Primary hyperparathyroidism--early diagnosis in patients referred for thyroid surgery

From 1986 to 1998, 190 patients presented for first-time operations for sporadic, non-malignant, non-multiple endocrine neplasia primary hyperparathyroidism. Of these patients, 54% had been classified as "asymptomatic", 41% as symptomatic and 5% as acute. One hundred and thirty-five patients (71%) were referred to us for parathyroid surgery. Fifty-five patients (29%) were referred for thyroid surgery with hitherto unknown hyperparathyroidism. This corresponds to a prevalence of primary hyperparathyroidism of 1% in patients referred for thyroid surgery (5450 patients during the same period of time).

Patients referred for parathyroid surgery (group I, n=135) were compared with patients originally referred for thyroid surgery (group II, n=55). Group II was divided into group IIa: hyperparathyroidism preoperatively biochemically evident (n=26), and group IIb: borderline biochemistry, parathyroid enlargement evident at the operation (n=29). The groups were compared regarding clinical manifestations, serum calcium and parathyroid hormone, pathologic-anatomical substrates, operative complications and outcome.

Renal, osseous and gastrointestinal manifestations were more frequent in group I than in groups IIa and IIb (P<0.05). However, cardiovascular and neuromuscular symptoms were present in groups IIa and IIb in more than one-third of patients. Patients from group IIb were younger (49+/-12 years) than patients from groups IIa (60+/-13 years) and I (60+/-14 years). Adenomas were found in 85% of group I patients, in 45% of group IIa patients and in 21% of group IIb patients (P<0.01). In all other cases, hyperplasia was confirmed histologically. Serum calcium was higher in group I (3.0+/-0.42 mmol/l) than in groups IIa (2.63+/-0.16 mmol/l) and IIb (2.46+/-0.14 mmol/l) (P<0.01). Serum PTH was higher in group I (median 11.0 pmol/l) than in groups IIa and IIb (median 7.1 and 6.4 pmol/l, respectively) (P<0.05). Postoperatively, hypercalcemia persisted in two patients (1.1%) belonging to group I, with mediastinal adenomas. Serum calcium at discharge showed no differences between groups (group I: 2.22+/-0.16; group IIa: 2.22+/-0.15; group IIb: 2.20+/-0.11 mmol/l). Recurrent laryngeal nerve paralysis occurred early (4.2% of "nerves at risk") and remained permanent (0.8% of "nerves at risk") without significant differences between groups.

Diagnostic efforts regarding parathyroid function should be mandatory before thyroid operations. "Asymptomatic" patients frequently (more than 30%) present with cardiovascular and neuromuscular, "unspecific" symptoms. Simultaneous parathyroid exploration is obvious in cases with biochemically evident primary hyperparathyroidism, but should also be performed in patients with borderline biochemistry.