Automated tests for the assessment of thyroid function.

Fully automated methods have been developed for the determination of thyroxine and triiodothyronine levels, antibodies to thyroglobulin and the assessment of thyroid hormone binding proteins in serum, using a continuous flow radioimmunoassay system. In addition the feasibility of a partially automated assay for thyrotrophin levels has been demonstrated. These employ Auto Analyzer modules and antibodies covalently linked to a magnetisable solid phase support. Separation of bound and free antigen is achieved by applying an external magnetic field. The system currently operates at a rate of 30 samples/h and requires only 10 minutes incubation since it is not necessary to reach equilibrium. The results are similar to those obtained by conventional manual techniques, however the precision is improved and operator error eliminated.     

The plasma estradiol as an index of fetoplacental function

A radioligand assay has been developed for the measurement of unconjugated 17beta-estradiol in as little as 0.01 ml of pregnancy plasma employing rabbit uterine cytosol as specific binder and activated charcoal as nonspecific absorbant. Large numbers of samples could be processed simultaneously at relatively little expense and results were obtainable within 3 hr. The procedure was sensitive to 1 ng/ml. No diurnal or positional variations were found. Values from 250 unselected normal patients showed a constantly rising mean plasma E(2) from 18 to 35 wk gestation from 4.5 to 14 ng/ml. From 35 to 40 wk, mean E(2) rose only to 15 ng/ml and the range of values increased substantially. When 22 normal pregnant subjects were followed serially, rising levels of plasma E(2) were found with no significant fall ever seen. By contrast, patients exhibiting fetal distress generally had falling or reduced E(2) levels. However, 3 cases of Rh isoimmunization had elevated or normal E(2) concentrations even after clearcut evidence of fetal demise. A decrease of 45% in E(2) concentration was associated with intraamniotic instillation of hypertonic saline prior to delivery supporting the view that placental conversion of maternal adrenal precursors is responsible for about half of the E(2) production in pregnancy. The postpartum clearance of endogenous E(2) was measured and found to fit a two compartment model with mean half-time of 22 min and 7 hr. Follicular phase levels of E(2) were attained by 35 hr postpartum. The concentration of unconjugated E(2) in pregnancy plasma correlated as well with the state of the placenta as other placental hormone measurements and holds promise of being a rapid, inexpensive, and reliable method of following patients with high-risk pregnancies in a variety of clinical settings.     

Increased sensitivity of the thyroid in iodine-depleted rats to the goitrogenic effects of thyrotropin

The present studies demonstrate that iodine depletion increases the sensitivity of the thyroid to the goitrogenic effects of thyrotropin. Iodine depletion was induced by feeding rats a low iodine diet containing propylthiouracil for 10-14 days before hypophysectomy. Accumulation of iodine in the thyroid after hypophysectomy was prevented by continuing the antithyroid drugs in the diet. Doses of thyrotropin as low as 3 mU/100 g of body weight per day produced significant thyroid enlargement in 3-7 days in iodine-depleted rats. Adding propylthiouracil or perchlorate to the diet during treatment with thyrotropin did not reduce or augment the goitrogenic response to thyrotropin in iodine-depleted rats. Increasing the level of circulating iodide also did not reduce the goitrogenic response to thyrotropin. The increased sensitivity of the iodine-depleted thyroid gland may provide an explanation for the development of thyroid enlargement without requiring an increased level of circulating thyrotropin.     

Evaluation of the usefulness of a sensitive immunoradiometric assay for thyroid stimulating hormone as a first-line thyroid function test in an unselected patient population

A new sensitive immunoradiometric assay for serum thyroid stimulating hormone (TSH) was applied to 1627 consecutive patients from four large clinics at Malm? General Hospital, in whom a thyroid function disorder was suspected. The final diagnoses were taken from the patients' charts at a follow-up 1-2 years after the primary evaluation. If only those patients without thyroid disease were used as a reference population, the 5th percentile was 0.8 mIU/l. When this cutoff limit was applied to the unselected patient population, the TSH assay had a high sensitivity for the diagnosis of hyperthyroidism (96%), a lower specificity (64%) and a very low predictive value (10%). Therefore, in the majority of the patients (72%) the sensitive TSH assay cannot be used alone to define thyroid function.     

