Influence of extradural blockade on serum thyroid hormone concentrations after surgery

To study the changes in thyroid hormone metabolism after surgery, the influence of neurogenic blockade by extradural local anaesthetics, and possible hormonal interactions, 16 women undergoing cholecystectomy were randomly allocated to two groups of eight each. All patients received general anaesthesia and in addition one group received extradural blockade for 24 h. Preoperatively and at 2, 4, 6, 12 and 24 h after skin incision arterial serum concentrations of thyroid hormones (T3, free T3, rT3, T4, free T4 and TSH), catecholamines (adrenaline and noradrenaline), cortisol and serum proteins (albumin, prealbumin and TBG) were determined. In both groups total T3, free T3, total T4 and TSH decreased significantly whereas free T4 was unchanged and rT3 increased. No differences between the extradural group and the controls regarding thyroid hormones were observed, in spite of suppressed catecholamine and cortisol concentrations in the extradural group as compared to the control group. All serum thyroid hormone binding proteins decreased significantly in both groups. Changes in thyroid hormone metabolism after surgery seem independent of neurogenic blockade by extradural local anaesthetics, and of plasma catecholamine and cortisol concentrations.     

连续星状神经节阻滞对重度颅脑损伤患者血清甲状腺激素及皮质醇水平的影响

目的 探讨连续星状神经节阻滞对重度颅脑损伤患者血清甲状腺激素[三碘甲状腺原氨酸(T3)、甲状腺素(T4)、反三碘甲状腺原氨酸(rT3)、促甲状腺激素(TSH)]及皮质醇(Cor)水平的影响.方法 急诊行开颅手术的重度颅脑损伤患者80例,性别不限,年龄22～61岁,ASA分级Ⅱ或Ⅲ级,格拉斯哥昏迷量表评分3～8分,采用随机数字表法,将患者随机分为2组(n=40):对照组(C组)和连续星状神经节阻滞组(SGB组).气管插管后SGB组于开颅侧行连续SGB,注射0.2%罗哌卡因7ml后,持续输注0.2%罗哌卡因2 ml/h,持续时间为48 h;2组术后均予常规治疗.于术前30 min、术后3、7 d采集静脉血样,采用放射免疫法测定血清T3、T4、rT3、TSH及Cor浓度;术后90 d采用格拉斯哥预后评分判定临床疗效.结果 与C组比较,SGB组术后血清T3浓度升高,T4、rT3、TSH和Cor浓度降低(P＜0.05或0.01),SGB组临床疗效分级优于C组(P＜0.05).结论 连续星状神经节阻滞可有效减轻重型颅脑损伤患者的应激反应,改善下丘脑-垂体-甲状腺轴功能,有助于患者恢复.

Abstract：

Objective To investigate the effects of continuous stellate ganglion block (SGB) on serum thyroid hormone and cortisol levels in patients with severe brain injury.Methods Eighty ASA Ⅱ or Ⅲ patients with severe brain injury aged 22-61 yr undergoing emergency craniotomy were randomly divided into 2 groups ( n = 40 each): control group (group C) received routine treatment only and continuous SGB group (group SGB) received continuous SGB with 0.2% ropivacaine besides routine treatment. SGB was performed on the operated side after induction of general anesthesia and tracheal intubation. An epidural catheter was placed. A bolus of 0.2% ropivacaine 7 ml was followed by continuous infusion of 0.2% ropivacaine at a rate of 2 ml/h. Continuous SGB was maintained for 48 h. Successful SGB was confirmed by increase in skin temperature by ≥1.5℃ behind earlobe on the operated side.Venous blood samples were obtained at 30 min before and 3 and 7 day after operation for determination of serum thyroid stimulating hormone (TSH), triiodothyronine (T3) ,thyroxine (T4) , reverse triiodothyronine(rT3) and cortisol concentrations. Glasgow prognosis score was used to evaluate the clinical results at 3 months after operation. Results Serum T4 , rT3 , TSH and cortisol concentrations were significantly lower while the serum T3 concentration was higher in the SGB group than in group C at 3 and 7 d after operation. The clinical results were significant better in SGB group than in group C according to Glasgow prognosis scores at 3 months after operation. Conclusion Continuous SGB can inhibit the stress response, and improve hypothalamus-pituitary-thyroid gland axis function and is helpful to patient's recovery from injury.     

