (i.e., clinician mobile).