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PubMed2000

Paradoxical vocal cord motion causing stridor after thyroidectomy.

Two women developed stridor immediately after thyroidectomy as a result of paradoxical vocal cord motion. In both cases the cord function showed a normal pattern during vocalisation but paradoxical movement was seen at laryngoscopy during tidal breathing. The abnormality improved in both patients over time with speech therapy. Whilst the syndrome of paradoxical vocal cord motion is classically thought to have a largely psychological aetiology, subtle interference with laryngeal innervation at surgery is more likely to have been the cause in these cases.

Adult↗
PubMed1981

Protein synthesis in perfused rat liver following thyroidectomy and hormone treatment.

Rat livers perfused in situ were used to investigate the effects of thyroid hormone deficiency and subsequent hormone replacement on hepatic protein synthesis and secretion. Following surgical thyroidectomy, production of albumin and total secretory proteins was reduced by 50%, whereas the synthesis of retained intracellular proteins was reduced by only 20% compared to the respective control rates. The 28% reduction in the synthesis of total liver proteins (secreted plus retained) was associated with a fall of similar magnitude in the tissue RNA level. Treatment of thyroidectomized rats with various doses of thyroid hormones indicated a regimen that restored the rate of synthesis of total liver proteins and the concentration of RNA to normal levels. This treatment regimen increased the synthesis of retained proteins to 115% of the control rate, but produced only modest increases in the production of albumin and total secretory proteins. These findings indicated an impairment in protein secretion in livers of thyroidectomized rats that persisted after the defect in protein synthesis was corrected by thyroid hormone treatment.

Animals↗
PubMed1998

Blockage of gonadotropin-induced first ovulation caused by thyroidectomy and its possible mechanisms in rats.

To determine the role of the thyroid gland on the ovarian functions during the initiation process of puberty, we examined the effects and its mechanisms of hypothyroidism on the first ovulation induced by equine chorionic gonadotropin (eCG) in immature female rats. Animals were thyroidectomized on day 22 and were injected with 5 IU of eCG on day 26 to induce the first ovulation on day 29. The number of antral follicles that secrete inhibin and the ovarian weight were significantly increased in thyroidectomized rats (Tx rats) 48 h after eCG treatment compared with those in non-Tx rats. However, thyroidectomy (Tx) significantly suppressed the rates of ovulating animals on day 29. The blockage of ovulation in Tx rats was recovered by administration of human chorionic gonadotropin or luteinizing hormone (LH)-releasing hormone (LHRH) on day 28. Inhibition of serum LH (not follicle-stimulating hormone) levels induced by Tx was almost restored to control levels by injection of LHRH. A significant increment in prolactin levels in Tx rats was also observed on day 28. The present data indicate that Tx before puberty in female rats causes the blockage of the first ovulation and that the inhibitory effects on ovulation are mainly due to the reduction in the preovulatory LH surge, which is partially mediated through an inhibition of LHRH action on the secretion of LH.

Animals↗
PubMed1989

Gastric acid secretion and parietal cell mass: effects of thyroidectomy and thyroxine.

The role of thyroid hormones on parietal cell function and number was studied in the rat. Chronic administration of thyroxine (6-8 micrograms/100 g body wt/day) for 35 days significantly increased parietal cell mass (from 21.18 +/- 0.13 x 10(6) to 26.71 +/- 0.14 x 10(6] as well as basal acid secretion (from 3.69 +/- 0.08 to 4.99 +/- 0.16 mueq/10 min) and histamine-stimulated acid secretion (from 2.45 +/- 0.12 to 3.69 +/- 0.21 mueq/10 min). Thyroidectomy decreased the number of parietal cells in the gastric mucosa (to 10.48 +/- 0.09 x 10(6] and basal acid secretion (to 3.09 +/- 0.08 mueq/10 min). Histamine (0.2 mg) injection into the thyroidectomized rats increased acid secretion by only 1.41 +/- 0.06 mueq/10 min as against 2.45 +/- 0.12 mueq/10 min obtained for control rats. The results suggest that thyroid hormones regulate basal and secretagogue-stimulated acid secretion via their effects on parietal cell mass.

