Pseudohypoaldosteronism: decreased aldosterone levels with age without significant change in urinary sodium excretion

To clarify age-related changes in the plasma renin activity (PRA)-aldosterone (ALDO) system in relation to urinary sodium (Na) excretion in pseudohypoaldosteronism type I (PHA), we followed a patient with PHA serially by measuring the hormonal balance and urinary electrolyte excretion for 5 years. The patient was diagnosed as PHA mainly on the basis of extremely high PRA (170 ng/ml/h) and ALDO (1670 ng/dl) despite massive urinary Na excretion, a normal ALDO/PRA ratio (mean value = 11), and the ineffectiveness of 9 alpha-fluorocortisol (Florinef) to reduce urinary Na excretion and PRA-ALDO. The pattern of reduction in PRA-ALDO with age in this patient was almost identical with that of normal infants and children and was most remarkable during the first 18 months of life. During this period, there were statistically significant correlations between age and each of the following values: PRA (r = -0.753, n = 9, P less than 0.05), ALDO (r = -0.736, n = 11, P less than 0.01) and urinary ALDO excretion (r = -0.840, n = 9, P less than 0.01). But the reduction of PRA-ALDO in this patient was not the result of increased urinary Na excretion with age. Although PRA and ALDO values in this patient did decrease with age, they were still high compared with age-matched controls, suggesting a marginal state of Na balance. Thus, we conclude that PRA-ALDO levels in PHA decrease with age in the same pattern as in normal infants and children without a significant change in urinary Na excretion, possibly through increased renal conservation of Na, the mechanism of which should be clarified in a future study.