Overview
This lecture covers Liddle syndrome, focusing on its genetic inheritance, pathophysiology, key clinical features, and treatment.
Inheritance and Pathophysiology
- Liddle syndrome is inherited in an autosomal dominant manner.
- The mutation affects the collecting duct of the nephron, increasing sodium reabsorption in the collecting tubules.
- Increased sodium reabsorption leads to water retention and elevated blood pressure.
- As a result, renin and aldosterone levels are decreased.
Clinical Features
- Patients present with hypertension (high blood pressure).
- There is metabolic alkalosis (blood becomes too basic).
- Hypokalemia (low potassium) occurs due to potassium loss in the urine.
- Despite similarities to hyperaldosteronism, aldosterone levels are low or nearly undetectable.
Treatment
- Liddle syndrome is treated with amiloride, a potassium-sparing diuretic.
Key Terms & Definitions
- Autosomal dominant — a pattern of inheritance where only one mutated gene is needed for the condition to develop.
- Collecting duct — part of the nephron where final urine concentration occurs; affected in Liddle syndrome.
- Metabolic alkalosis — a condition where body fluids have excess base (alkali).
- Hypokalemia — abnormally low blood potassium levels.
- Aldosterone — a hormone that increases sodium reabsorption and potassium excretion in the kidneys.
- Amiloride — a medication that blocks sodium reabsorption and spares potassium in the kidneys.
Action Items / Next Steps
- Review nephron function and the role of the collecting duct.
- Study the differences between Liddle syndrome and hyperaldosteronism.
- Read about amiloride’s mechanism of action.