Animals↗
PubMed1986

Antihypertensive effect of thyroidectomy in SHR: associated changes in heart performance.

Effects of thyroidectomy (TX; 10 wk) on the performance of perfused hearts from spontaneously hypertensive rats (SHR) were compared with effects on hearts from normotensive Wistar-Kyoto (WKY) controls. TX prevented the development of hypertension in SHR and moderately reduced arterial pressure of WKY, confirming previous observations. TX also reduced heart-to-body-weight ratio (relative left ventricular hypertrophy) but not left-to-right ventricular weight ratio (absolute hypertrophy) of SHR. The performances of euthyroid SHR and WKY hearts were similar to each other. TX reduced maximum left ventricular pulse pressure to the same extent in both strains and had no effect on hydraulic work, O2 consumption, or efficiency of contraction in either strain. However, TX reduced maximum left ventricular +dP/dt of SHR but not of WKY hearts. The results show that hypothyroidism selectively depresses the contractility (LV +dP/dt) of SHR hearts but otherwise has similar effects on the performance of hypertensive and normotensive rat hearts.

Age Factors↗
PubMed1991

Effects of thyroidectomy on development of skeletal muscle in fetal sheep.

The influence of the thyroid gland on the functional and histochemical development of fast- and slow-twitch skeletal muscle of fetal sheep has been studied in euthyroid fetal sheep (n = 6) and athyroid fetuses (n = 4) surgically thyroid-ectomized at 70-75 days of gestation. Two fast-twitch muscles, the medial gastrocnemius and extensor digitorum longus, and the slow-twitch soleus muscle were studied at the fetal age of 140 days gestation. The athyroid fetuses had significantly slower twitch contraction and relaxation times in both the medial gastrocnemius and extensor digitorum longus muscles compared with the euthyroid fetuses. Twitch contraction and relaxation times of the soleus were not different in the two groups. Thyroidectomy resulted in an increase in the proportion of fast (type II) muscle fibers and myosin, as shown histochemically and by gel electrophoresis of heavy-chain myosins. These results indicate that the functional maturation of the fast-twitch muscles of sheep is influenced by the presence of an intact thyroid gland from at least 70 days of gestation. In contrast, the slow-twitch soleus muscle fiber diameter and twitch contraction and relaxation times were not different in the two groups.

Animals↗
PubMed1998

Impaired water excretion in a hyponatremic patient following thyroidectomy: causal role of glucocorticoid deficiency.

We evaluated the causal role of glucocorticoid deficiency in the hyponatremia that developed in a 57-year-old Japanese man with hypothyroidism following the performance of a total thyroidectomy for laryngeal cancer. The plasma concentration of vasopressin (1.78 pg/ml) was not suppressed in the presence of hyponatremia (125 mEq/l). The urinary excretion of sodium was increased, and the plasma renin activity and plasma aldosterone concentration were suppressed. The infusion of hypertonic saline increased the plasma osmolality, but not the plasma concentration of vasopressin. An oral water load (20 ml/kg of body weight) did not suppress the plasma vasopressin level or induce diuresis. Pretreatment with hydrocortisone normalized the response of plasma vasopressin to the water load was well as the diuretic response during the hypothyroid state. The urinary excretion of 17-hydroxycorticosteroids was below normal in the hypothyroid state in the face of normal serum cortisol concentration. The correction of the hypothyroidism returned these abnormalities to normal. A disturbed metabolism of glucocorticoid may have been responsible for the hyponatremia and disturbance in plasma vasopressin regulation observed in this hypothyroid patient.

Diuresis↗
PubMed1985

Distribution and release of immunoreactive thyroid-stimulating hormone in the rat hypothalamus: effects of thyroidectomy, hypophysectomy and treatment with thyroid hormones.

