Free thyroxin by radioimmunoassay: evaluation of a new direct method involving a radiolabeled thyroxin analog.

1983 ◽  
Vol 29 (10) ◽  
pp. 1781-1786 ◽  
Author(s):  
N P Kubasik ◽  
P A Lundberg ◽  
R G Brodows ◽  
G D Hallauer ◽  
D G Same ◽  
...  
Keyword(s):  
Performance Evaluation ◽  
Oral Contraceptives ◽  
Thyroid Disease ◽  
Direct Method ◽  
Age Effect ◽  
Free T4 ◽  
Nonthyroidal Illness ◽  
Serum Free ◽  
Normal Individuals ◽  
The Mean

Abstract We present here the first performance evaluation of a new direct method for free thyroxin (T4) in serum by radioimmunoassay, with use of coated tubes and a radiolabeled T4 analog (Diagnostic Products Corp.). The assay is precise and robust: within-run imprecision (CV), 3.1-6.6%; between-run imprecision, 4.0-7.9%; no demonstrable variation between technologists irrespective of experience with the method. No outliers were observed when we compared the free T4 results with serum total T4. Reference values are reported for a total of 1243 euthyroid subjects; there was no significant age effect on serum free T4 in women 26 to 72 years old. The biological variation was about +/- 35% of the mean (2 SD). Free T4 results are the same for serum and plasma. The assay performs well in hypothyroidism and hyperthyroidism, and distinguishes individuals with thyroid disease from normal individuals. Free T4 values in women taking oral contraceptives are normal. Depressed results were often observed in acute nonthyroidal illness and continuing pregnancy. These results were directly comparable with those of another commercial direct radiolabeled-T4 analog kit for free T4.

Screening for thyroid disease in women greater than or equal to 50 years of age seeking hospital care: influence of common nonthyroidal illness on serum free thyroxin as determined by analog radioimmunoassay.

1986 ◽  
Vol 32 (4) ◽  
pp. 603-608 ◽  
Author(s):  
E Nyström ◽  
K Petersen ◽  
G Lindstedt ◽  
P A Lundberg
Keyword(s):  
Acute Care ◽  
Outpatient Clinic ◽  
Clinical Setting ◽  
Thyroid Disease ◽  
Hospital Care ◽  
Nonthyroidal Illness ◽  
Serum Free ◽  
Simple Analog ◽  
Acute Medical Care ◽  
Medical Outpatients

Abstract We determined free thyroxin (fT4; analog radioimmunoassay) and thyrotropin in serum of women greater than or equal to 50 years of age who were attending a medical casualty ward (n = 363) or a medical outpatient clinic (n = 496), in order to estimate the prevalence of low fT4 results associated with nonthyroidal illness and to screen for previously unknown thyroid disease. Individuals with results outside stated limits were followed up within two to four weeks. Only about 5% of the women seeking acute medical care showed a decrease in fT4 concentration in association with a normal thyrotropin concentration. As expected, this combination was even less common in outpatients. We found a prevalence of previously undiagnosed thyroid disease of clinical significance of 0.8% in medical acute-care cases, 1.8% in medical outpatients. For this clinical setting we regard the simple analog technique as acceptable in spite of the low values reported for some hospitalized patients with nonthyroidal illness.

Improved dialysis method for free thyroxin in serum compared with five commercial radioimmunoassays in nonthyroidal illness and subjects with abnormal concentrations of thyroxin-binding globulin.

1983 ◽  
Vol 29 (5) ◽  
pp. 816-822 ◽  
Author(s):  
T Helenius ◽  
K Liewendahl
Keyword(s):  
Clinical Laboratory ◽  
Late Pregnancy ◽  
Third Trimester ◽  
Free T4 ◽  
Nonthyroidal Illness ◽  
Mean Values ◽  
The Third ◽  
Dialysis Method ◽  
The Mean ◽  
Low Serum