Thyroid hormone changes after cardiovascular surgery and clinical implications

Alterations in serum concentrations of total triiodothyronine (TT3), total thyroxine (TT4), and thyroid-stimulating hormone (TSH) frequently occur in patients with nonthyroidal illnesses. These changes correlate with the severity of the illness and the prognosis. In this study, 44 patients undergoing a cardiovascular operation had significant declines in serum TT3 and TT4 levels during cardiopulmonary bypass and thereafter. Serum TT3 and TT4 concentrations reached their nadir at 30 minutes after the start of cardiopulmonary bypass with values (mean +/- standard error of the mean) of 0.77 +/- 0.12 nmol/L (50.4 +/- 7.6 ng/dL) and 68.2 +/- 10.2 nmol/L (5.30 +/- 0.79 micrograms/dL), respectively. The mean serum concentrations of TSH and TT4 returned to preoperative levels by the sixth day after operation, whereas TT3 levels remained low throughout the study period. The patients whose recovery was uneventful had higher serum TT3, TT4, and TSH levels than those who had complications or died. The trend toward recovery was initiated by a sharp increase in the serum TSH level and increases in serum TT3 and TT4 concentrations on the fourth day after operation. Patients with complications either did not show these changes or had only a transient increase in TT3 and TT4 levels. All of the patients had a normal serum free T4 level before anesthesia. Those with an uneventful recovery had a higher serum free T4 level on the sixth day after operation than those with complications. Two patients in the latter group had serum free T4 levels less than normal at that time.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of Thyroid Function in Obese Dogs and in Dogs Undergoing a Weight Loss Protocol

Summary Obesity and weight loss have been shown to alter thyroid hormone homeostasis in humans. In dogs, obesity is the most common nutritional problem encountered and weight loss is the cornerstone of its treatment. Therefore, it is important to clarify how obesity and weight loss can affect thyroid function test results in that species. The objectives of this study were to compare thyroid function in obese dogs and in lean dogs and to explore the effects of caloric restriction and weight loss on thyroid hormone serum concentrations in obese dogs. In the first experiment, 12 healthy lean beagles and 12 obese beagles were compared. Thyroid function was evaluated by measuring serum concentrations of total thyroxine (TT4), free thyroxine (FT4), total triiodothyronine (TT3), thyrotropin (TSH), and reverse triiodothyronine (rT3) as well as a TSH stimulation test using 75 μg IV of recombinant human TSH. In the second experiment, eight obese beagles were fed an energy‐restricted diet [average 63% maintenance energy requirement (MER)] until optimal weight was obtained. Blood samples for determination of TT4, FT4, TT3, TSH and rT3, were taken at the start and then weekly during weight loss. Only TT3 and TT4 serum concentrations were significantly higher in obese dogs as compared to lean dogs. In the second experiment, weight loss resulted in a significant decrease in TT3 and TSH serum concentrations. Thus obesity and energy restriction significantly alter thyroid homeostasis in dogs, but the observed changes are unlikely to affect interpretation of thyroid function test results in clinics.     

Spontaneous pituitary-thyroid function after surgical treatment of nontoxic goitre. A controlled long-term study

The free thyroxine index (FT4I), triiodothyronine (T3) and thyroid stimulating hormone (TSH) in serum and the peak serum TSH (TRH test) were measured in 18 patients with nontoxic uninodular goitre and 32 patients with nontoxic multinodular goitre before and 3, 6, 12, 24 and 36 months after goitre resection. Thyroid hormone therapy was not given postoperatively. Resection of non-toxic goitre provoked a transient rise in TSH baseline level, with peak about one year after surgery. Three years after the resection the TSH baseline had returned to the preoperative level. The TSH changes were significantly more pronounced in the multinodular goitrous group, in which resection was bilateral, than in the uninodular goitrous group. The changes in serum FT4I and serum T3 were of moderate degree and most pronounced in the multinodular group. During long-term observation, serum FT4I increased slightly but significantly in both groups, but serum T3 showed significant reduction, albeit within reference range. The results of the study suggest that thyroid hormone therapy as a routine procedure after simple goitre resection lacks a tenable rational basis.     