Immunoreactive thyroid-stimulating hormone (IR-TSH) has been detected in the hypothalamus and is released in vitro by a calcium-dependent mechanism when the tissue is depolarized. Recently, immunocytochemical studies have revealed that IR-TSH is present in thyrotropes in the pars tuberalis. Therefore, because these thyrotropes are associated with the median eminence, the area with the highest concentration of IR-TSH, it is of interest to determine if 'hypothalamic' IR-TSH is from neural or pituitary cells. We addressed this issue by studying the effects of hypophysectomy, thyroidectomy, or chronic administration of triiodothyronine (T3) or thyroxine (T4) on the distribution and in vitro release of IR-TSH in the hypothalamus. We reasoned that, if hypothalamic IR-TSH is dependent on the thyrotropes of the pars tuberalis, then changes in hypothalamic IR-TSH concentration and release should be parallel to those measured in pituitary extracts. IR-TSH was measured in tissue extracted in ice-cold 2% NaCl, with a final pH of 4.5. For the in vitro studies, tissues were incubated for 20-min periods in Krebs-Ringer bicarbonate buffer at 37 degrees C. In untreated rats, the concentration of IR-TSH is greater in the ventral than the dorsal portion of the hypothalamus (39.3 +/- 8.2 vs. 4.0 +/- 1.5 ng/mg wet wt.). Upon finer dissection of the hypothalamus into median eminence and anterior, middle, and posterior portions of the remainder, IR-TSH was only detectable in the middle hypothalamus (5.3 +/- 1.5 ng/mg), and the median eminence (149 +/- 41 ng/mg).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

An appropriate model for congenital hypothyroidism in the rat induced by neonatal treatment with propylthiouracil and surgical thyroidectomy: studies on learning ability and biochemical parameters.

Hypothyroidism was induced in rats by treatment with propylthiouracil through the mother's milk throughout the suckling period followed by surgical thyroidectomy without use of radioiodine. The growth of these animals was considerably retarded and their light-dark discriminative operant learning ability was also significantly decreased. Replacement therapy with thyroxine to maintain its normal serum concentration was effective for continuing normal growth and development of learning ability. Therefore, these hypothyroid rats are a useful model of congenital hypothyroidism. Biochemical studies showed that the inhibition of cerebral Na,K-ATPase and succinic dehydrogenase activities detected in early postnatal life in these hypothyroid rats was transient and that normal activities of these enzymes were later regained in adult rats. However, the activity of 2',3'-cyclic nucleotide 3'-phosphohydrolase and the brain myelin remained low throughout life unless thyroxine was administered. Though a critical correlation between biochemical parameters and learning ability is still uncertain, these results suggest that the formation of myelin in the neonatal period is at least dependent on thyroid hormone and would play an important role in mental development.

Animals↗
PubMed1989

Mass and in situ molar activity of tyrosine hydroxylase in the median eminence. Effect of thyroidectomy and thyroid hormone replacement.

The effects of thyroidectomy and thyroid hormone replacement on the mass and in situ molar activity of tyrosine hydroxylase (TH) in the median eminence (ME) and superior cervical ganglia (SCG) of male rats were investigated. The tissue specificity of these effects were evaluated by comparing the ME with the superior cervical ganglion (SCG). All animals were thyroparathyroidectomized (Tx) or sham Tx. Tx rats were treated daily for 3 weeks with 0.15 M NaCl (solvent vehicle) or L-thyroxine (T4). Two doses of T4, 10 and 100 micrograms/day/kg BW, were used. Sham Tx rats were treated with 0.15 M NaCl. All animals were studied on the day following the last treatment. The mass of TH was determined using an immunoblot assay, and the in situ activity of TH was calculated from the rate of intracellular accumulation of L-dihydroxyphenylalanine (DOPA) after administration of an inhibitor of DOPA decarboxylase activity. In the ME, thyro-parathyroidectomy resulted in a 40% increase in the mass and a 100% increase in the in situ molar activity of TH over that of sham Tx rats. Compared to Tx animals given 0.15 M NaCl, Tx rats treated with a low dose of T4 (10 micrograms/day/kg BW) had a reduced quantity of TH in the ME, but the molar activity of the enzyme was increased. Treatment of Tx rats with a high dose of T4 (100 micrograms/day/kg BW) restored TH mass but not the in situ activity of TH in the ME to the level seen in sham Tx rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1977

Effects of thyroidectomy and thyroxine on plasma growth hormone and insulin levels in rats.

