Postoperative tetany in Graves disease: important role of vitamin D metabolites.
(1/1289)
OBJECTIVE: To test the authors' hypothesis of the causal mechanism(s) of postoperative tetany in patients with Graves disease. SUMMARY BACKGROUND DATA: Previous studies by the authors suggested that postoperative tetany in patients with Graves disease occurs during the period of bone restoration and resulted from continuation of a calcium flux into bone concomitant with transient hypoparathyroidism induced by surgery. PATIENTS AND METHODS: A prospective study was carried out to investigate sequential changes in serum levels of intact parathyroid hormone (iPTH), calcium and other electrolytes, 25-hydroxyvitamin D (25OHD), 1,25-dihydroxyvitamin D (1,25(OH)2D), and bone metabolic markers in 109 consecutive patients with Graves disease who underwent subtotal thyroidectomy. RESULTS: Preoperative serum iPTH levels negatively correlated with ionized calcium levels and positively correlated with 1,25(OH)2D or 1,25(OH)2D/25OHD. After the operation, there was a significant decline in levels of ionized calcium, magnesium, and iPTH. Serum iPTH was not detected in 15 patients after surgery. Four of these 15 patients, and 1 patient whose iPTH level was below normal, developed tetany. Preoperative serum ionized calcium levels were significantly lower, and iPTH levels were higher, in the 5 patients with tetany than in the 11 patients who did not develop tetany despite undetectable iPTH levels. The tetany group had significantly lower serum 25OHD levels and higher 1,25(OH)2D levels, and had increased 1,25(OH)2D/25OHD as an index of the renal 25OHD-1-hydroxylase activity than those in the nontetany group. These results suggest that patients with a high serum level of iPTH as a result of low serum calcium levels (secondary hyperparathyroidism) are susceptible to tetany under conditions of hypoparathyroid function after surgery. CONCLUSIONS: Postoperative tetany occurs in patients with secondary hyperparathyroidism caused by a relative deficiency in calcium and vitamin D because of their increased demand for bone restoration after preoperative medical therapy concomitant with transient hypoparathyroidism after surgery. Calcium and vitamin D supplements may be recommended before and/or after surgery for patients in whom postoperative tetany is expected to develop. (+info)
A new rapid technique for the fixation of thyroid gland surgical specimens.
(2/1289)
One of the main diagnostic problems in thyroid pathology is to distinguish between follicular adenoma and follicular carcinoma. Thorough sampling of the nodule's capsule is recommended in order to identify capsular invasion. However, during the hardening of the tissue, by the usual fixatives the capsule shrinks and rolls downwards and sometimes the capsule separates from the remaining tissue. The present work evaluates the use of "Lymph Node Revealing Solution" (LNRS) for the rapid fixation (2h) of different thyroid lesions as compared to that of formalin. Fifty-one unselected consecutive cases of thyroid nodules, which included various benign and malignant lesions, were examined. Each specimen was cut in two equal parts; one was fixed in LNRS, the other in formalin. Fixation in LNRS for 2 hours gave adequate results in sectioning and staining of the tissue, and excellent immunostains. Its advantage over formalin is the conservation of the natural relationship between the capsule and the rest of the tissue, on the same plane, as well as the short time required for the final diagnosis. (+info)
Large goitre causing difficult intubation and failure to intubate using the intubating laryngeal mask airway: lessons for next time.
(3/1289)
A 63-yr-old woman was anaesthetized for sub-total thyroidectomy. The thyroid gland was large, deviating the trachea to the right and causing 30% tracheal narrowing at the level of the suprasternal notch. Mask ventilation was easy but laryngoscopy was Cormack and Lehane grade 3. Despite being able to see the tip of the epiglottis, tracheal intubation was impossible. An intubating laryngeal mask was inserted and although the airway was clear and ventilation easy, it was not possible to intubate the trachea either blindly or with the fibreoptic bronchoscope. Tracheal intubation was eventually achieved using a 6.5-mm cuffed oral tracheal tube via a size 4 laryngeal mask under fibreoptic control. We describe the case in detail and discuss the use of the intubating laryngeal mask, its potential limitations and how to optimize its use in similar circumstances. (+info)
Multiple endocrine neoplasia type 2A with the identical somatic mutation in medullary thyroid carcinoma and pheochromocytoma without germline mutation at the corresponding site in the RET proto-oncogene.
(4/1289)
A germline mutation either in exon 10 or 11 of the RET proto-oncogene is found in the majority of patients with multiple endocrine neoplasia type 2A (MEN 2A). A 41-year-old female patient was referred for further evaluation of incidentally discovered right adrenal tumor. She had bilateral adrenal pheochromocytomas and medullary thyroid carcinomas detected by endocrinological and radiological examination, and diagnosed as MEN 2A. Molecular genetic testing of the RET exons 10 and 11 exhibited the identical somatic missense mutation at codon 634 in both tumors but did not confirm germline mutations in the corresponding sites. Possible mechanisms for tumorigenesis in this patient are discussed. (+info)
Management of differentiated thyroid cancer diagnosed during pregnancy.
