Hypertension and hyperkalaemia responding to bendrofluazide.

Area of Science:

• Nephrology
• Endocrinology
• Internal Medicine

Background:

• Hypertension and hyperkalemia are rare in the absence of renal failure.
• This case presents a 33-year-old man with these conditions, normal renal function, and low plasma renin activity.

Observation:

• The patient exhibited severe hypertension (160-200/90-110 mmHg) and hyperkalemia (6.0-7.0 mmol/L).
• Renal function was normal (creatinine clearance 103 ml/min), with low plasma renin activity and borderline aldosterone.
• Neither sodium deprivation nor frusemide significantly altered blood pressure, potassium, or hormonal levels.

Findings:

• Administration of bendrofluazide led to a rapid decrease in blood pressure and plasma potassium.
• Concurrently, plasma renin, aldosterone, and arginine vasopressin levels increased significantly after bendrofluazide.
• These responses suggest a primary renal tubular dysfunction affecting sodium reabsorption and potassium secretion.

Implications:

• The findings suggest a primary abnormality in renal tubular function as a cause of hypertension and hyperkalemia, even with normal renal function.
• This condition may explain some cases of essential hypertension with low plasma renin activity.
• Understanding this tubular defect could lead to new diagnostic and therapeutic strategies for specific hypertensive disorders.