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:
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.
Аутосомно-рецесивний псевдогіпоальдостеронізм I типу
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.
Аутосомно-домінантний псевдогіпоальдостеронізм 1 типу
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.
Treatment of Pseudohypoaldosteronism Type I
High-sodium diet and sometimes fludrocortisone
A high-sodium diet helps maintain volume and BP and increases excretion of potassium. If diet is ineffective, fludrocortisone 0.5 to 1.0 mg orally twice/day or 1 to 2 mg orally once/day can be given.