Low free thyroxine concentrations and deficient nocturnal surge of thyroid-stimulating hormone in haemodialysed patients compared with undialysed patients.

BACKGROUND: There is little information on the differences in pituitary-thyroid function between undialysed and haemodialysed patients. METHODS: Serum concentrations of free thyroxine (T(4)) and free triiodothyronine (T(3)), measured by enhanced chemiluminescence immunoassay, and thyroid-stimulating hormone (TSH) were compared in undialysed (n=22) and haemodialysed patients (n=85). The response of the serum TSH concentration to exogenously administered thyrotropin-releasing hormone (TRH) and circadian variation in serum TSH were also studied in the two groups. RESULTS: Serum free T(4) concentration was significantly lower in haemodialysed than in undialysed patients (1.02+/-0.02 vs 1.33+/-0.06 ng/dl, P<0.0001). Serum concentrations of free T(3) and TSH were essentially the same for the two groups. The response of serum TSH concentration to TRH was basically the same. Serum TSH concentration in undialysed patients during the night and in the morning were 142.4+/-15.4% and 121.7+/-4.1% of that during the day, the differences being significantly different. A nocturnal surge of TSH was not observed in haemodialysed patients. CONCLUSIONS: Low serum free T(4) concentration and a deficient nocturnal surge of TSH were found in haemodialysed patients compared with undialysed patients. The deficient nocturnal surge of TSH may contribute to the lower serum free T(4) concentration in haemodialysed patients.     

Per- and postoperative changes in the concentration of serum thyreotropin under general anaesthesia, compared to general anaesthesia with epidural analgesia

In 18 patients scheduled for lower intraabdominal surgery (hysterectomy), changes in thyreotropin (TSH) thyroxine (T4), triiodothyronine (T3) binding of thyroid hormones to plasma proteins (T3-uptake) and glucose in serum were evaluated. In eight patients afferent neurogenic impulses from the surgical area were blocked (Th4-S5) with bupivacaine 0.5% infused continuously into the epidural space from the start of the operation until 6 h postoperatively. All patients received general anaesthesia with thiopentone, pethidine, pancuronium and nitrous-oxide plus oxygen. The patients receiving epidural analgesia had no increase in plasma-TSH, compared to the other group, which had a significant (P less than 0.05) increase peroperatively. The patients receiving epidural analgesia were pain-free and the normal stress-induced increase in plasma-glucose was abolished. Concerning T3 we found a significant decrease in both groups and a steady level of T4- and T3-uptake without significant fluctuations. Thus it can be concluded that the effects of surgical trauma on plasma-TSH concentration are markedly similar to the effects of other anterior pituitary hormones, i.e. HGH, prolactin and ACTH.     

手术对甲状腺机能亢进患者T_3、T_4、TGA、TMA、TSH及皮质醇的影响

对30例甲状腺机能亢进患者手术前后血清甲状腺激素(T_3、T_4)、促甲状腺激素(TSH)、甲状腺球蛋白抗体(TGA)、甲状腺微粒体抗体(TMA)及皮质醇进行测定。结果:行甲状腺大部切除术后患者血清T_3、T_4、TMA、TGA在短期内迅速下降,皮质醇则在原低下的水平上更趋下降,而TSH的变化不大。甲状腺大部切除术对非甲状腺机能亢进患者的上述指标影响不大。因此,此类激素和抗体的测定对判断手术效果及预防甲状腺机能亢进危象的发生具有一定的临床意义。     

Anterior and posterior pituitary function in brain-stem-dead donors. A possible role for hormonal replacement therapy