Abstract We describe a method for free thyroxin (FT4) in serum, based on radioimmunoassay of T4 in serum dialysate, FT4(D). The method is analytically accurate, sensitive, reproducible, and suitable for routine use in the clinical laboratory. We compared results by this method with those obtained with five commercial FT4 assays (Amerlex, GammaCoat, ImmoPhase, LiquiSol, Spiria) and the free T4 index (FT4I). In several of the patients with nonthyroidal illness FT4(D) was above normal and FT4 as measured with the commercial assays was subnormal. In the third trimester of pregnancy all the FT4 methods gave decreased mean values, though the decreases were of various magnitudes: FT4(D) 32%, Amerlex 44%, GammaCoat 40%, Spiria 19%, LiquiSol 16%, and ImmoPhase 13%, respectively. FT4I was significantly higher than normal during late pregnancy. In women taking oral contraceptives the mean FT4I was increased, but there was no significant effect on the results obtained with the various FT4 methods. All subjects with hereditarily high or low serum thyroxin-binding globulin had normal FT4(D) and abnormal FT4I. Amerlex, ImmoPhase, and LiquiSol misclassified some of the subjects with hereditarily abnormal thyroxin-binding globulin.

Low Free T3 Is Associated With Worse Outcomes in Patients in the ICU Requiring Invasive Mechanical Ventilation

2019 ◽  
pp. 088506661989082 ◽  
Author(s):  
Gary D. Rothberger ◽  
Paul K. Valestra ◽  
Khalilah Knight ◽  
Anish K. Desai ◽  
Rose Calixte ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Hospital Mortality ◽  
Invasive Mechanical Ventilation ◽  
Free Triiodothyronine ◽  
Nonthyroidal Illness ◽  
Serum Free ◽  
Entire Cohort ◽  
The Mean ◽  
Poor Outcomes ◽  
The Impact

Objective: Critical illness causes a decrease in serum free triiodothyronine (T3) levels. This condition, known as nonthyroidal illness syndrome (NTIS), is associated with poor outcomes. The association of NTIS and outcomes in patients in the intensive care unit (ICU) requiring mechanical ventilation has not been well studied. This study aimed to determine the impact of NTIS on the outcomes of these patients. Methods: This prospective study included 162 patients in the ICU who underwent mechanical ventilation. Serum free T3 levels were tested on the day of initiation of mechanical ventilation. The rates of in-hospital mortality and ventilator-free days (VFDs) at day 28 after the initiation of mechanical ventilation were compared between patients with low (<2.3 pg/mL) and normal (≥2.3 pg/mL) free T3 levels. Patients who died while on mechanical ventilation were assigned a VFD of 0. Results: Low T3 was present in 60% of study patients. The in-hospital mortality rate of the entire cohort was 39%, and the mean and median VFDs at day 28 were 13.5 and 21 days, respectively. Compared to patients with normal free T3, patients with low free T3 had higher in-hospital mortality (52% vs 19%, P < .001) and less mean and median VFDs at day 28 (10.7 vs 18 and 0 vs 23, respectively. P < .001 for both mean and median VFDs). Conclusions: The presence of low T3 due to NTIS in patients in the ICU requiring mechanical ventilation is associated with poor outcomes.

Concentration of free thyroxin in serum of a patient with euthyroid hyperthyroxinemia secondary to increased thyroxin-binding prealbumin: results by various methods compared.

1986 ◽  
Vol 32 (4) ◽  
pp. 687-689 ◽  
Author(s):  
D Skiest ◽  
L E Braverman ◽  
C H Emerson
Keyword(s):  
Equilibrium Dialysis ◽  
Single Step ◽  
Normal Range ◽  
Free T4 ◽  
Serum Free ◽  
Rare Syndrome ◽  
Serum T4 ◽  
The Mean ◽  
Euthyroid Hyperthyroxinemia ◽  
Range Free

Abstract We used various kits to measure free thyroxin (T4) in serum from a patient with the very rare syndrome of euthyroid hyperthyroxinemia secondary to increased thyroxin-binding prealbumin in serum. This patient's free T4 by equilibrium dialysis was 13 ng/L (normal 9-21), whereas the free-T4 index was 18.6 (normal 5.5-11.5). Using six different commercial methods, the last three listed being T4-analog methods, we measured the serum free T4 in this patient. The mean +/- SD (and normal range) free-T4 concentrations (ng/L) measured were: GammaCoat, Two-Step, 19.2 +/- 4.5 (6.9-26.9); Liquisol, 17.8 +/- 3.0 (12.4-20.8); Immo Phase, Two-Step 26.8 +/- 0.3 (12.4-21.2); GammaCoat, Single-Step, 19.7 +/- 5.7 (10.3-21.0); Immo Phase, Single-Step, 27.7 +/- 0.9 (8.6-25.0); and Amerlex, 14.1 +/- 0.6 (5.3-14.1). In four patients with familial dysalbuminemic hyperthyroidism, in whom the serum T4 by equilibrium dialysis was normal, all three T4-analog methods gave results far exceeding normal (greater than 50 ng/L).

