The order of the nephron defects in Bartter, Gitelmann and Liddle syndrome follows alphabetical order.
Bartter: Thick ascending LOH
Gitelmann: Distal tubule
Liddle: Collecting duct
a. Bartter syndrome: Thick ascending Loop of Henle (LOH)
- Defect in Na-2K-Cl transporter (like loop diuretics)
- NaCl wasting, Hypercalciuria and mild hypomagnesemia
Mnemonic: Loop diuretics lose calcium
b. Gitelmann syndrome: Distal tubule
- Defect in Na-Cl co-transporter (like thiazide diuretics)
- NaCl wasting, Hypocalciuria and Hypomagnesemia
Mnemonic: Thiazides preserve calcium
c. Liddle syndrome: Collecting duct
- Continuous activation of ENaC in collecting duct leading to increased Na absorption
- Early and severe hypertension with low renin and aldosterone
- Hypokalemia and metabolic alkalosis
- Amiloride or triamterene block ENaC (basis of treatment)
Important points to remember:
- All of these cause hypokalemia and metabolic alkalosis.
- Bartter and Gitelmann causes normotension or hypotension while Liddle causes hypertension.
- Bartter’s syndrome causes hypercalciuria while Gitelmann’s syndrome causes hypocalciuria.
- Gitelmann’s syndrome causes hpomagnesemia.
- NSAIDs reduce polyuria and salt wasting in Bartter’s syndrome (increased renal PGE2 production in Bartter’s).
- Bartter’s and Gitelmann’s are autosomal recessive (AR) while Liddle’s is autosomal dominant (AD).
- In Bartter’s and Gitelmann’s there is secondary hyperaldosteronism and in Liddle’s, there is hypoaldosteronism.