Thyroid pathology associated with primary hyperparathyroidism

Thyroid carcinoma and benign thyroid disease associated with primary hyperparathyroidism (PHPT) have been well described. With the developing trend toward minimally invasive parathyroidectomy without intra-operative thyroid gland palpation, thyroid pathology may be missed. The authors consider it timely to revisit the issue of thyroid pathology found at neck exploration for PHPT.

A retrospective review of all cases of neck exploration for PHPT between 1993 and 1998 at Liverpool Hospital was undertaken.

There were 65 patients in the study group (44 women, 21 men; mean age: 59 years). The most common indication for surgery was asymptomatic hypercalcaemia. The mean pre-operative calcium level was 2.9 mmol/L and the mean parathyroid hormone (PTH) level was 17 pmol/L. There were 26 cases (40%) of coexistent thyroid pathology. Ten cases (15%) were of mild multinodular change, seven cases (11%) were of severe multinodular change requiring thyroidectomy, three cases (4%) were nodules secondary to Hashimoto's thyroiditis and six cases (10%) were suspicious nodules that proved to be either adenomas (n = 3) or carcinomas (n = 3) following excision. There were four papillary carcinomas detected in the present series with a mean metastases, age, completeness of excision, invasion size (MACIS) score of 4.92.

A 25% association of significant thyroid pathology with PHPT is reported. Despite pre-operative tests there were two cases (4%) of thyroid carcinoma where the decision to resect the thyroid gland was made following intra-operative thyroid gland palpation. One of these two papillary carcinoma patients would have fulfilled criteria for minimally invasive parathyroid surgery. When evaluating results of minimally invasive parathyroid surgery one must be aware of the potential for missed thyroid pathology.