Plasma growth hormone and insulin levels were measured in normal, thyroidectomized (TX), and TX rats treated with 1-thyroxine (1-T4) or rat-growth hormone (r-GH). Although normal growth was observed 5 days after surgery, a decrease of circulating levels of GH was evidenced as early as 5 days after the operation. However, the plasma insulin levels were not affected by the 5th, 10th and 15th day of thyroidectomy. With a more prolonged thyroid hormone deprivation, the plasma insulin levels of TX rats remained lower than those of age-paired controls. Treatment of hypothyroid rats with 0.05 micron 1-T4 for 10 days induced growth and an increase in circulating GH levels, but had no effect on the low levels of plasma insulin of TX rats. Treatment of TX animals with 0.10 or 0.20 micron 1-T4, or 100 micron r-GH during 10 days caused plasma insulin levels to shift toward the values of their weight-paired controls. However, treatment of hypophysectomized (HX) rats with 0.20 micron T4 during 8 days did not change the circulating levels of plasma insulin. It is suggested that thyroid hormone deprivation results in a decrease of circulating levels of insulin secondary to a deficiency in growth hormone secretion. In addition, normal GH secretion appears to be required for normal pancreatic insulin secretion to occur.

Animals↗
PubMed1993

Successful outcome of pregnancy complicated with thyroidectomy-induced hypoparathyroidism and sudden dyspnea. A case report.

Total thyroidectomy is often accompanied with airway problem and hypoparathyroidism leading to infertility and pregnancy losses, and its effects are thus rarely reported on delivery. A patient with postoperative hypoparathyroidism carried a pregnancy to successful delivery, but suffered uncontrollable hypocalcemia and sudden respiratory distress at spontaneous labor onset. Both the fetal and maternal outcome were good. The acute deterioration in the hypoparathyroidism and airway problem at labor differed from the complications in previously reported cases.

Adenocarcinoma, Papillary↗
PubMed1981

Hydrolase activities in the rat aorta. V. Comparison to activities in liver and kidney after thyroidectomy and relation to dynamic clearance of circulating low density lipoproteins.

Thyroid hormones influence circulating low density lipoprotein (LDL) levels in humans; they could have an effect on LDL catabolism. Male rats were thyroidectomized (H); half were treated for 7 days with 2 micrograms triiodothyronine/100 g body weight (T) and both groups were compared to controls (C). Aorta, liver, and kidney were assayed for cellular marker enzymes, including lysosomal acid cholesteryl esterase (ACE). Specific activities of ACE (mU/mg DNA; mean +/- SD) were: Aorta, C, 0.19 +/- 0.01; H, 0.16 +/- 0.01; T, 0.21 +/- 0.01; Liver: C, 15.55 +/- 1.49; H, 9.16 +/- 1.54; T, 15.43 +/- 2.28; Kidney: C, 1.70 +/- 0.23; H, 1.04 +/- 0.13; T, 2.08 +/- 0.35. Half lives for injected unmodified 125I-labeled human LDL were 11.5 +/- 0.7 hour in C, 16.2 +/- 3.1 in H, and 12.9 +/- 0.9 in T groups. Fractional catabolic rates (FCR) of LDL in %/hr were 6.5 +/- 0.6 in C; 4.8 +/- 0.5 in H, and 6.0 +/- 0.3 in T. Reductively methylated 125I-labeled human LDL had half-lives of 14.9 +/0 1.4 hour in C and 15.1 +/- 1.6 hour in H and the FCR of this modified LDL was 5.3 +/- 0.5 %/hr in C and 5.2 +/- 0.7 %/hr in H groups. Thus, thyroidectomy results in marked decreases in ACE specific activity of liver and kidney and a marked decrease in FCR and prolonged half-life of non-modified LDL (all P less than 0.05). On the other hand, methylated LDL showed a similarly reduced FCR and prolonged half-life in control and thyroidectomized rats (P less than 0.05). This suggests a major effect of thyroid deficiency on receptor-mediated uptake of LDL in vivo and demonstrates the influence of hormonal status on dynamic clearance and catabolism of LDL.

