Biomedical subjects

M Shabtay

Publications and source records attributed to M Shabtay.

3 recordsLinked to original sources

PubMed1995

Correct preoperative localization: does it permit a change in operative strategy for primary hyperparathyroidism?

BACKGROUND: A meticulous bilateral neck exploration by an experienced endocrine surgeon offers a high cure rate with low morbidity for patients with primary hyperparathyroidism. The advent of localizing studies raises the possibility of unilateral neck exploration. The cost-effectiveness of preoperative localizing studies and unilateral neck exploration in primary hyperparathyroidism are controversial issues. This study was designed to determine the risks of missing a contralateral pathologic parathyroid gland in patients with preoperative localization that was confirmed at neck exploration. METHODS: Preoperative studies (ultrasonography, nuclear radioactive imaging scan, or both) were performed in 79 patients with primary hyperparathyroidism. In 58 patients a definite localization of an enlarged parathyroid gland was confirmed at operation. All patients underwent a meticulous bilateral neck exploration. RESULTS: Unilateral neck exploration was feasible only in 73.4% of the patients, according to our localizing modalities, and an additional enlarged parathyroid gland on the contralateral side, not detected before operation, was revealed in five patients (8.6%). False-positive rates were 1.7% for ultrasonography and 13% for scan. CONCLUSIONS: These results indicate an unacceptably high surgical failure rate for unilateral neck exploration guided by preoperative localizing studies compared with a bilateral neck exploration by an experienced endocrine surgeon, questioning the cost-effectiveness of preoperative localizing studies.

Adenoma↗

PubMed1992

Non-autonomy of parathyroid hormone secretion in acute primary hyperparathyroidism.

A patient with acute primary hyperparathyroidism treated with mithramycin preoperatively, underwent neck exploration and two enlarged parathyroid glands were excised: one huge adenoma (6g) and another smaller gland. Mithramycin was administered preoperatively to lower life-threatening hypercalcaemia, and parathyroid slices from the huge adenoma removed at surgery were submitted in vitro to various calcium concentrations in the media to determine the influence of calcium on parathyroid adenoma secretory pattern in acute primary hyperparathyroidism. Mithramycin induced a significant decline in calcium levels and significant elevations of calciotrophic hormones (intact PTH, mid-region specific PTH, calcitonin and calcitriol). Significant suppression in PTH output in vitro was achieved by increasing calcium levels in the media. These results exclude autonomous PTH secretion (non-calcium dependent) as a possible aetiology of acute primary hyperparathyroidism. We suggest that a sudden increase in the set-point of the diseased parathyroid cells in the presence of a huge cell mass accounts, in large part, for both the marked hypercalcaemia and elevated PTH levels in this patient.

Acute Disease↗

PubMed1991

The role of circulating N-terminal parathyroid hormone fragments in the early postparathyroid adenomectomy period.

Calcium metabolism and hormonal control after parathyroid adenomectomy are poorly understood. During the first postoperative hours, biologically active intact parathyroid hormone (PTH) (hPTH 1-84) levels are subnormal and, in spite of down-regulation of PTH peripheral receptors (caused by hypercalcemia before surgery), total and ionized calcium concentrations are maintained in the normal range. Serum samples from 20 patients with primary hyperparathyroidism were collected in the immediate preoperative period and 4 and 48 hours after excision of one parathyroid adenoma. Total and ionized calcium, intact (iPTH), midregion (mrPTH) specific PTH (hPTH 53-68), and N-terminal PTH (N-PTH) serum concentrations were determined. Levels of N-PTH were obtained with a radioimmunoassay by a modified reverse immunoextraction procedure that measures N-PTH fragments after exclusion of the interfering iPTH. No significant correlation was found between ionized and total calcium, mrPTH, and iPTH. However, total and ionized calcium levels correlated well with N-PTH (r = 0.9999, p = 0.0054, and r = 0.9993, and p = 0.0226, respectively). The data suggest that the relatively moderate decrease in calcium levels, in spite of marked decrease in circulating iPTH during the first postoperative hours, may be attributable to the minimal decrease of the bioactive N-PTH epitope concentrations. We would hypothesize that hPTH (1-34) fragments may play a significant role in regulating serum calcium levels in the early postoperative period.

Adenoma↗