Endocrine Abstracts

An elective total thyroidectomy was performed on a previously well 45-year-old nurse for toxic multinodular goitre. The operation was uneventful and the patient was discharged. She was re-admitted two days after the operation, with paraesthesia and muscle spasms affecting the face and hands. She was found to be hypocalcaemic, corrected calcium 1.83 mmol/l. She was treated with intravenous calcium gluconate, oral calcium and 1-alpha calcidol. Parathyroid levels were undetectable.

Over the following days she continued to have multiple episodes of spontaneous severe carpo-pedal spasm with many of the episodes progressing to full tetany, with opisthotonus. The episodes were not associated with hypocalcaemia or hypomagnesaemia, but they were terminated with intravenous calcium gluconate.

The episodes continued despite the serum corrected calcium levels being elevated at 2.75 mmol/l. On the eighth post operative day, the authors witnessed an episode of severe tetany which was found to be associated with hyperventilation. Arterial blood gas analysis during the episode showed a respiratory alkalosis (pH 7.59 pO2 13.3 pCO2 3.5 bicarbonate 25). The patient described the episodes being precipitated by a constricting feeling in her throat. Subsequent fibro-optic laryngoscopy demonstrated a paralysed left vocal fold, due to recurrent laryngeal nerve palsy.

The patient was given an explanation of the condition together with breathing exercises. She had no further episodes of tetany and was discharged. She was well when followed up in clinic. A diagnosis was made of episodic tetany caused, initially, by post-operative hypoparathyroidism, and subsequently by hyperventilation syndrome, complicating recurrent laryngeal nerve palsy, post total thyroidectomy.