Animals↗
PubMed1998

Thirty-eight-year evaluation of a surgical technique to protect the external branch of the superior laryngeal nerve during thyroidectomy.

The purpose of this study is to evaluate a surgical technique for the preservation of the function of the external branch of the superior laryngeal nerve (EBSLN) during total thyroid lobectomy and total thyroidectomy. Permanent injury to this nerve can be a disaster, especially in singers and professional speakers who depend on control of pitch, and a clear and forceful voice. Voice changes may be either obvious or subtle. For better voice analysis, a detailed questionnaire is necessary. Thus, the evaluation in this study is based on laryngoscopy of 934 nerves in 675 patients and detailed subjective voice evaluation of 66 patients during the last 2 years of the study. There are 2 surgical principles. First, the EBSLN is not routinely exposed; the distal 1.5 to 2.0 cm (critical area) of the superior thyroid vessels are carefully dissected, exposed, and ligated, preferably independently. Careful observation ensures that the EBSLN is not included in the ligature. Second, the ultimate evaluation of the surgical technique is the effect of voice changes on the patient's lifestyle. Laryngoscopy of 934 nerves found bowing, temporary in 4 patients and permanent in 1 patient (limited follow-up). Of the 66 patients with voice evaluations, 14 had changes: 9 had temporary changes, while 5 had permanent changes. In these 14 patients, voice changes had no effect on lifestyle in 13, and the effects were indeterminate in 1 (unavailable for follow-up). The estimated deleterious effect of voice changes on lifestyle is no greater than 1.5% of the 66 patient responders.

Anatomy, Artistic↗
PubMed1995

Unrecognized hypocalcaemia diagnosed 36 years after thyroidectomy.

Hypoparathyroidism can present many years after thyroidectomy and symptoms may be non-specific. Hypocalcaemia may cause a variety of physical and mental symptoms and the diagnosis is easily overlooked with serious and potentially fatal consequences. Patients with vague symptoms should always be asked about previous thyroid surgery and serum calcium should be measured.

Chronic Disease↗
PubMed1989

Complications after total thyroidectomy.

A retrospective review of 64 total thyroidectomies performed at Memorial Sloan-Kettering Cancer Center was conducted. Only one patient had permanent hypocalcemia (1.6%) requiring calcium supplementation. Eight patients had a total of 11 complications, for a complication rate of 12.5%. These results are in sharp contrast to those published in 1972 from this institution, in which the permanent hypocalcemia rate was 29%. The reasons for this difference are discussed.

Adenocarcinoma↗
PubMedDate not supplied

Prophylactic thyroidectomy in MEN 2A syndrome.

Genetic testing is the appropriate procedure in MEN 2A syndrome for the early diagnosis of medullary carcinoma even at a preclinical stage. Prophylactic total thyroidectomy represents the standard preventive and therapeutic surgical approach in the treatment of medullary thyroid carcinoma in MEN 2A syndrome. Our experience has confirmed the presence of CCH and medullary thyroid carcinoma even in clinically negative patients, in agreement with reports in the literature.

Adult↗
PubMed1998

Propofol maintenance to reduce postoperative emesis in thyroidectomy patients: a group sequential comparison with isoflurane/nitrous oxide.

The clinical benefit of propofol anaesthesia in the prevention of postoperative nausea and vomiting (PONV) is still being elucidated despite many studies to date. In this study 64 adult female patients scheduled for thyroidectomy received, in a randomized double-blind fashion, propofol with air or isoflurane with nitrous oxide for maintenance of anaesthesia. The primary response variable was the presence or absence of vomiting in the first six hours. A group sequential design was used to allow interim analysis. After 64 patients, the fourth analysis showed that fewer patients receiving propofol vomited or required an anti-emetic during the first six hours (P < 0.05). There was no significant difference detected in the 6 to 24 hour interval. In this group of female patients, total intravenous anaesthesia (TIVA) with propofol is associated with an early reduction in early postoperative vomiting compared with standard inhalational techniques. This reduction in vomiting does not appear to persist beyond the first six hours.

Adult↗