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Giant Cell Arteritis G028

Last amended 
29 June 2015
Current RMA Instruments:
Reasonable Hypothesis SOP
71 of 2012
Balance of Probabilities SOP
72 of 2012
Changes from Previous Instruments:

SOP Bulletin 162

ICD Coding:
  • ICD-9-CM Codes: 446.5
  • ICD-10-AM Codes: M31.5, M31.6

This is a type of vasculitis that most commonly involves the large and medium arteries of the head, particularly the temporal arteries.

Is specific diagnostic evidence required to apply the SOP? – No.

However definitive diagnosis generally requires a biopsy of an involved artery.

Are there sub-factors that require specific information? – No.
Additional diagnoses covered by SOP
  • Cranial arteritis
  • Horton’s disease / syndrome
  • Temporal arteritis
Unconfirmed diagnosis

If, after applying the above information, you are unable to confirm the diagnosis, you should then:

  1. seek medical officer advice about further investigation, or;
  2. generate a diagnostic report, or;
  3. re-encode the condition, if appropriate.

The following investigations may be useful in establishing the diagnosis.

  • Report of an arterial biopsy.
  • Report from treating specialist