scholarly journals The T4:TBG Ratio: A Re-Evaluation with Particular Reference to Low and High Serum TBG Levels

1982 ◽  
Vol 19 (2) ◽  
pp. 101-103 ◽  
Author(s):  
E C Attwood ◽  
G E Atkin
Keyword(s):  
Retrospective Study ◽  
Thyroid Function ◽  
Reference Range ◽  
High Serum ◽  
Reference Ranges ◽  
Thyroid Function Tests ◽  
Thyroxine Binding Globulin ◽  
Biochemical Investigation ◽  
Small Increments ◽  
Routine Assay

The thyroxine: thyroxine-binding globulin (T4: TBG) ratio is now an established part of the biochemical investigation of thyroid function. Reference ranges have been reported for euthyroid subjects with TBG levels within the range 6–16 mg/l. Routine assay of TBG on all thyroid function tests in this laboratory has suggested that, in patients with low or high TBG levels, the established reference ranges for T4:TBG may not be strictly applicable. A retrospective study has been made of a large number of thyroid function requests, including serum total T4, free T4, TBG, and TSH assays. Evidence is presented to show that in subjects with a TBG level of less than 8 mg/l the reference range for T4: TBG is elevated. Similarly, in subjects with a TBG greater than 16 mg/l, the reference range for T4: TBG is lowered. The data suggest that it is necessary to quote a T4: TBG reference range based on small increments of TBG levels or to relate total T4 reference ranges to those increments.

Thyroid Function Tests in Thyroxine-Binding Globulin Deficiency

1979 ◽  
Vol 16 (1-6) ◽  
pp. 313-314 ◽  
Author(s):  
C. F. Cusick
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Function ◽  
Reference Range ◽  
Free Thyroxine ◽  
Thyroid Function Tests ◽  
Thyroid Status ◽  
Thyroxine Binding Globulin ◽  
Serum Thyroxine ◽  
Function Tests ◽  
Lowered Serum

Results are presented on two patients with complete and two with partial thyroxinebinding globulin (TBG) deficiency. All four subjects had lowered serum thyroxine but were clinically euthyroid. While thyroid hormone uptake tests or TBG assay were effective in the recognition of such individuals, indices based on these tests were misleading in assessing their thyroid status. Results within the reference range were obtained with the Immophase Free Thyroxine assay.

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 Plasma mineral (selenium, zinc or copper) concentrations in the general pregnant population, adjusted for supplement intake, in relation to thyroid function

2020 ◽  
Vol 125 (1) ◽  
pp. 71-78
Author(s):  
Victor Pop ◽  
Johannes Krabbe ◽  
Wolfgang Maret ◽  
Margaret Rayman
Keyword(s):  
Thyroid Function ◽  
Reference Range ◽  
First Trimester ◽  
Future Research ◽  
Thyroid Peroxidase ◽  
Reference Ranges ◽  
Lower Plasma ◽  
The Mean ◽  
The Impact ◽  
Supplement Intake

AbstractThe present study reports on first-trimester reference ranges of plasma mineral Se/Zn/Cu concentration in relation to free thyroxine (FT4), thyrotropin (TSH) and thyroid peroxidase antibodies (TPO-Ab), assessed at 12 weeks’ gestation in 2041 pregnant women, including 544 women not taking supplements containing Se/Zn/Cu. The reference range (2·5th–97·5th percentiles) in these 544 women was 0·72–1·25 µmol/l for Se, 17·15–35·98 µmol/l for Cu and 9·57–16·41 µmol/l for Zn. These women had significantly lower mean plasma Se concentration (0·94 (sd 0·12) µmol/l) than those (n 1479) taking Se/Zn/Cu supplements (1·03 (sd 0·14) µmol/l; P < 0·001), while the mean Cu (26·25 µmol/l) and Zn (12·55 µmol/l) concentrations were almost identical in these sub-groups. Women with hypothyroxinaemia (FT4 below reference range with normal TSH) had significantly lower plasma Zn concentrations than euthyroid women. After adjusting for covariates including supplement intake, plasma Se (negatively), Zn and Cu (positively) concentrations were significantly related to logFT4; Se and Cu (but not Zn) were positively and significantly related to logTSH. Women taking additional Se/Zn/Cu supplements were 1·46 (95 % CI 1·09, 2·04) times less likely to have elevated titres of TPO-Ab at 12 weeks of gestation. We conclude that first-trimester Se reference ranges are influenced by Se-supplement intake, while Cu and Zn ranges are not. Plasma mineral Se/Zn/Cu concentrations are associated with thyroid FT4 and TSH concentrations. Se/Zn/Cu supplement intake affects TPO-Ab status. Future research should focus on the impact of trace mineral status during gestation on thyroid function.

