The triiodothyronine uptake test: an assessment of methods.

1981 ◽  
Vol 27 (7) ◽  
pp. 1272-1276 ◽  
Author(s):  
L R Witherspoon ◽  
S E Shuler ◽  
M M Garcia
Keyword(s):  
Functional Status ◽  
Coefficient Of Variation ◽  
Temperature Effects ◽  
Thyroxine Binding Globulin ◽  
Wide Range ◽  
Free Thyroxine Index ◽  
Total Thyroxine ◽  
Multiple Measurements ◽  
Uptake Test ◽  
Commercial Kits

Abstract How well the free thyroxine index reflects thyroid functional status depends on the degree to which the triiodothyronine uptake test normalizes the effects of thyroxine binding protein concentrations on the total thyroxine concentration. We examined eight triiodothyronine uptake tests in which were used different secondary binders representative of those available in commercial kits. The relation between triiodothyronine uptake and thyroxine-binding globulin concentrations was established by use of sera from euthyroid individuals. We examined the effects of both high (greater than 20 mg/L) and low (less than 10 mg/L) thyroxine-binding globulin concentrations on triiodothyronine uptake. The precision of each assay, expressed as within- and between-run coefficient of variation, was calculated from multiple measurements on high, low, and midrange triiodothyronine uptake serum pools. The effects of variation in temperature and in exposure times were examined. The clinical most useful assays exhibited the ability to reflect a wide range of thyroxine-binding globulin concentrations and demonstrated little or no time or temperature effects.

Evaluation of serum triiodothyronine and adjusted triiodothyronine (free triiodothyronine index) in pregnancy.

1977 ◽  
Vol 23 (3) ◽  
pp. 490-492 ◽  
Author(s):  
M E Parslow ◽  
T H Oddie ◽  
D A Fisher
Keyword(s):  
Free Thyroxine ◽  
Free Triiodothyronine ◽  
Thyroxine Binding Globulin ◽  
Serum Thyroxine ◽  
Free Thyroxine Index ◽  
Total Triiodothyronine ◽  
Total Thyroxine ◽  
Highly Correlated ◽  
Normal Men ◽  
Male Subjects

Abstract We measured serum thyroxine (free and total), triiodothyronine (free and total), thyroxine-binding globulin, and triiodothyronine uptake by talc in 97 normal men and 50 pregnant women. Mean serum thyroxine and triiodothyronine concentrations were higher in the pregnant subjects (104 vs. 78 mug/liter and 1.69 vs. 1.30 mug/liter) because of a higher mean thyroxine-binding globulin concentration (70 vs. 38 mg/liter). Mean triiodothyronine uptake by talc was lower in the pregnant subjects (0.82 vs. 1.03). Mean free thyroxine concentrations were similar in the two groups, but mean free triiodothyronine concentrations were 10% lower in the pregnant subjects. Triiodothyronine uptake by talc and the diayzable thyroxine and triiodothyronine fractions were highly correlated (r = 0.85 and r = 0.82, P less than 0.001). Calculated free thyroxine index and free triiodothyronine index values (hyroxine and triiodothyronine indirectly adjusted, using triiodothyronine talc uptake to compensate for differences in thyroxine-binding globulin concentration), were statistically similar (84 vs. 82 and 1.38 vs. 1.34) in pregnant and male subjects. The results indicate that the total triiodothyronine concentration can be normalized on the basis of the triiodothyronine uptake by talc to correct for variations in thyroxine-binding globulin concentration.

Thyroxine and Thyroxine-Binding Globulin: Discriminant Formulae for the Separation of the Diagnostic Classes of Thyroid Function

1984 ◽  
Vol 21 (1) ◽  
pp. 40-42 ◽  
Author(s):  
Dennis A Noe
Keyword(s):  
Functional Status ◽  
Thyroid Function ◽  
Reference Range ◽  
Reference Ranges ◽  
Linear Discriminant ◽  
Thyroxine Binding Globulin ◽  
Wide Range ◽  
Reference Limits ◽  
Diagnostic Index

The biochemical classification of thyroid functional status is often accomplished by the use of the thyroxine to thyroxine-binding globulin (T4:TBG) ratio. It has recently been shown, however, that the reference range of the T4:TBG ratio varies with the concentration of TBG. This makes the T4:TBG ratio an unwieldy diagnostic index. A more accurate and economical way to define thyroid function using T4 and TBG measurements is by linear discriminant formulae. This is so because T4 varies linearly with TBG at the T4 reference limits over a wide range of TBG concentrations. Using the T4 reference ranges established by Attwood and Atkin ( Ann Clin Biochem 1982; 19: 101–3), the following formulae are obtained: T4 (nmol/l)—4·05 TBG (mg/l)>94·5 indicates hyperthyroidism; T4 (nmol/l)—2·72 TBG (mg/l)<23·8 identifies hypothyroidism.