Blood samples were obtained, at the time of organ donation, from 31 consecutive brain-stem-dead (BSD) donors referred to one transplant coordinator during a 9-month period. Twenty-four cases (77%) had clinical diabetes insipidus (DI), which was poorly controlled with marked dehydration in a majority of cases (serum osmolality range 268-357; median 302 mOSM/kg). Serum triiodothyronine (T3) was subnormal in 25 (81%); all had normal or high serum reverse T3; and the serum free thyroxine (T4) index was subnormal in 9 (29%), and TSH was subnormal in 7 (23%). In no case were T4 and TSH both subnormal and results were typical of the sick euthyroid syndrome rather than TSH deficiency. Of 21 cases not receiving corticosteroids, 5 (24%) had a serum cortisol above 550 nmol/L (20 micrograms/dl), excluding ACTH deficiency, and only 1 had undetectable cortisol levels. Those with severe hypotension did not have significantly lower serum cortisol (mean 354 vs. 416; P greater than 0.5). Levels of prolactin, growth hormone, gonadotrophins, and gonadal steroids were variable, but only a minority were frankly deficient in these hormones. BSD donors frequently have DI, which is often managed poorly by nonspecialists and requires appropriate replacement therapy. In contrast most patients are not totally deficient in anterior pituitary hormones. Routine hormonal therapy with cortisol and T3 cannot, therefore, be justified on endocrinological grounds. Widespread introduction of such treatment should only follow controlled trials that clearly demonstrate clinically significant improvement in the transplanted organ function, without detriment to the donor.     

Lack of nocturnal serum thyrotropin (TSH) surge in patients with chronic renal failure undergoing regular maintenance hemofiltration: a case of central hypothyroidism

Thyrotropin (TSH) secretion was evaluated in a group of patients with chronic renal failure (CRF) undergoing regular maintenance hemofiltration and in normal controls. The study group included 68 patients (39 males and 29 females, age range 39-73 years, mean: 53 years). In all patients blood was drawn at 08:30-09:00 h; in 20 patients the nocturnal (24:00-02:00 h) serum TSH peak was also evaluated; 12 patients underwent stimulation test with synthetic TSH-releasing hormone (TRH). TSH was measured by an ultrasensitive immunoradiometric assay. CRF patients showed a significant decrease in serum total and free thyroxine and triiodothyronine concentrations, which in a substantial proportion of subjects were below the lower normal limit. Serum reverse triiodothyronine and thyroxine-binding globulin values did not differ in the two groups. Despite this trend of thyroid hormones to decrease, no patient had supranormal TSH values as in primary hypothyroidism. While the mean morning TSH concentrations of CRF patients did not differ from those of controls, the mean nocturnal values were significantly reduced in CRF (1.0 +/- 0.2 vs 3.2 +/- 0.4 mU/l, p less than 0.0005) and the nocturnal serum TSH surge was not observed in 18 of the 20 patients (90%) in whom it was evaluated. The mean serum TSH peak value after TSH-releasing hormone (TRH) administration was also reduced in CRF patients, and the TSH response to TRH was blunted in 3 out of 12 patients (25%). The results of this study demonstrate a major impairment of TSH secretion in CRF, which baseline TSH measurements in the morning and the evaluation of the TSH response to TRH may not reveal.(ABSTRACT TRUNCATED AT 250 WORDS)     

心内直视手术对甲状腺激素代谢的影响及其临床意义

为了解体外循环心脏直视手术对甲状腺激素代谢的影响并探讨其临床意义。作者选择２１例心脏直视手术病人，用放免法分别于术前、术中、术后２、２４小时测定其血浆Ｔ３、Ｔ４、游离Ｔ３（ＦＴ３）、游离Ｔ４（ＦＴ４）、反Ｔ３（ｒＴ３）及促甲状腺激素ＴＳＨ的含量。结果发现Ｔ４、ＦＴ４术中降低，术后２小时恢复正常（Ｐ＜０．０５）。Ｔ３、ＦＴ３呈下降趋势，术后２４小时降至最低（Ｐ＜０．０１）。ｒＴ３进行性升高。ＴＳＨ术中一过性升高。结论：甲状腺激素在ＣＰＢ时变化为术中低Ｔ３、Ｔ４综合征，术后为低Ｔ３综合征。提示ＣＰＢ后Ｔ３补充治疗有利于病人康复及某些术后难治性心功能不全的处理。     

