Bartters syndrome
Bartter's syndrome 🧬 is a rare inherited renal tubular disorder that causes defective electrolyte handling. It is marked by hypokalaemia ⚡, metabolic alkalosis, and high renin/aldosterone — but without hypertension 🚫🩸, which is the key differentiator from other causes of secondary hyperaldosteronism.
About 📖
- Characterized by low potassium (hypokalaemia) ⚡.
- Blood pressure is normal or low 🩸⬇️.
- Pathophysiology resembles the chronic use of loop diuretics (Furosemide 💊).
Aetiology 🔬
- Genetic defect in tubular ion transport proteins.
- Most commonly affects the Na-K-2Cl co-transporter in the thick ascending limb of the loop of Henle.
- Consequences include:
- ↑ Urinary loss of K⁺ and H⁺ → hypokalaemia ⚡ + metabolic alkalosis 🧪.
- ↑ Prostaglandin production 🌀 contributing to salt wasting.
- Juxtaglomerular hyperplasia → ↑ renin & aldosterone 🔄.
Clinical Features 👶👦
- Infants: poor feeding, tiredness & lethargy 💤 due to K⁺ loss.
- Failure to thrive 🚼 common in children.
- Muscle weakness, cramps, constipation 💪⚡.
- Normal/low BP (distinguishes from hyperaldosteronism) 🩸⬇️.
- Can present as growth failure in childhood/adolescence 📉.
Investigations 🧪
- ↑ Renin & Aldosterone (secondary hyperaldosteronism).
- Hypokalaemic metabolic alkalosis ⚡🧪.
- Hypercalciuria 💧 (excess urinary calcium), may lead to nephrocalcinosis.
- Defective Na/K/Cl co-transporter confirmed genetically.
- Normal/low BP despite RAAS activation 🚫🩸.
Differential Diagnosis 🔍
- Chronic vomiting 🤮 or diarrhoea 💩.
- Diuretic abuse 💊.
- Magnesium deficiency 🧂.
- Gitelman syndrome (similar but with hypomagnesaemia and no hypercalciuria).
Management 💊
- Electrolyte supplementation: Oral Na⁺ & K⁺ to correct losses.
- Potassium-sparing diuretics: Spironolactone or Amiloride ⚡ to reduce K⁺ wasting.
- NSAIDs (e.g. Indomethacin): Reduce prostaglandin production 🌀.
- ACE inhibitors/ARBs: May be used to blunt RAAS overactivity.
Key Clinical Pearl ✨
- Bartter’s = hypokalaemia + metabolic alkalosis + high renin/aldosterone + normal/low BP 🧪⚡🩸⬇️.
- Think of it as the “genetic Furosemide effect” 💊.
