We report a child with primary renal tubular alkalosis who had hypokalemia, profound hyperreninemia, and hypoaldosteronism. A 14-year-old girl presented with short stature and delayed puberty. Laboratory evaluation disclosed hypokalemia, hypochloremia, hypomagnesemia, alkalosis, hypocalciuria, and a markedly elevated rennin at 2859 ng/mL/h and a suppressed aldosterone at 2.5 ng/dL. Subsequently, as the serum potassium normalized, renin levels gradually declined (16.78 ng/mL/h) and, despite this renin reduction, aldosterone levels progressively increased (61.7 ng/dL). The patient's clinical course highlights the preeminent role of potassium, as a direct regulator of aldosterone synthesis, versus the indirect action of renin. This observation suggests potassium is by and large a major regulator of aldosterone synthesis in renal salt-wasting disorders.