Somatotropic and thyroid hormones in the acute phase of subarachnoid haemorrhage

Background

Somatotropic and thyroid hormones are probably important for the recovery after acute brain injury. Still, the dynamics of these hormones after spontaneous subarachnoid haemorrhage (SAH) is not well described. The purpose of this study was to investigate the relation between somatotropic and thyroid hormones and clinical factors after SAH.

Methods

Twenty patients with spontaneous SAH were included prospectively. Serum concentrations of TSH, fT4, T3, IGF-1 and GH were measured once a day for 7 days after SAH. Hormone patterns and serum concentrations were compared to the severity of SAH, neurological condition at admission, clinical course and outcome of the patients.

Results

During the first week after SAH, all patients showed increased GH and IGF-1 concentrations. In the whole group, concentrations of TSH increased, whereas T3 and fT4 decreased. There were no relations of serum concentrations of IGF-1 or GH to clinical condition at admission, clinical course or outcome of the patients. Half of the patients showed low T3 serum concentrations. A complicated course was associated with a deeper fall in TSH and T3 concentrations. There were negative correlations for mean concentrations of TSH and T3 versus WFNS grade and a positive correlation for T3 versus GOS after 6 months, indicating that low concentrations of TSH and T3 were connected to worse SAH grade and poor outcome.

Conclusions

All patients showed increased GH and IGF-1 concentrations irrespective of the grade of SAH or clinical course. Patients with a complicated clinical course showed a more pronounced fall in TSH and T3 concentrations and low serum T3 concentrations were related to a more serious SAH and poor patient outcome. These results need to be studied further and they may contribute to the accumulated knowledge needed to understand the complex mechanisms influencing the unpredictable clinical course after SAH.     

Thyroid response to dexamethasone: A study on normal controls and patients with psychogenic sexual dysfunction: Der Einfluß von Dexamethason auf die Schilddrüsenfunktion bei Patienten mit erektiler Dysfunktion und gesunden Männern

Pre- and postdexamethasone triiodothyronine (T3), thyroxine (T4), and TSH levels of thirteen patients with psychogenic sexual dysfunction and thirteen controls were studied. Patients showed lowered T4 levels in comparison with the control group whereas T3 and TSH levels did not differ significantly. Dexamethasone had a suppressive effect on TSH in patients and in controls while T3 levels were suppressed in the control group only. Patients scored significantly higher on the Hamilton Depression Scale than controls. These results compared with results obtained in patients recovered from major depression might point to endocrinological as well as clinical interrelations between psychogenic sexual dysfunction and minor depression.     

Low triiodothyronine serum levels as a predictor of poor prognosis in burn patients

OBJECTIVE: Euthyroid sick syndrome is a common finding in critically ill patients with nonthyroidal illness, characterized by low serum levels of free triiodothyronine (fT3) with a peculiar increase in reverse T3 (rT3) and normal-to-low free thyroxine (fT4) as well as thyroid-stimulating hormone (TSH) levels. This condition has been proposed as a prognostic factor of worse outcome in critically ill patients, while no conclusive data are available in burns. METHODS: Since thyroid function testing is contained in our baseline laboratory tests at admission, we retrospectively evaluated fT3, fT4 and TSH in 295 consecutive burn patients admitted to the Burn Center of Turin from January 2002 to December 2006, comparing hormone levels in survivors and non-survivors. RESULTS: fT3 and TSH levels were significantly lower (p相似文献   