scholarly journals Thyroid Hormone Concentrations and Free Thyroxine Status in Neonatal Venous and Capillary Serum Pairs

1984 ◽  
Vol 21 (4) ◽  
pp. 306-309 ◽  
Author(s):  
Collen M O'Grady ◽  
R C Franklin
Keyword(s):  
Free Thyroxine ◽  
Sample Collection ◽  
Serum Samples ◽  
Term Neonates ◽  
Paired Samples ◽  
Free Thyroxine Index ◽  
Total Thyroxine ◽  
Assay Methods ◽  
The Mean ◽  
Uptake Test

The levels of thyroid hormones in paired venous and capillary serum samples taken from 68 healthy full-term neonates were determined by radioimmunoassay. Compared with capillary values, total thyroxine (T4), thyrotropin (TSH) and thyroxine-binding globulin (TBG) each showed a significant decrease in venous serum. The mean venous and capillary concentrations of tri-iodothyronine (T3), reverse tri-iodothyronine (rT3) and free thyroxine (fT4) were not significantly different; however, in each case the fitted linear relationship suggested that venous and capillary values were not concordant ( P<0·02, P<0·01, P<0·05 respectively). Both the T3 uptake test and the free thyroxine index (FTI) were significantly higher in venous serum, while the ratios of T4 to TBG in paired samples were equivalent. These results suggest that consistent sample collection and assay methods should be applied when assessing neonatal thyroid status, particularly if comparison of results is intended.

Radioimmunoassay of Thyroxine-Binding Globulin: Evaluation of a Kit and Diagnostic Application

1980 ◽  
Vol 17 (5) ◽  
pp. 241-246 ◽  
Author(s):  
J Ahmed ◽  
P Smethurst
Keyword(s):  
Confidence Limit ◽  
Late Pregnancy ◽  
Thyroid Function Test ◽  
Mean Value ◽  
Thyroxine Binding Globulin ◽  
Function Test ◽  
Free Thyroxine Index ◽  
The Mean ◽  
Uptake Test ◽  
Radioimmunoassay Method

Serum thyroxine-binding globulin (TBG) was measured by using a radioimmunoassay method. The within-batch coefficient of variation (CV) of the assay was 5 % or less at different TBG concentrations with a between-batch variation of less than 10%. The mean TBG concentration in hypothyroidism (28·5 ±6·7 mg/l) was significantly higher, and that in hyperthyroidism (22·3 ±3·5 mg/l) was significantly lower, than the euthyroid mean (25·4 ±6·9 mg/l). Acutely ill patients suffering from various non-thyroidal illnesses were found to have significantly low mean TBG (13·8 ± 4·3 mg/l). A group of women in late pregnancy had a higher mean value, as expected. Serum TBG level, however, was ineffective as a thyroid function test because of overlapping concentrations between groups. The derived index T4:TBG ratio was found to be superior to free thyroxine index (FTI) in many cases of acutely ill patients, pregnancy, and hereditary TBG abnormality. The 95% confidence limit for the ratio in euthyroids was 2·3 to 7·1. Serum TBG level with T4:TBG ratio is recommended as a replacement for the T3-uptake test and FTI.

ENDOCRINE CHANGES BEFORE AND AFTER THE MENARCHE

1973 ◽  
Vol 74 (4) ◽  
pp. 685-694 ◽  
Author(s):  
B.-A. Lamberg ◽  
R.-L. Kantero ◽  
P. Saarinen ◽  
O. Widholm
Keyword(s):  
Binding Proteins ◽  
Maturation Process ◽  
Hormone Binding ◽  
Maximal Level ◽  
Continuous Increase ◽  
Mean Values ◽  
Thyroxine Binding Globulin ◽  
Before And After ◽  
Free Thyroxine Index ◽  
Level 1

ABSTRACT In an endocrine survey of healthy girls aged 8 to 20 years before and after the menarche, the serum thyroxine (T4), uptake of triiodothyronine by Sephadex (T3U), and the binding capacities of thyroxine binding globulin (TBG) and pre-albumin (TBPA) were measured, and a free thyroxine index (FTI = T4 × T3U) was calculated. The subjects were grouped according to skeletal age (SA) until the menarche and after this in the post-menarcheal age (PMA), expressed in years. T4 and FTI increased concomitantly and reached peak values of 8.40 μg/100 ml and 8.40, respectively, at 2–3 years PMA. The corresponding mean values for post-menarcheal girls (7.74 μg/100 ml and 7.51) differed statistically significantly from the means before the menarche (7.03 μg/ 100 ml and 6.75). The TBG remained virtually unchanged during the whole period, whereas the TBPA showed a continuous increase and reached a maximal level 1–2 years after the menarche. The maturation process in girls in some way involves an increase in the total and free T4 level which is not dependent on hormone binding proteins.

