Late-onset hypoparathyroidism following total thyroidectomy

Ayesha Mashadi; Elaine Soong; Khin Swe Myint

doi:10.1530/endoabs.90.EP181

Background: Post-operative hypoparathyroidism is a known complication of total thyroidectomy. It can either be transient or long-term requiring lifelong treatment. Delayed presentation of hypoparathyroidism occurring after several years of surgery is rare, with only a few cases reported in literature but can be life-threatening.

Presentation: We report a case of a 70-year-old female presenting with features of hypocalcaemia (tinnitus and tingling in her fingertips) that required hospital admission. Following were her blood.

Results– : She was treated with IV calcium gluconate, and subsequently discharged with Calvive 1gm OD and Alfacalcidol 0.5 mg BD and followed up in the metabolic bone clinic. She had a total thyroidectomy for a multinodular goitre 12 years ago, wherein she developed transient hypocalcaemia in the immediate post-operative period which resolved spontaneously. Therefore, a diagnosis of late-onset hypoparathyroidism following total thyroidectomy was confirmed.

Discussion: Hypoparathyroidism causes hypocalcaemia, hyperphosphatemia and generally has very low or undetectable PTH levels. In our case, her PTH was “normal” likely due to the remaining parathyroid tissue compensating for hypocalcaemia. Late-onset hypoparathyroidism is rare, but a few cases have been reported previously. It is likely caused by either progressive atrophy of the parathyroid glands, scar tissue formation leading to hypovascularization and progressive ischaemia, or arteriosclerotic changes leading to infarction or atrophy of the remaining parathyroid tissue. British Association of Endocrine and Thyroid Surgeons (BAETS) guidelines advise checking calcium levels within 12 hours postoperatively, but there was minimal guidance found on whether calcium levels need to be re-checked annually. Although our patient was relatively well, there have been cases reported where patients present with seizures due to late-onset hypoparathyroidism.


Tests	Results	Normal reference range
Adjusted calcium	1.75 mmol/l	2.20 - 2.60 mmol/l
Phosphate	1.61 mmol/l	0.80 - 1.50 mmol/l
25-hydroxy Vitamin D	57 nmol/l	50–120 nmol/l
PTH	1.8 pmol/l	1.6-6.9 pmol/l
Magnesium	0.85 mmol/l	0.7–1.0 mmol/l
eGFR	89 ml/min/1.73 m²

Conclusion: In patients with a history of thyroidectomy, we recommend an annual blood test for bone profile and PTH along with a thyroid function test.

Endocrine Abstracts

EP181