Thyroid hormone alterations in patients with shock and injury

Serum concentrations of total T3 and T4, free T4, rT3, TSH, TBG and cortisol were measured on arrival in hospital in 33 adult injured patients, 26 of whom were received directly from the accident. Serum cortisol levels and all thyroid indices, except TBG, were altered substantially by injury. Compared with values from 57 healthy volunteers, statistically significant (P less than 0.01) decreases were found in the mean serum free and total T4 concentrations and the rT3 level. Similarly significant (P less than 0.001) increases were seen in the mean serum T3, TSH and cortisol concentrations. Repeated assessment of thyroid function in six patients suggested a biphasic response to injury by TSH, T3 and rT3. The first phase was of short duration (1-2 h). Serum levels of TSH and T3 were above normal, and rT3 was decreased. These data suggest participation by the thyroid in the 'fight-or-flight' response to life-threatening stress. The second phase was fully established 6-18 h after injury and was characterized by reductions in serum TSH, T3 and total and free T4 and a rise in rT3. This pattern persisted throughout the 2-week period of measurement. Thus, as in other critical illnesses, the 'low T3' syndrome is common in severely injured patients. However, changes in thyroid hormone metabolism after injury are of greater intensity and longer duration.     

Comparison of pituitary-thyroid function in patients with endstage renal disease and in age- and sex-matched controls

The response to i.v. bolus thyrotropin-releasing hormone (TRH) of 14 dialysis patients with end-stage renal disease (ESRD) was compared to the response of 14 age- and sex-matched renal clinic patients (controls) with normal renal function (serum creatinine concentrations less than 1.2 mg/dl). The mean basal serum levels of thyrotropin (TSH) were similar in the two groups. There was no difference between the two groups in the mean maximal increase in TSH after TRH (6.3 microU/ml and 7.2 microU/ml in ESRD and control groups, respectively); The rate of fall in TSH from 60 to 90 min after TRH was slower in the ESRD group than in the controls. The mean increase in serum triiodothyronine (T3) concentration after TRH was similar in both groups (25.4 ng/dl, ESRD; 18.4 ng/dl, controls). As previously reported, basal serum T3 content was subnormal in the ESRD patients. Serum thyroxine (T4) concentrations were comparable in control and ESRD groups and did not change significantly during the 90-min TRH test in either group. We conclude that ESRD patients, clinically stable on dialysis, have normal pituitary TRH responsiveness and normal thyroidal response to endogenous TSH secretion, as compared with an age- and sex-matched group of patients with normal renal function. The results of this study support the contention that ESRD patients are eumetabolic.     

Thyroid function tests in patients undergoing maintenance dialysis: characterization of the 'low-T4 syndrome' in subjects on regular hemodialysis and continuous ambulatory peritoneal dialysis

Thyroid function tests were evaluated in 38 patients on regular hemodialysis (HD), in 36 on continuous ambulatory peritoneal dialysis (CAPD) and in 39 healthy controls. A significant reduction in total thyroxine (TT4), total triiodothyronine (TT3), reverse (rT3), and free T4 (fT4) mean levels and normal TSH, free T3, TBG and albumin concentrations was found in both HD and CAPD patients. A 'low-T4 syndrome' (serum T4 less than 5 micrograms/dl) was found in 9 CAPD (25%) and 20 HD (53%) patients, but none of them had fT4 levels below the normal laboratory range. The only striking difference between low-T4 HD and low-T4 CAPD patients was the significantly lower TBG and albumin serum levels in CAPD group. Low-T4 HD displayed normal TBG levels but enhanced fT4/TT4 and fT4/TT4 X TBG ratios. We concluded that: the abnormalities in thyroid function tests in patients on long-term dialysis (HD and CAPD) do not express the existence of a true hypothyroidism; a different pathogenesis of the low-T4 syndrome in the CAPD and HD groups may be hypothesized: in the former it could be attributed to a reduction in serum-binding capacity for thyroid hormones, in the latter the relative increase in fT4 percentage despite normal TBG levels suggests either the presence of T4-TBG-binding inhibitor(s), or structural abnormalities of thyroid-hormone-binding proteins.     

Serum oxytocin concentrations in elective caesarean delivery: a randomized comparison of three infusion regimens

Background

The aim of this study was to determine serum oxytocin concentrations following different regimens of prophylactic oxytocin administration in women undergoing elective caesarean delivery.

