Hyperkalemia is caused by-

-Mutations of WNK1 and WNK4 (members of a family of serine-threonine kinases) have been shown to cause the rare familial autosomal dominant disease called Gordon's syndrome (also known as pseudohypoaldosteronism type II). Wild-type WNK1 and WNK4 inhibit the thiazide-sensitive Na-Cl co-transpoer in the distal tubule. - Hyperkalemia, another hallmark of this syndrome, might be a function of diminished sodium delivery to the coical collecting tubule (sodium reabsorption provides the driving force for potassium excretion, which is mediated by the renal outer medullary potassium channel ROMK). Alternatively, the same mutations in WNK4 that result in a gain of function of the Na-Cl co-transpoer, might inhibit ROMK activity , resulting in hyperkalemia, as suggested by recent genetic studies. Ref Davidson 23rd edition pg 369