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.

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.

Free thyroxine assessed with three assays in sera of patients with nonthyroidal illness and of subjects with abnormal concentrations of thyroxine-binding proteins

1993 ◽  
Vol 39 (8) ◽  
pp. 1668-1674 ◽  
Author(s):  
R Docter ◽  
H van Toor ◽  
E P Krenning ◽  
M de Jong ◽  
G Hennemann
Keyword(s):  
Blood Donors ◽  
Reference Range ◽  
Equilibrium Dialysis ◽  
Free Thyroxine ◽  
Serum Samples ◽  
Nonthyroidal Illness ◽  
Nonesterified Fatty Acids ◽  
Thyroxine Binding Globulin ◽  
Control Value ◽  
The Mean

Abstract Three methods for estimating free thyroxine (FT4) in serum were studied: equilibrium dialysis, the SPAC-ET FT4 radioimmunoassay kit, and the Amerlite MAB FT4 luminometric assay. Serum samples from 10 subjects with above-normal thyroxine-binding globulin (TBG), 6 with low TBG, 30 with familial dysalbuminemic hyperthyroxinemia (FDH), 13 with nonesterified fatty acids (NEFA) concentrations in serum &gt; 1.0 mmol/L, and 178 patients with various degrees of nonthyroidal illness (NTI) were measured and compared with samples from 42 euthyroid blood donors. The Amerlite MAB FT4 assay compared well with equilibrium dialysis, whereas the SPAC-ET assay averaged 40% lower. All three assays were not influenced by changes in TBG and showed no or only little changes in the presence of NEFA. Mean FT4 values in the FDH samples were somewhat higher than in controls when measured with the SPAC-ET assay, about equal with equilibrium dialysis, and somewhat below the mean control value with the Amerlite MAB FT4 assay, although individual results were within the control reference range. In NTI patients, no FT4 values were below the control reference range by the Amerlite MAB FT4 assay, 4 of 178 were below this range by equilibrium dialysis, and 1 of 178 was below this range by the SPAC-ET assay. In all assays a large proportion of the NTI samples showed FT4 values above the control reference range, a result that will interfere with the efficacy of these assays for assessing thyroid function in NTI patients.

Pictorial reporting of multiple thyroid function results.

1976 ◽  
Vol 22 (10) ◽  
pp. 1562-1566
Author(s):  
R W Pain ◽  
B M Duncan
Keyword(s):  
Thyroid Function ◽  
Reporting System ◽  
Free Thyroxine ◽  
Thyroid Function Tests ◽  
Testing Procedures ◽  
Function Tests ◽  
Free Thyroxine Index ◽  
Total Thyroxine ◽  
Experience Difficulty

Abstract Clinicians experience difficulty in correctly interpreting the results of in vitro thyroid function tests in the presence of abnormalities of thyrobinding proteins or when results are borderline. This difficulty has been largely resolved in our laboratory by three innovations. First, the borderline areas for each of three routine tests of thyroid function (total thyroxine, thyrobinding index, and free thyroxine index) were accurately determined. Second, the results from this routine profile of three tests were displayed pictorially so as to produce patterns characteristic of various diagnostic situations, including euthyroidism in the presence of abnormalities of thyrobinding proteins. Third, interpretive comments and, in the case of borderline patterns, suggested further testing procedures were added to the report. Clinicians find the reporting system helpful and respond when additional tests are suggested. The system, operated manually at first, was later computerized.

Lacking evidence for release of thyroid hormones from circulating thyroglobulin during subtotal thyroidectomy

1988 ◽  
Vol 117 (2) ◽  
pp. 219-224 ◽  
Author(s):  
J. Date ◽  
M. Blichert-Toft ◽  
U. Feldt-Rasmussen ◽  
V. Haas
Keyword(s):  
Thyroid Hormones ◽  
Mean Value ◽  
Thyroid Stimulating Hormone ◽  
Mean Values ◽  
Thyroid Resection ◽  
Free Thyroxine Index ◽  
Total Triiodothyronine ◽  
Total Thyroxine ◽  
The Mean ◽  
Peak Value

Abstract. The effect of subtotal thyroid resection for thyrotoxicosis on concentrations of serum thyroid hormones and thyroglobulin (Tg), was determined in 10 patients during operation and the subsequent 18 days. Mean serum Tg responded drastically, increasing from a pre-operative value of 0.30 nmol/l to a peak value of approximately 26 nmol/l during operation followed by a gradual decline to levels lower than before surgery on day 18. Mean serum total thyroxine was 114 nmol/l pre-operatively and free thyroxine index (FT4I) 105 units. Both fluctuated only slightly during operation. Postsurgically, the mean values decreased to below 50% of the pre-operative level. Mean serum total triiodothyronine (TT3) was 1.46 nmol/l pre-operatively. It decreased during operation, reaching a nadir of 0.55 nmol/l on day 2, whereafter the concentration increased slightly. Mean serum reverse T3 (rT3) was 0.45 nmol/l pre-operatively, increased 62% during surgery, and decreased postsurgically. The mean value of serum thyroid stimulating hormone (TSH) was 0.61 mU/l pre-operatively and remained below 1 mU/l during and after operation, but from day 10 concentration began to rise steadily. It is concluded that the vast release of Tg during thyroid resection did not contribute to the concentration of serum T4 to an extent of clinical relevance.

Liquid chromatography and fluorescence polarization immunoassay methods compared for measuring flecainide acetate in serum.