Evaluation of perfusion index as a tool for pain assessment in critically ill patients

Pain is a common and undertreated problem in critically ill patients. Pain assessment in critically ill patients is challenging and relies on complex scoring systems. The aim of this work was to find out the possible role of the perfusion index (PI) measured by a pulse oximeter (Masimo Radical 7; Masimo Corp., Irvine, CA, USA) in pain assessment in critically ill patients. A prospective observational study was carried out on 87 sedated non-intubated patients in a surgical intensive care unit. In addition to routine monitoring, a Masimo pulse oximeter probe was used for PI measurement. The sedation level of the patients was assessed by using the Richmond Agitation-Sedation Scale (RASS). The pain intensity was determined by applying the behavioral pain scale for non-intubated (BPS-NI) patients. The PI, arterial blood pressure, heart rate, RASS, and BPS-NI values before and after the application of a standard painful stimulus (changing the patient position) were reported. Correlation between the PI and other variables was carried out at the two measurements. Correlation between changes in the PI (delta PI) and in the hemodynamic variables, RASS, and BPS-NI was also done. Changing the patient position resulted in a significant increase in SBP (128 ± 20 vs 120.4 ± 20.6, P = 0.009), DBP (71.3 ± 11.2 vs 68.7 ± 11.3, P = 0.021), heart rate (99.5 ± 19 vs 92.7 ± 18.2, P = 0.013), and BPS-NI (7[6–8] vs 3[3–3], P < 0.001) values and a significant decrease in the PI (1[0.5–1.9] vs 2.2[0.97–3.6], P < 0.001) value compared to the baseline readings. There was no correlation between the values of the PI and the ABP, BPS-NI, and RASS at the two measurements. A good correlation was found between the delta PI and delta BPS-NI (r = ?0.616, P < 0.001). A weak correlation was observed between the PI and heart rate after the patient positioning (r = ?0.249, P < 0.02). In surgical critically ill non-intubated patients, the application of a painful stimulus was associated with decreased PI. There was a good correlation between the change in the PI and the change in BPS-NI values after the application of painful stimulus.     

Neutrophil iodination micro-method as an index of neutrophil and opsonic function

A neutrophil iodination micro-method has been developed for assessment of neutrophil and opsonic function in any serum/micro-organism combination. The test is performed in micro-titre trays and thus requires relatively small amounts of reagents and numbers of cells. The variables of the test have been explored and the effect of immunization with different organisms on opsonin levels defined. The versatility of the test has been demonstrated in its ability to measure both heat labile and heat stable opsonins in normal as well as immune serum, for a number of different micro-organisms. The method is simple, rapid and a large number of tests can be performed at the one time.     

Doppler echocardiographic index for assessment of global right ventricular function

