Headache caused by any disorder of homoeostasis not described above.
A. Any headache fulfilling criterion C
B. A disorder of homoeostasis other than those described above, and known to be able to cause headache, has been diagnosed
C. Evidence of causation demonstrated by either or both of the following:
1. headache has developed in temporal relation to the onset of the disorder of homoeostasis
2. either or both of the following:
a) headache has significantly worsened in parallel with worsening of the disorder of homoeostasis
b) headache has significantly improved or resolved in parallel with improvement in or resolution of the disorder of homoeostasis
D. 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.