Makindo Medical Notes

Related Subjects: | Metabolic Acidosis | Lactic Acidosis | Acute Kidney Injury (AKI)

About 🧾

• Gitelman’s Syndrome: A rare inherited tubulopathy of the distal convoluted tubule, caused by mutations affecting the thiazide-sensitive NaCl cotransporter (SLC12A3 gene).
• Often described as a “benign Bartter’s variant” but has key biochemical differences.
• Autosomal recessive inheritance → manifests usually in late childhood or adulthood.

Clinical Features 👩‍⚕️

• 💤 Chronic fatigue, weakness, and muscle cramps due to electrolyte imbalance.
• 🌙 Nocturia and polyuria (salt wasting leads to impaired concentrating ability).
• 📉 Hypotension or low–normal blood pressure (despite RAAS activation).
• Symptoms often milder than Bartter’s and sometimes discovered incidentally on blood tests.

Investigations 🔬

• Hypokalaemia 🟡: Potassium loss → muscle weakness, cramps, arrhythmia risk.
• Metabolic Alkalosis 🧪: Due to renal hydrogen ion loss.
• Salt Wasting 🧂: Renal sodium loss → mild volume depletion.
• Hypomagnesaemia 🔵: Characteristic and often symptomatic (tremors, cramps).
• Urinary Chloride ↑: Consistently high, differentiates from surreptitious diuretic use.
• Calcium: Unlike Bartter’s, Gitelman’s is associated with hypocalciuria (↓ urinary calcium).

Key Differentiation 🆚 Bartter’s

• Bartter’s: Presents earlier in life, with hypercalciuria and often nephrocalcinosis.
• Gitelman’s: Later onset, with hypocalciuria and prominent hypomagnesaemia.

Management ⚕️

• 💊 Electrolyte Replacement: Oral potassium and magnesium supplements are cornerstone therapy.
• 🥤 Liberal salt intake to counteract chronic salt wasting.
• 🛡️ Potassium-sparing agents: Spironolactone, eplerenone, or amiloride to reduce renal K⁺ loss.
• 🚫 NSAIDs: Unlike Bartter’s syndrome, NSAIDs are not useful in Gitelman’s.

Clinical Pearl 💡

Think of Gitelman’s in a young adult with chronic cramps, fatigue, hypokalaemia, and low urinary calcium. 🔑 “Hypo-K, Hypo-Mg, Hypocalciuria” = Gitelman’s.