Research of the activity and viability of spermatozoa at different concentrations and proportions of diluents after incubation

2020 ◽  
pp. 88-95
Author(s):  
Svitlana Lobchenko ◽  
Tetiana Husar ◽  
Viktor Lobchenko
Keyword(s):  
Plasma Concentration ◽  
Incubation Time ◽  
Coefficient Of Variation ◽  
Incubation Medium ◽  
Wide Range ◽  
Series Of Experiments ◽  
The Subject ◽  
Boar Spermatozoa ◽  
Native Plasma ◽  
Better Than

The results of studies of the viability of spermatozoa with different incubation time at different concentrations and using different diluents are highlighted in the article. (Un) concentrated spermatozoa were diluented: 1) with their native plasma; 2) medium 199; 3) a mixture of equal volumes of plasma and medium 199. The experiment was designed to generate experimental samples with spermatozoa concentrations prepared according to the method, namely: 0.2; 0.1; 0.05; 0.025 billion / ml. The sperm was evaluated after 2, 4, 6 and 8 hours. The perspective of such a study is significant and makes it possible to research various aspects of the subject in a wide range. In this regard, a series of experiments were conducted in this area. The data obtained are statistically processed and allow us to highlight the results that relate to each stage of the study. In particular, in this article it was found out some regularities between the viability of sperm, the type of diluent and the rate of rarefaction, as evidenced by the data presented in the tables. As a result of sperm incubation, the viability of spermatozoa remains at least the highest trend when sperm are diluted to a concentration of 0.1 billion / ml, regardless of the type of diluent used. To maintain the viability of sperm using this concentration of medium 199 is not better than its native plasma, and its mixture with an equal volume of plasma through any length of time incubation of such sperm. Most often it is at this concentration of sperm that their viability is characterized by the lowest coefficient of variation, regardless of the type of diluent used, which may indicate the greatest stability of the result under these conditions. The viability of spermatozoa with a concentration of 0.1 billion / ml is statistically significantly reduced only after 6 or even 8 hours of incubation. If the sperm are incubated for only 2 hours, regardless of the type of diluent used, the sperm concentrations tested do not affect the viability of the sperm. Key words: boar, spermatozoa, sperm plasma, concentration, incubation, medium 199, activity, viability, rarefaction.

FAMILIAL THYROXINE-BINDING GLOBULIN DEFICIENCY IN ASSOCIATION WITH NON-TOXIC GOITRE

1979 ◽  
Vol 91 (1) ◽  
pp. 70-76 ◽  
Author(s):  
Paul Bratusch-Marrain ◽  
Hannes Haydl ◽  
Werner Waldhäusl ◽  
Robert Dudczak ◽  
Wolfgang Graninger
Keyword(s):  
Clinical Evidence ◽  
Autosomal Dominant ◽  
Serum Concentrations ◽  
Dominant Inheritance ◽  
Normal Range ◽  
Thyroxine Binding Globulin ◽  
The Family ◽  
High Incidence ◽  
Total Thyroxine ◽  
Mode Of Transmission

ABSTRACT A kindred is presented in which 4 members in 3 generations showed absent or reduced serum concentrations of thyroxine-binding globulin (TBG). TBG was undetectable by radioimmunoassay in one male and decreased to varying extent in 3 female patients (4.0, 4.2 and 8.6 μg/ml; normal range 12.5–26.0 μg/ml). Total thyroxine serum concentrations in the affected subjects were well in the hypothyroid range without clinical evidence of hypothyroidism. The mode of transmission of the trait was consistent with X-chromosome linkage. A high incidence of non-toxic goitre was also present in most of the family members examined irrespective of TBG levels. The transmission of the goitre trait was compatible with autosomal dominant inheritance. Thus its association with transmission of TBG deficiency was interpreted as not causal but coincidental.

scholarly journals Subgrid snow depth coefficient of variation spanning alpine to sub-alpine mountainous terrain

