Two Adult Familial Cases of Selective Hypoaldosteronism Due to Insufficiency of Conversion of Corticosterone to Aldosterone

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A 57-year-old woman (case 1) and her daughter aged 29 (case 2) with hyperkalemia exhibited subnormal plasma aldosterone (ALD) in the face of elevated plasma renin activity. Their physical findings were normal. Their arterial blood gas analysis showed that metabolic acidosis and renal function of these cases were slightly impaired. Urinary 17-OHCS and 17-KS excretions in these cases were normal. Baseline levels of corticosterone (B) and 18-hydroxycorticosterone (18-OH-B) were clearly elevated. Plasma deoxycorticosterone (DOC), B and 18-OH-B as well as cortisol remarkable increased after ACTH injection, but the increase in plasma ALD was very small. Angiotensin II infusion in case 1 resulted in a clear rise in plasma 18-OH-B but in slight depletion of B, and no increase in ALD.
9-alpha-fludrocortisone acetate treatment was performed in case 1. Serum potassium was normalized and blood pressure elevated from 82/52 to 120/78 mmHg. Arterial blood gas analysis was corrected.
We concluded that these two cases with subnormal plasma ALD and hyperreninemia may exist as a congenital and familial abnormality of the final step of aldosterone boisynthesis due to the impairment of the conversion of B to ALD.