Familial pseudohyperkalaemia Chiswick: a novel congenital thermotropic variant of K and Na transport across the human re cell membrane

Two families with inherited abnormalities in Na
and K transport across the red cell membrane are described.
Both presented with `pseudohyperkalaemia' as a result of
loss of K from the red cells on storage at room temperature.
Routine haematology was essentially normal, except for
macrocytosis in one family. Studies of the temperature
dependence of the passive leak to K showed a novel shoulder
pattern with a minimum at 258C, a maximum at 108C,
followed by a further fall. As in other cases of red cell-based
pseudohyperkalaemia, the abnormal temperature dependence
of this `leak' flux could be held to account for the loss of K from
the cells at room temperature. These cases represent a novel
variant of the temperature dependence of the passive leak of K
and Na across the red cell membrane, and can be classified
as a mild, non-haemolytic form of the group known