2021 ◽  
Author(s):  
Graham A. Sexstone ◽  
Steven R. Fassnacht ◽  
Juan I. López-Moreno ◽  
Christopher A. Hiemstra
Keyword(s):  
Coefficient Of Variation ◽  
Land Surface ◽  
Snow Depth ◽  
Mountainous Terrain ◽  
Mountainous Regions ◽  
Scale Modeling ◽  
Roughness Elements ◽  
Wide Range ◽  
Performance Statistics ◽  
Snowpack Properties

Given the substantial variability of snow in complex mountainous terrain, a considerable challenge of coarse scale modeling applications is accurately representing the subgrid variability of snowpack properties. The snow depth coefficient of variation (CVds) is a useful metric for characterizing subgrid snow distributions but has not been well defined by a parameterization for mountainous environments. This study utilizes lidar-derived snow depth datasets spanning alpine to sub-alpine mountainous terrain in Colorado, USA to evaluate the variability of subgrid snow distributions within a grid size comparable to a 1000 m resolution common for hydrologic and land surface models. The subgrid CVds exhibited a wide range of variability across the 321 km2 study area (0.15 to 2.74) and was significantly greater in alpine areas compared to subalpine areas. Mean snow depth was the dominant driver of CVds variability in both alpine and subalpine areas, as CVds decreased nonlinearly with increasing snow depths. This negative correlation is attributed to the static size of roughness elements (topography and canopy) that strongly influence seasonal snow variability. Subgrid CVds was also strongly related to topography and forest variables; important drivers of CVds included the subgrid variability of terrain exposure to wind in alpine areas and the mean and variability of forest metrics in subalpine areas. Two statistical models were developed (alpine and subalpine) for predicting subgrid CVds that show reasonable performance statistics. The methodology presented here can be used for characterizing the variability of CVds in snow-dominated mountainous regions, and highlights the utility of using lidar-derived snow datasets for improving model representations of snow processes.

TRH (Thyroid-Releasing Hormone) Tests

1984 ◽  
Vol 6 (6) ◽  
pp. 189-190
Keyword(s):  
Binding Proteins ◽  
Elevated Serum ◽  
Graves Disease ◽  
Base Line ◽  
Trh Test ◽  
Thyroxine Binding Globulin ◽  
Serum Thyroxine ◽  
Free Thyroxine Index ◽  
Serum T4 ◽  
Line Test

I have read with great interest "Goiter in Children" by Foley (PIR 1984;5:259). The author stated: "In patients with thyromegaly and mild symptoms of hyperthyroidism, a TRH test will help to discriminate hyperthyroxemia secondary to increased or abnormal serum thyroxine binding proteins from early Graves disease, factitious hyperthyroidism, toxic thyroiditis, and TSH-mediated hyperthyroidism." I would suggest the use of a triiodothyronine (T3) resin uptake as a base-line test. An elevated serum thyroxine (T4) value in conjunction with a diminished T3 resin uptake suggests thyroxine-binding globulin (TBG) excess, which can be confirmed by specific quantitation of TBG. Patients with familial dysalbuminemic hyperthyroxinemia (FDH) have elevated levels of serum T4 and free thyroxine index (FT4l) values but normal T3 resin uptake and TBG levels.

Cavitation in a high-speed aviation axial piston pump over a wide range of fluid temperatures

2021 ◽  
pp. 095765092110469
Author(s):  
Qun Chao ◽  
Zi Xu ◽  
Jianfeng Tao ◽  
Chengliang Liu ◽  
Jiang Zhai
Keyword(s):  
Temperature Effects ◽  
Pressure Pulsation ◽  
Piston Pump ◽  
Limiting Factors ◽  
Fluid Temperature ◽  
Cfd Model ◽  
Axial Piston Pump ◽  
Wide Range ◽  
Fluid Properties ◽  
Axial Piston

The axial piston pump in aerospace applications needs to operate over a wide range of fluid temperatures from −54°C to 135 °C. The fluid properties at such extreme temperatures will significantly affect the cavitation that is one of the major limiting factors for the efficiency and reliability of aviation axial piston pumps. However, it appears that very little of the existing literature studies the effects of extreme fluid temperatures on the pump cavitation. This paper aims to examine the temperature effects on the cavitation in an aviation axial piston pump. First, we develop a three-dimensional (3D) transient computational fluid dynamics (CFD) model to investigate the pump cavitation and validate it experimentally. Second, we use the validated CFD model to investigate the temperature effects on the pump cavitation by changing the fluid properties including viscosity, density, and bulk modulus. The numerical results show that low fluid temperature makes the aviation axial piston pump suffer serious cavitation due to high viscosity, leading to delivery flow breakdown, unacceptable pressure pulsation, and delayed pressure built up. In contrast, high fluid temperatures have minor effects on the cavitation although they increase the pressure pulsation and built-up time slightly.

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