What is included in the evaluation for hypoparathyroidism following thyroid surgery?

Updated: Feb 27, 2020
  • Author: Pramod K Sharma, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Answer

Answer

Patients having undergone a procedure where all parathyroid glands have been placed at risk for injury (total thyroidectomy, subtotal thyroidectomy, or completion thyroidectomy) should undergo evaluation for iatrogenic hypoparathyroidism. An effective method of evaluation of parathyroid function is to follow ionized calcium (or total calcium and albumin) levels in the perioperative period. If iatrogenic hypoparathyroidism is a concern, close follow-up care is warranted until calcium levels demonstrate that parathyroid function is intact.

Alternatively, a normal postoperative PTH level can accurately predict normocalcemia after thyroid surgery. Identification of at risk patients with low PTH levels will facilitate prompt calcium replacement therapy and safe early discharge from hospital. Wong, et al found that the combination of immediate postoperative PTH levels < 1.5 pmol/l and morning serum calcium < 2.0 mmol/l would accurately identify patients at risk of hypocalcemia following total thyroidectomy. [15]

Hypocalcemia may also be indicated by presence of the Chvostek sign or the Trousseau sign. The Chvostek sign is elicited by tapping the region of the facial nerve in the preauricular area resulting in facial contractions. The Trousseau sign is carpal spasm that may be elicited by inflation of a blood pressure cuff on the upper arm.

In the setting of hypocalcemia, other causes (renal failure, hypomagnesemia, medications) may be considered. Serum phosphorous levels are elevated in patients with hypoparathyroidism secondary to decreased renal excretion; this difference may help in distinguishing low PTH levels due to other etiologies of hypocalcemia (eg, hungry bone syndrome). Regardless of the etiology, the management is unchanged. If uncertainty remains 6 months after surgery, PTH levels may be checked evaluate recovery of parathyroid gland function.


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