Methods

Thirty healthy pregnant patients were randomized, after clamping of the umbilical cord, to receive intravenous oxytocin in one of the following groups: G1 (n = 9), 10 IU of oxytocin infused over 30 min (0.33 IU/min); G2 (n = 11), 10 IU of oxytocin infused over 3 min and 45 s (2.67 IU/min); and G3 (n = 10), 80 IU of oxytocin infused over 30 min (2.67 IU/min). Both patient and surgeon were blinded to allocation. Uterine tone was assessed by surgical palpation. Serum oxytocin concentration was determined by enzyme immunoassay before anaesthesia (T0) and at 5 (T5), 30 (T30) and 60 (T60) min after the start of oxytocin infusion.

Results

Serum oxytocin concentrations (mean ± standard error, ng/mL) were not significantly different in the groups at T0 (0.06±0.02, 0.04±0.02 and 0.07±0.04, respectively, P = 0.76), and T60 (0.65±0.26, 0.36±0.26 and 0.69±0.26, respectively, P = 0.58). G3 showed higher concentrations than G1 at T5 (3.65±0.74 versus 0.71±0.27, P = 0.01) and at T30 (6.19±1.19 versus 1.17±0.37, P < 0.01), and were higher than G2 at T30 (6.19±1.19 versus 0.41±0.2, P < 0.01). Haemodynamic data and uterine tone were considered satisfactory and similar in all groups. No additional uterotonic agents were needed.

Conclusion

Serum oxytocin measurements made using enzyme immunoassay in healthy pregnant women undergoing elective caesarean delivery showed that administration of 80 IU oxytocin over 30 min resulted in higher serum oxytocin levels after 5 and 30 min than the two other regimens. The concentrations did not differ between groups at 60 min.     

The role of thyroid dysfunction in the critically ill: a review of the literature

During critical illness, patients with no known history of thyroid disorders may experience multiple alterations in their serum thyroid hormone levels. Such alterations have been termed sick euthyroid syndrome or, more recently, non-thyroidal illness syndrome (NTIS). The laboratory parameters of NTIS usually include low serum levels of triiodothyronine (T3), normal or low serum levels of thyroxine (T4) and normal or low serum levels of thyroid-stimulating hormone (TSH). The magnitude of the alteration in thyroid function correlates with the severity of the illness and its outcomes in critically ill patients with NTIS. The pathogenetic mechanisms involved in NTIS include a decreased conversion of T4 to T3 in extrathyroidal tissues and alterations in thyroid hormones' binding to serum proteins. In cases of protracted critical illness, a decrease in the pulsatile frequency of TSH secretion, resulting from reduced thyrotropin-re leasing hormone (TRH) release by the hypothalamus, may also occur. Several medications or clinical conditions that are commonly present in critically ill patients may be responsible for lowering serum concentrations of thyroid hormone. Among those who study the condition, the question of whether NTIS is a protective adaptation of the organism to illness or a maladaptive response to a stressful insult remains unanswered. In either case, thyroid hormone abnormalities are likely to play a role in the critically ill patient.However, there is currently no convincing evidence to suggest that restoring physiological thyroid hormone concentrations in unselected patients with NTIS would be beneficial.     

The effect of surgery with carbohydrate infusion on circulating triiodothyronine and reverse triiodothyronine.

The blood levels of thyrotrophin (TSH), thyroxine (T4), triiodothyronine (T3), and reverse triiodothyronine (rT3) were measured in a group of patients undergoing cholecystectomy and receiving 2000 kcal of glucose daily throughout the study. TSH changes suggested a peroperative peak followed by a fall and subsequent rise. T4 showed no significant changes. T3 fell and rT3 rose postoperatively, with a highly significant fall in the T3/rT3 ratio (p less than 0.001). Surgery and carbohydrate deprivation separately result in similar changes. However, the demonstration of the changes after injury despite adequate carbohydrate intake strongly suggests that they are a primary response to surgery and not a secondary response to the normal consequential fall in caloric and carbohydrate intake. The changes could be an appropriate adaptation to the changed metabolic requirements.