A 39-year-old woman who recently underwent thyroidectomy for Grave's disease complains of anxiety, muscle cramps, and poor sleep. Her medications include daily multivitamin supplements and lansoprazole for acid reflux disease. Her temperature is 36.6 C (98 F), blood pressure is 142/85 mm Hg, and pulse is 82/min. Electrocardiogram shows normal sinus rhythm with prolongation of the corrected QT interval to 510 msec (normal

Question

A 39-year-old woman who recently underwent thyroidectomy for Grave's disease complains of anxiety, muscle cramps, and poor sleep.  Her medications include daily multivitamin supplements and lansoprazole for acid reflux disease.  Her temperature is 36.6 C (98 F), blood pressure is 142/85 mm Hg, and pulse is 82/min.  Electrocardiogram shows normal sinus rhythm with prolongation of the corrected QT interval to 510 msec (normal <460 msec).  Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

Post-surgical hypoparathyroidism can occur during thyroidectomy or from the removal of 3 1/2 parathyroid glands due to parathyroid hyperplasia. Hypocalcemia is the resultant condition of the hypoparathyroidism and the most common complication of thyroidectomy. Patients with hypocalcemia can be asymptomatic at initial presentation (found incidentally) or may complain only of nonspecific symptoms (eg, fatigue, anxiety, depression). Involuntary contractions (tetany) involving the lips, face, and extremities and seizures are seen in severe hypocalcemia. Electrocardiogram may show QT-interval prolongation. (Choice A) Hyperkalemia is not a common postoperative complication of thyroidectomy. (Choices C and D) Persistent hypothyroidism (not hyper) can be seen post-thyroidectomy and can cause hyponatremia without thyroid hormone supplementation. Prolonged QT interval is not seen with hypothyroidism/hyponatremia. (Choice E) Vitamin D toxicity is associated with hypercalcemia, which results in shortened QT interval. Educational objective: Hypoparathyroidism (parathyroid hormone deficiency) is characterized by low calcium and elevated phosphorus levels in the presence of normal renal function. Causes of hypoparathyroidism include post surgical, autoimmune parathyroid destruction, and defective calcium-sensing receptor. Hypocalcemia is the most common complication seen post thyroidectomy. References: Prognostic significance of intraoperative PTH test for the development of post-thyroidectomy hypocalcaemia. (http://www.ncbi.nlm.nih.gov/pubmed/22708469)

A 39-Year-Old Woman Who Recently Underwent Thyroidectomy for Grave's Disease