Malignant prolongation of the QTc interval due to severe vitamin D deficiency: an unusual presentation

BMJ Case Rep. 2020 Dec 15;13(12):e237157. doi: 10.1136/bcr-2020-237157.


Long QT syndrome with Torsades de Pointes (TdP) is a life-threatening polymorphic ventricular arrhythmia. The corrected QT (QTc) prolongation >500 milliseconds (ms) has been associated with TdP. Hypocalcaemia due to severe vitamin D deficiency is an uncommon cause of acquired long QT. We hereby present a case of a 40-year-old woman with sensorineural deafness and having symptoms of palpitations and presyncope. She had a QTc interval of 556 ms (reference range, QTc 451-470 ms in adult healthy woman) on 24-hour Holter analysis. Genetic analysis for congenital long QT syndrome was negative. She was diagnosed with severe hypocalcaemia secondary to severe vitamin D deficiency. After treatment with intravenous calcium gluconate, followed by oral vitamin D and calcium supplementation, the QTc became normalised and no further episode of palpitations or presyncope occurred. The causes of vitamin D deficiency was due to inadequate exposure to sunlight and a strict vegan diet.

Keywords: arrhythmias; calcium and bone; endocrine system; medical education; pacing and electrophysiology.

Publication types

  • Case Reports

MeSH terms

  • Adrenergic beta-1 Receptor Antagonists / therapeutic use
  • Adult
  • Calcium / therapeutic use
  • Calcium Gluconate / therapeutic use
  • Electrocardiography, Ambulatory / methods
  • Female
  • Humans
  • Hypocalcemia / diagnosis
  • Hypocalcemia / drug therapy
  • Hypocalcemia / etiology
  • Long QT Syndrome / diagnosis*
  • Long QT Syndrome / drug therapy
  • Long QT Syndrome / etiology*
  • Metoprolol / therapeutic use
  • Vitamin D / therapeutic use
  • Vitamin D Deficiency / complications*
  • Vitamin D Deficiency / diagnosis*
  • Vitamin D Deficiency / drug therapy
  • Vitamins / therapeutic use


  • Adrenergic beta-1 Receptor Antagonists
  • Vitamins
  • Vitamin D
  • Metoprolol
  • Calcium Gluconate
  • Calcium