(5/1289)
OBJECTIVE: To assess the outcome of thyroid cancer diagnosed during pregnancy. DESIGN: Retrospective analysis of patients diagnosed between 1949 and 1997 with thyroid cancer presenting during pregnancy. RESULTS: Nine women with a median age of 28 years were identified. A thyroid nodule was discovered by the clinician during routine antenatal examination in four cases, the remainder had noted a lump in the neck. In all patients, the nodule was reported to almost double in size during the pregnancy. One patient underwent subtotal thyroidectomy during the second trimester; eight were operated on within 3 to 10 months from delivery. Total thyroidectomy was performed in five and subtotal thyroidectomy in four. All tumours were well differentiated and ranged in size from 1 to 6 cm. OUTCOME: The median follow-up was 14 years (5-31 years). One patient relapsed locally requiring further surgery. One patient developed bone metastases dying 7 years after presentation; her planned treatment had been delayed because of an intervening pregnancy. Eight of the original cohort of patients are currently disease free. CONCLUSIONS: Differentiated thyroid cancer presenting in pregnancy generally has an excellent prognosis. When the disease is discovered early in pregnancy, surgery should be considered in the second trimester but radioiodine scans and treatment can be safely delayed until after delivery. In all cases, treatment should not be delayed for more than a year. (+info)
Thyroid hormone suppresses hepatic sterol 12alpha-hydroxylase (CYP8B1) activity and messenger ribonucleic acid in rat liver: failure to define known thyroid hormone response elements in the gene.
(6/1289)
Sterol 12alpha-hydroxylase (CYP 8B1) is a microsomal cytochrome P450 enzyme involved in bile acid synthesis that is of critical importance for the composition of bile acids formed in the liver. Thyroidectomy of rats caused a more than twofold increase of CYP8B1 and an almost fourfold increase of the corresponding mRNA levels compared to sham-operated rats. Treatment of intact rats with thyroxine caused a 60% reduction of enzyme activity and a 50% reduction of mRNA levels compared to rats injected with saline only. To investigate whether the promoter of the gene contains thyroid hormone response elements, the complete structure of the rat gene was defined. In similarity with the corresponding gene in mouse, rabbit and man, the rat gene was found to lack introns. It had an open reading frame containing 1500 bp corresponding to a protein of 499 amino acid residues. Although thyroid hormone decreased CYP8B1 activity and mRNA in vivo, no hitherto described thyroid hormone response elements were identified 1883 bases upstream of the transcription start site. It is concluded that rat CYP8B1 is regulated by thyroid hormone at the mRNA level. The results are discussed in relation to the structure of the gene coding for the enzyme. (+info)
Intestinal ganglioneuromatosis and multiple endocrine neoplasia type 2B: implications for treatment.
(7/1289)
Three infants, who presented with intestinal obstruction due to diffuse transmural intestinal ganglioneuromatosis, are described. Mutation analysis of exon 16 of the RET proto-oncogene revealed germline M918T and thus, a molecular diagnosis of multiple endocrine neoplasia type 2B (MEN 2B). Two infants developed medullary carcinoma of the thyroid. The third had a prophylactic thyroidectomy despite no obvious thyroid masses and normal calcitonin concentrations, but microscopic multifocal medullary carcinoma was found on histological examination. Early recognition of intestinal ganglioneuromatosis with germline RET M918T mutation in pseudo-Hirschsprung's disease is an indication for prophylactic thyroidectomy. (+info)
Calcitonin is a major regulator for the expression of renal 25-hydroxyvitamin D3-1alpha-hydroxylase gene in normocalcemic rats.
(8/1289)
Regulation of vitamin D metabolism has long been examined by using vitamin D-deficient hypocalcemic animals. We previously reported that, in a rat model of chronic hyperparathyroidism, expression of 25-hydroxyvitamin D3-1alpha-hydroxylase (CYP27B1) mRNA was markedly increased in renal proximal convoluted tubules. It is believed that the major regulator for the expression of renal CYP27B1 is parathyroid hormone (PTH). However, in the normocalcemic state, the mechanism to regulate the renal CYP27B1 gene could be different, since plasma levels of PTH are very low. In the present study, the effect of PTH and calcitonin (CT) on the expression of renal CYP27B1 mRNA was investigated in normocalcemic sham-operated rats and normocalcemic thyroparathyroidectomized (TPTX) rats generated by either PTH or CaCl2 infusion. A single injection of CT dose-dependently decreased the expression of vitamin D receptor mRNA in the kidney of normocalcemic sham-TPTX rats. Concomitantly, CT greatly increased the expression of CYP27B1 mRNA in the kidney of normocalcemic sham-TPTX rats. CT also increased the expression of CYP27B1 mRNA in the kidney of normocalcemic TPTX rats. Conversion of serum [3H]1alpha,25(OH)2D3 from 25-hydroxy[3H]vitamin D3 in vivo was also greatly increased by the injection of CT into sham-TPTX rats and normocalcemic TPTX rats, but not into hypocalcemic TPTX rats. In contrast, administration of PTH did not induce the expression of CYP27B1 mRNA in the kidney of vitamin D-replete sham-TPTX rats and hypocalcemic TPTX rats. PTH increased the expression of renal CYP27B1 mRNA only in vitamin D-deficient hypocalcemic TPTX rats. These results suggest that CT plays an important role in the maintenance of serum 1alpha,25(OH)2D3 under normocalcemic physiological conditions, at least in rats. (+info)