1987 ◽  
Vol 33 (10) ◽  
pp. 1898-1900 ◽  
Author(s):  
R J Straka ◽  
T J Hoon ◽  
R L Lalonde ◽  
J A Pieper ◽  
M B Bottorff
Keyword(s):  
Liquid Chromatography ◽  
Fluorescence Polarization ◽  
High Performance ◽  
Therapeutic Drug ◽  
Fluorescence Polarization Immunoassay ◽  
Serum Samples ◽  
Coefficients Of Variation ◽  
Flecainide Acetate ◽  
Assay Methods ◽  
The Mean

Abstract We analyzed 99 patients' serum samples for concentrations of a new antiarrhythmic agent, flecainide acetate, by fluorescence polarization immunoassay (FPIA) and "high-performance" liquid chromatography (HPLC). Within-day and between-day coefficients of variation at concentrations in the low and high ends of the therapeutic range were less than 7% for HPLC and less than 9% for FPIA. There was no statistical difference in the mean (+/- SD) concentrations of the clinical serum samples measured by the two methods (607 +/- 334 micrograms/L by HPLC, 602 +/- 344 micrograms/L by FPIA), but results by each differed by a mean of 0.13%. FPIA and HPLC measurements correlated significantly (r = 0.98, P less than 0.05), and were linearly related (slope = 0.970, intercept = 13 micrograms/L) as assessed by orthogonal regression. Both assay methods produced similar concentration measurements and were sufficiently accurate and precise to be used in therapeutic drug monitoring.

SERUM TRI-IODOTHYRONINE UPTAKE USING COATED CHARCOAL IN THE ASSESSMENT OF THYROID FUNCTION

1968 ◽  
Vol 41 (1) ◽  
pp. 31-40 ◽  
Author(s):  
W. J. IRVINE ◽  
RUTH M. STANDEVEN
Keyword(s):  
Significant Variation ◽  
Blood Donors ◽  
Age Groups ◽  
Free Thyroxine ◽  
Degree Of Saturation ◽  
Free Thyroxine Index ◽  
Good Distinction ◽  
Uptake Test ◽  
Uptake Method ◽  
Normal Controls

SUMMARY A modification of the tri-iodothyronine T3 uptake test using coated charcoal has been developed. When the method was compared with the resin sponge test, the charcoal method was found to be more rapid, accurate and economical. For patients who were not pregnant or receiving drugs known to affect the degree of saturation of thyroxine-binding globulin, the T3 charcoal uptake method made a good distinction between the hyperthyroid and euthyroid patients but the distinction between the hypothyroid and euthyroid patients was less satisfactory. Separation between the three groups of patients was improved by using the product of the T3 uptake and protein-bound iodine measurement (the free thyroxine index). The [125I]T3 charcoal results are reported for 199 blood donors as normal controls. A sex difference was apparent but there was no significant variation in the age groups studied (18–60 yr.). Thirty-seven pregnant women were studied. Calculation of the free thyroxine index did not give results within the non-pregnant euthyroid range.

HYPOTHALAMIC ENDOCRINE DYSFUNCTION IN ANOREXIA NERVOSA

1977 ◽  
Vol 85 (4) ◽  
pp. 673-683 ◽  
Author(s):  
Antti Aro ◽  
B.-A. Lamberg ◽  
Risto Pelkonen
Keyword(s):  
Growth Hormone ◽  
Anorexia Nervosa ◽  
Diurnal Variation ◽  
Plasma Cortisol ◽  
Free Thyroxine ◽  
Inadequate Response ◽  
Serum Growth Hormone ◽  
Hormone Levels ◽  
Free Thyroxine Index ◽  
The Mean

ABSTRACT The hypothalamic-pituitary function of 21 women with anorexia nervosa, aged 15–34 years, was studied. The tests included, in addition to the usual tests of thyroid function, a TRH stimulation test with 200 μg of synthetic TRH given iv; the response of serum immunoreactive growth hormone to insulin; and the diurnal variation and response of plasma cortisol to insulin hypoglycaemia. The mean serum TSH level of the patients was higher than that of healthy controls. The mean maximal increment of TSH after TRH was similar in the patients and the controls. However, 18 of the patients but none of the controls showed a delayed TSH-response to TRH, i. e. the TSH-level at 60 min was higher than that recorded 20 min after TRH. Four of the patients had a low free thyroxine index, computed from the PBI and T3 Sephadex uptake values, and 3 of these were clinically hypothyroid. The means for PBI, T4 and the free thyroxine index were all significantly below the means for the controls. The basal serum growth hormone levels were increased in 9 out of 17 patients. In 4 of these an inadequate response to insulin or to glucagon was found. In 5 out of the 8 patients with normal basal growth hormone levels a normal response was found, whereas the remaining 3 showed a subnormal response. The serum growth hormone level was correlated with the degree of weight loss but not with the serum albumin concentration. Plasma cortisol at 08.00 was increased in 9 patients and the diurnal variation was inadequate in 6. Four patients showed a subnormal response to insulin-induced hypoglycaemia, and 2 out of 5 patients tested failed to show adequate suppression of plasma cortisol after 1 mg of dexamethasone. Dysfunction of the hypothalamic-pituitary axis is common in anorexia nervosa. A delayed TSH-response to TRH, compatible with hypothalamic dysfunction, seems to be an almost consistent feature of the disorder, and in some of the patients even clinical hypothalamic hypothyroidism may be evident.

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