Echocardiographic assessment of right ventricular function remains difficult and challenging. However, there is considerable clinical need for a simple, reproducible, and reliable parameter of right ventricular function in patients with right-sided heart disease. The purpose of this study was to assess the clinical value of a Doppler-derived index, combining systolic and diastolic intervals of the right cycle, in assessing global right ventricular function in patients with primary pulmonary hypertension. The study population comprised 26 consecutive patients with primary pulmonary hypertension and 37 age-matched normal subjects. The sum of right ventricular isovolumetric contraction time and isovolumetric relaxation time was obtained by subtracting right ventricular ejection time from the interval between cessation and onset of the tricuspid inflow velocities with pulsed-wave Doppler echocardiography. An index of combined right ventricular systolic and diastolic function was obtained by dividing the sum of both isovolumetric intervals by ejection time. The index was compared with available parameters of systolic or diastolic function, clinical symptoms, and survival. Right ventricular isovolumetric contraction time and isovolumetric relaxation time were prolonged significantly in patients with primary pulmonary hypertension (85 ± 41 msec and 135 ± 43 msec) compared with normal subjects (38 ± 7 msec and 49 ± 9 msec, respectively; p < 0.001). Ejection time was shortened significantly in patients with pulmonary hypertension (241 ± 43 msec versus normal [322 ± 21 msec]; p < 0.001). However, the index was the single most powerful variable to discriminate patients with primary pulmonary hypertension from normal subjects (0.93 ± 0.34 versus 0.28 ± 0.04; p < 0.001) and was the strongest predictor of clinical status and survival. The index was not significantly affected by heart rate, right ventricular pressure, right ventricular dilation, or tricuspid regurgitation. It is well known that right ventricular systolic and diastolic dysfunction coexist in patients with primary pulmonary hypertension. This article reports the use of an easily obtainable Doppler-derived index that combines elements of systolic and diastolic function. This index appears to be a useful noninvasive means that correlates with symptoms and survival in patients with primary pulmonary hypertension.     

Data-reduction methods for immunoradiometric assays of thyrotropin compared

In an attempt to optimize curve fitting for immunoradiometric assays, we investigated eight data-reduction methods with two commercially available assays of thyrotropin. In four of these methods linear data-reduction models are used: logit-log programs of Iso-Data, Micromedic, and Hewlitt-Packard, and probit-log of Hewlitt-Packard. The other four were nonlinear data-reduction models: Iso-Data's "French curve" (modified spline), four-parameter logistic function, and point-to-point methods, as well as a nonlinear least squares method. In using the eight data-reduction methods on data from analyses of 78 patients' samples, we found clinically relevant differences between models. In fact, differences found by changing data-reduction models were greater than the difference between the two commercial kits.     

Comparative evaluation of serum thyroxine, free thyroxine and thyrotropin determinations in screening of thyroid function

We assessed a highly sensitive immunoradiometric thyrotropin (TSH) assay in screening thyroid dysfunction in 130 consecutive outpatients from a department of medicine and 224 patients from a municipal health centre. In addition to clinical examination, three routine tests were done: a thyroxine radioimmunoassay, an analogue-based free thyroxine assay and an immunoradiometric TSH assay. Triiodothyronine and the TRH test were done, if the findings were discrepant. Discrepancy existed in 24% of cases. The TSH assay had no false negative results (sensitivity 100%). Therefore TSH could screen all patients with thyroid dysfunction. Free thyroxine was the most specific assay (specificity 96%), but many subclinically or overtly hypothyroid patients would have been missed, if that assay had been used alone. We conclude that TSH(IRMA) is the best first-line measurement for thyroid dysfunction testing among outpatients. An abnormal TSH result alone is not diagnostic, but should be followed by the measurement of thyroxine or free thyroxine.     

妊娠期甲状腺自身抗体检测对糖尿病产妇甲状腺功能评估的价值

目的探讨检测妊娠期甲状腺自身抗体对妊娠期糖尿病(GDM)产妇甲状腺功能的评估价值。方法选择2014年2~8月在该院确诊为GDM的产妇140例纳入观察组,80例健康产妇纳入对照组。检测促甲状腺素(TSH)、三碘甲状腺原氨酸(T3)、甲状腺素(T4)、游离三碘甲状腺原氨酸(FT3)、游离甲状腺素(FT4)、抗甲状腺球蛋白抗体(TGAb)和抗甲状腺过氧化物酶抗体(TPOAb)。结果两组产妇TSH、T3、T4、FT3水平相比,差异无统计学意义(P0.05);观察组FT4水平低于对照组,差异有统计学意义(P0.05);观察组TGAb、TPOAb及二者联合检测阳性率均明显高于对照组,差异有统计学意义(P0.05)。结论甲状腺抗体检测对GDM产妇甲状腺功能评价具有重要作用,能及时发现甲状腺病变,有利于改善妊娠结局。