Calcium unresponsive hypocalcemic tetany: gitelman syndrome with hypocalcemia

Area of Science:

• Nephrology
• Genetics
• Endocrinology

Background:

• Gitelman syndrome (GS) is an autosomal recessive renal tubular disorder.
• GS typically presents with hypokalemia, hypomagnesemia, hypocalciuria, metabolic alkalosis, and hyperreninemic hyperaldosteronism.
• Normal serum calcium is usually observed in Gitelman syndrome.

Purpose of the Study:

• To report a case of Gitelman syndrome presenting with hypocalcemic tetany.
• To highlight the importance of considering hypocalcemia in the differential diagnosis of tetany.
• To emphasize the diagnostic approach for Gitelman syndrome.

Main Methods:

• A case report of a 28-year-old woman with recurrent tetany.
• Clinical evaluation including physical examination, laboratory tests (serum electrolytes, arterial blood gases), and a thiazide loading test.
• Exclusion of other causes of hypocalcemia and electrolyte imbalances.

Main Results:

• The patient presented with hypocalcemic tetany, hypokalemia, hypomagnesemia, metabolic alkalosis, and hypocalciuria.
• The thiazide loading test showed blunted fractional chloride excretion, aiding in the differentiation from Bartter's syndrome.
• Treatment with spironolactone, magnesium, calcium, and potassium supplementation led to symptomatic improvement.

Conclusions:

• Hypocalcemia, though rare, can be a presenting feature of Gitelman syndrome.
• In patients with tetany, comprehensive electrolyte and acid-base assessment is crucial, including magnesium, potassium, and arterial blood gases.
• Prompt diagnosis and management of Gitelman syndrome can prevent recurrent episodes of tetany.