SimulTRAC simultaneous radioimmunoassay of thyrotropin and free thyroxin evaluated.

1986 ◽  
Vol 32 (12) ◽  
pp. 2191-2194 ◽  
Author(s):  
S M Gow ◽  
G Caldwell ◽  
A D Toft ◽  
G J Beckett
Keyword(s):  
Thyroid Disease ◽  
Third Trimester ◽  
Nonthyroidal Illness ◽  
Dual Isotope ◽  
The Third ◽  
Analytical Recovery ◽  
Reference Limits ◽  
The Mean ◽  
Small Overlap ◽  
Good Agreement

Abstract We assessed the analytical and diagnostic performance of a dual-isotope RIA for thyrotropin (TSH) and free thyroxin (FT4) in serum. The mean interassay CVs for these analytes were 7.9% and 5.0%, respectively. The mean minimum detection limit for TSH was 0.25 milli-int. unit/L, the mean analytical recovery 110%. There was good agreement with values for TSH and FT4 measured by alternative RIA procedures. Euthyroid patients were well distinguished from those with overt thyroid disease, although there was a small overlap in the case of TSH. Combining the two results better discriminated these categories and identified those patients with subclinical thyroid disease who had abnormal TSH concentrations but FT4 concentrations within reference limits. Euthyroid women taking estrogen-containing oral contraceptives had normal results for TSH and FT4, as did most pregnant women studied. During the third trimester of pregnancy, TSH concentrations of women with low FT4 concentrations were within reference limits. Similarly, euthyroidism was confirmed in patients with low FT4 due to nonthyroidal illness by the simultaneous finding of a normal TSH concentration.

Specificity of sensitive assays of thyrotropin (TSH) used to screen for thyroid disease in hospitalized patients.

1987 ◽  
Vol 33 (8) ◽  
pp. 1391-1396 ◽  
Author(s):  
C Spencer ◽  
A Eigen ◽  
D Shen ◽  
M Duda ◽  
S Qualls ◽  
...  
Keyword(s):  
Thyroid Disease ◽  
Cost Effective ◽  
Reference Population ◽  
Reference Intervals ◽  
Hospitalized Patients ◽  
Nonthyroidal Illness ◽  
Thyroid Screening ◽  
Test Specificity ◽  
The Mean

Abstract Thyrotropin (TSH) concentrations were measured in 1580 hospitalized patients and 109 normal persons. Using the mean +/- 3 SD limits of the log values for the controls (0.35-6.7 milli-int. units/L), the proportion of abnormal TSH results in the hospitalized patients was 17.2%. TSH was undetectable (less than 0.1 milli-int. unit/L) in 3.1% of patients, suggesting hyperthyroidism, and high (greater than 20 milli-int. units/L) in 1.6%, suggesting hypothyroidism. On follow-up of 329 patients, 62% with abnormal TSH (less than 0.35 or greater than 6.7 milli-int. units/L) and 38% with normal TSH concentrations, only 24% of those with undetectable TSH had thyroid disease: 36% of them were being treated with glucocorticoids and 40% had nonthyroidal illness (NTI). Although half the patients with TSH greater than 20 milli-int. units/L had thyroid disease, 45% of patients had high TSH values associated with NTI. TSH concentrations usually returned towards normal when patients' therapy with glucocorticoids was discontinued or they recovered from NTI. TSH test sensitivity appeared good when the mean +/- 3 SD limits of the reference population were used, i.e., no cases of hyper- or hypothyroidism, as identified by free thyroxin index (FT4I), were missed. However, TSH test specificity was inferior to that of the FT4I test (90.7% vs 92.3%), although specificity could be improved to 97.0% if the wider TSH reference limits of 0.1 to 20 milli-int. units/L were used--limits considered pathological if applied to outpatients. Evidently, different reference intervals for TSH are needed for hospitalized and nonhospitalized patients. We conclude that a "sensitive TSH assay" is not a cost-effective thyroid screening test for hospitalized patients as compared with the FT4I.

