There are 3 types of pseudohypoaldosteronism:
Autosomal recessive pseudohypoaldosteronism type I
Autosomal dominant pseudohypoaldosteronism type I
Pseudohypoaldosteronism type II
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.
Autosomal recessive pseudohypoaldosteronism type I
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.
Autosomal dominant pseudohypoaldosteronism type 1
Children are resistant to mineralocorticoids due to mutations of the mineralocorticoid receptor. The autosomal dominant form is usually less severe, affecting mainly the mineralocorticoid receptor in the kidney, and may resolve somewhat as children age.
Diagnosis of Pseudohypoaldosteronism Type I
Plasma renin and aldosterone levels
The diagnosis is suspected based on clinical findings of hypovolemia, high serum potassium, low serum sodium, high renin and aldosterone levels, particularly in infants with a positive family history. The diagnosis is confirmed by genetic testing.
