Postoperative hypocalcemia is a common and most often transient event after extensive thyroid surgery. It may reveal iatrogenic injury to the parathyroid glands and permanent hypoparathyroidism. We prospectively evaluated the incidence of hypocalcemia and permanent hypoparathyroidism following total or subtotal thyroidectomy in 1071 consecutive patients operated during 1990-1991. We then determined in a cross-sectional study which early clinical and biochemical characteristics of patients experiencing postoperative hypocalcemia correlated with the long-term outcome. Postoperative calcemia under 2 mmol/l was observed in 58 patients (5. 4%). In 40 patients hypocalcemia was considered severe (confirmed for more than 2 days, symptomatic or both). At 1 year after surgery five patients (0.5%) had persistent hypocalcemia. We found that patients carried a high risk for permanent hypoparathyroidism if fewer than three parathyroid glands were preserved in situ during surgery or the early serum parathyroid hormone level was /= 4 mg/dl under oral calcium therapy. When one or more of these criteria are present, long-term follow-up should be enforced to check for chronic hypocalcemia and to avoid its severe complications by appropriate supplement therapy.

The thyrotropin receptor (TSHR), a member of the large family of G protein-coupled receptors, controls both the function and growth of thyroid cells via stimulation of adenylyl cyclase. We report two different mutations in the TSHR gene of affected members of two large pedigrees with non-autoimmune autosomal dominant hyperthyroidism (toxic thyroid hyperplasia), that involve residues in the third (Val509Ala) and seventh (Cys672Tyr) transmembrane segments. When expressed by transfection in COS-7 cells, the mutated receptors display a higher constitutive activation of adenylyl cyclase than wild type. This new disease entity is the germline counterpart of hyperfunctioning thyroid adenomas, in which different somatic mutations with similar functional characteristics have been demonstrated.

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From 1964 to 1989, bone metastases were found in 28 of 600 patients operated on for differentiated thyroid carcinoma. Bone metastasis was the presenting symptom in 15 (54%) patients, was detected from the initial symptom in 4 (14.5%) patients, and occurred subsequently in 9 (32%) patients, with an average lag time of 4.5 years after surgical treatment. Pathological pattern of the thyroid cancer was follicular in 26 (93%) patients and papillary in 2 (7%) patients. Bone metastatic involvement was multiple in 21 (75%) patients and associated with other synchronous or metachronous distant metastases in 13 (46%) patients, especially in the lung (10 patients) or the brain (3 patients). The primary treatment of thyroid carcinoma was total thyroidectomy in all 28 patients, with additional modified neck dissection in 8 patients. All 15 patients presenting with symptoms had bone metastases demonstrated by x-ray studies. Six of the bone metastases only took up radioactive iodine 6 weeks after total thyroidectomy, as did 2 of 4 bone metastases detected at initial observation and 4 of 9 metachronous bone metastases. All 12 patients with functioning bone metastases were given radioactive iodine therapy; 4 of the metastases were surgically resected. Only 2 patients with bone metastases showed a complete response after an ablative dose of I-131; none of the metastases had been demonstrated by x-ray studies. Radioactive iodine therapy cures no more than 17% of patients with bone metastases taking up radioactive iodine and 7% of all patients with bone metastases. All patients cured of bone metastases were given radioactive iodine, either alone, or combined with other treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Pseudohypoparathyroidism Ia (PHP Ia) is characterized by resistance to PTH and many other stimuli because of deficiency of stimulatory G protein alpha-subunit. To determine the incidence, natural history, and mechanism of C cell dysfunction in PHP, calcitonin assays were performed in six patients with PHP Ia and four with pseudopseudohypoparathyroidism from three unrelated families. Controls included healthy subjects and patients with PHP Ib or hypoparathyroidism. The mean basal level of calcitonin was higher in PHP Ia patients than in controls (95.3 +/- 112.7 vs. 3.7 +/- 2.4 pg/mL; P = 0.005; n < 10). In PHP Ia patients, calcitonin levels rose over the normal range (30 pg/mL) after pentagastrin infusion in five patients and remained normal in one. Familial medullary thyroid carcinoma was clinically, biologically, and ultrasonographically ruled out over a mean follow-up exceeding 3 yr. Genomic screening for RET protooncogene mutations failed to reveal any anomaly. The calcitonin infusion test, which induced a significant increase in plasma cAMP in controls 30 and 60 min after infusion, failed to produce this response in PHP Ia patients, suggesting that the action of calcitonin was specifically impaired. PHP Ia may therefore be an independent etiology of hypercalcitoninemia and hyperresponsiveness to pentagastrin infusion.