Headache caused by any disorder of homoeostasis not described above.
- Any headache fulfilling criterion C
- A disorder of homoeostasis other than those described above, and known to be able to cause headache, has been diagnosed
- Evidence of causation demonstrated by at least one of the following:
- headache has developed in temporal relation to the onset of the disorder of homoeostasis
- headache has significantly worsened in parallel with worsening of the disorder of homoeostasis
- headache has significantly improved or resolved in parallel with improvement in or resolution of the disorder of homoeostasis
- Not better accounted for by another ICHD-3 diagnosis.
Although relationships between headache and a variety of systemic and metabolic diseases have been proposed, systematic evaluation of these relationships has not been performed and there is insufficient evidence on which to build operational diagnostic criteria.