Pseudohypoaldosteronism Type I
Pseudohypoaldosteronism type I is a group of rare hereditary disorders that cause the kidneys to retain too much potassium but excrete too much sodium and water, leading to hypotension. Symptoms may result from hypotension, hypovolemia, hyponatremia, and hyperkalemia. Treatment is with a high sodium diet and sometimes fludrocortisone.
There are 3 types of pseudohypoaldosteronism:
Inheritance is autosomal recessive or autosomal dominant.
Pseudohypoaldosteronism type I resembles other forms of hypoaldosteronism except that aldosterone levels are high.
The very rare pseudohypoaldosteronism type II is not discussed here.
The autosomal recessive form tends to be severe and permanent. Infants are resistant to the effects of aldosterone due to mutations causing decreased activity of the epithelial sodium channels (ENaC) located on the luminal membrane of the collecting tubule (overactivity of ENaC causes potassium excretion and sodium retention—see Liddle Syndrome). The sodium channel in tissues other than the kidneys may be affected, leading to a miliary rash and/or complications similar to those of cystic fibrosis.