Changes in Intraocular Pressure and Corneal and Retinal Nerve Fiber Layer Thicknesses in Hypothyroidism

2005 ◽  
Vol 15 (5) ◽  
pp. 556-561 ◽  
Author(s):  
U.A. Bahçeci ◽  
Ş. Özdek ◽  
Z. Pehlivanli ◽  
I. Yetkin ◽  
M. Önol
Keyword(s):  
Intraocular Pressure ◽  
Nerve Fiber ◽  
Retinal Nerve Fiber Layer ◽  
Scanning Laser ◽  
Fiber Layer ◽  
Serum Free ◽  
Correlation Test ◽  
Nerve Fiber Layer ◽  
The Mean ◽  
Spearman’S Correlation

Purpose To evaluate the changes in intraocular pressure (IOP), corneal thickness (CT), and retinal nerve fiber layer thickness (RNFLT) in patients with hypothyroidism before and after treatment. Methods A complete ophthalmic examination including visual acuity, IOP, anterior segment, and fundus examination together with CT and RNFLT measurements were performed for each patient with newly diagnosed hypothyroidism, at the initial diagnosis and the third and ninth months of the L-thyroxine treatment. Wilcoxon signed rank test and Spearman's correlation test were used for statistical evaluation of the results. Results A total of 56 eyes of 28 patients were included in the study. The mean IOP and CT values were found to decrease with medical treatment (p=0.000). There was no significant change in any of the RNFLT parameters measured with scanning laser Polarimeter after L-thyroxine treatment (Wilcoxon, p>0.05). The change in IOP levels was not correlated with the change in thyroid hormone levels (Spearman's correlation test, p>0.05). The mean increase in serum free T3 and serum free T4 levels and the mean decrease in serum TSH levels at the ninth month of the therapy were found to be correlated with the decrease in CT in the left eyes (Spearman's correlation test, R>0.4 and p<0.05). Conclusions Hypothyroidism seems to cause a reversible increase in CT and IOP. IOP changes may be secondary to CT changes. RNFLT parameters measured with scanning laser Polarimeter do not seem to be affected by hypothyroidism. When the CT is taken into account and the IOPs corrected for CT, the prevalence of glaucoma in hypothyroidism may not be as high as previously reported. This issue should be taken into account while assessing glaucoma in patients with hypothyroidism.

Quantitation of Albumin and Alpha-1-Acid Glycoprotein in Human Cervical Mucus

1991 ◽  
Vol 10 (2) ◽  
pp. 137-139 ◽  
Author(s):  
I.G. Salas Herrera ◽  
R.M. Pearson ◽  
P. Turner
Keyword(s):  
Oral Contraceptives ◽  
Genital Tract ◽  
Female Genital Tract ◽  
Cervical Mucus ◽  
Combined Oral Contraceptives ◽  
Acid Glycoprotein ◽  
Group A ◽  
The Mean ◽  
Group B ◽  
Female Genital

1 Concentrations of albumin and alpha-1-acid glycoprotein (AGP) in human cervical mucus have been measured by a radial immunodiffusion technique. 2 The cervical mucus samples were obtained from women on combined oral contraceptives (Group A) and from women not taking this medication (Group B). In group A the mean level of albumin was 75.6 (range 22-198) mg 1-1 and for AGP 6.5 (range 3-12) mg 1-1. In group B the mean level of albumin was 72.9 (range 22-148) mg 1-1 and for AGP 6.6 (range 3-14) mg 1 -1. 3 The levels of albumin and AGP in cervical mucus were less than 1% of the concentration in serum and were not affected by combined oral contraceptives. 4 The clinical and toxicological consequences of these observations, in terms of the disposition of drugs and other chemicals in the female genital tract, await elucidation.

Comparison of a new ultrafiltration method for serum free T4 and free T3 with two RIA kits in eight groups of patients

1985 ◽  
Vol 8 (6) ◽  
pp. 495-500 ◽  
Author(s):  
Yuh-Shyun Wang ◽  
A. E. Pekary ◽  
M. L. England ◽  
Jerome M. Hershman
Keyword(s):  
Free T4 ◽  
Serum Free ◽  
Free T3

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.

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