Young adult reference ranges for thyroid function tests on the Centaur immunoassay analyser

2006 ◽  
Vol 63 (4) ◽  
pp. 163-165 ◽  
Author(s):  
M. Alqahatani ◽  
W. Tamimi ◽  
M Aldaker ◽  
F. Alenzi ◽  
H. Tamim ◽  
...  
Keyword(s):  
Young Adult ◽  
Thyroid Function ◽  
Reference Ranges ◽  
Thyroid Function Tests ◽  
Function Tests

scholarly journals Durvalumab-induced diabetic ketoacidosis followed by hypothyroidism

2019 ◽  
Vol 2019 ◽  
Author(s):  
Shivani Patel ◽  
Venessa Chin ◽  
Jerry R Greenfield
Keyword(s):  
Diabetic Ketoacidosis ◽  
Thyroid Function ◽  
Immune Checkpoint ◽  
Immune Checkpoint Inhibitor ◽  
Reference Range ◽  
Checkpoint Inhibitor ◽  
Autoimmune Diabetes ◽  
Inhibitor Therapy ◽  
Thyroid Function Tests ◽  
Checkpoint Inhibitor Therapy

Summary Durvalumab is a programmed cell death ligand 1 inhibitor, which is now approved in Australia for use in non-small-cell lung and urothelial cancers. Autoimmune diabetes is a rare immune-related adverse effect associated with the use of immune checkpoint inhibitor therapy. It is now being increasingly described reflecting the wider use of immune checkpoint inhibitor therapy. We report the case of a 49-year-old female who presented with polyuria, polydipsia and weight loss, 3 months following the commencement of durvalumab. On admission, she was in severe diabetic ketoacidosis with venous glucose: 20.1 mmol/L, pH: 7.14, bicarbonate 11.2 mmol/L and serum beta hydroxybutyrate: >8.0 mmol/L. She had no personal or family history of diabetes or autoimmune disease. Her HbA1c was 7.8% and her glutamic acid decarboxylase (GAD) antibodies were mildly elevated at 2.2 mU/L (reference range: <2 mU/L) with negative zinc transporter 8 (ZnT8) and islet cell (ICA) antibodies. Her fasting C-peptide was low at 86 pmol/L (reference range: 200–1200) with a corresponding serum glucose of 21.9 mmol/L. She was promptly stabilised with an insulin infusion in intensive care and discharged on basal bolus insulin. Durvalumab was recommenced once her glycaemic control had stabilised. Thyroid function tests at the time of admission were within normal limits with negative thyroid autoantibodies. Four weeks post discharge, repeat thyroid function tests revealed hypothyroidism, with an elevated thyroid-stimulating hormone (TSH) at 6.39 mIU/L (reference range: 0.40–4.80) and low free T4: 5.9 pmol/L (reference range: 8.0–16.0). These findings persisted with repeat testing despite an absence of clinical symptoms. Treatment with levothyroxine was commenced after excluding adrenal insufficiency (early morning cortisol: 339 nmol/L) and hypophysitis (normal pituitary on MRI). Learning points: Durvalumab use is rarely associated with fulminant autoimmune diabetes, presenting with severe DKA. Multiple endocrinopathies can co-exist with the use of a single immune checkpoint inhibitors; thus, patients should be regularly monitored. Regular blood glucose levels should be performed on routine pathology on all patients on immune checkpoint inhibitor. Clinician awareness of immunotherapy-related diabetes needs to increase in an attempt to detect hyperglycaemia early and prevent DKA.

scholarly journals Is It T3 Thyrotoxicosis? A Case of Falsely Elevated Tri-Iodothyronine (T3) Levels Leading to a Diagnosis of Multiple Myeloma

2019 ◽  
Vol 2019 ◽  
pp. 1-3
Author(s):  
Nanik Ram ◽  
Saira Furqan ◽  
Sibtain Ahmed
Keyword(s):  
Multiple Myeloma ◽  
Thyroid Function ◽  
Reference Range ◽  
Thyroid Function Tests ◽  
Laboratory Parameters ◽  
Laboratory Results ◽  
Monoclonal Immunoglobulins ◽  
Spurious Results ◽  
Endocrinology Clinic ◽  
Assay Interference

We are presenting a case of falsely elevated T3 levels in a patient due to interference from monoclonal immunoglobulins. A 56-year-old, clinically euthyroid man referred to the endocrinology clinic of the Aga Khan university, Karachi Pakistan, for possible T3 thyrotoxicosis after thyroid function tests revealed total T3 >12.32 nmol/L (reference range 0.6–2.79), normal TSH, and total T4 level. There was a mismatch in clinical and laboratory parameters and preliminary laboratory results were suggestive of thyroid binding globulin abnormalities. Further evaluation in this context unmasked multiple myeloma. The presence of monoclonal immunoglobulins can lead to assay interference and spurious results. To the best of our knowledge, this is the second case defining the cause of falsely elevated T3 levels, due to assay interferences with binding of T3 only to monoclonal immunoglobulins.

Changes in Thyroid Function Across Adolescence: A Longitudinal Study

2020 ◽  
Vol 105 (4) ◽  
pp. e1162-e1170 ◽  
Author(s):  
Purdey J Campbell ◽  
Suzanne J Brown ◽  
Phillip Kendrew ◽  
Michelle Lewer ◽  
Ee Mun Lim ◽  
...  
Keyword(s):  
Thyroid Function ◽  
Twin Study ◽  
Specific Reference ◽  
Sexually Dimorphic ◽  
Reference Ranges ◽  
Thyroid Function Tests ◽  
Longitudinal Analyses ◽  
Free Triiodothyronine ◽  
Longitudinal Twin Study ◽  
Abbott Architect

Abstract Objective There are no large, longitudinal studies of thyroid function across adolescence. The aims of this study were to examine longitudinal trends in thyrotropin (TSH), free triiodothyronine (fT3) and free thyroxine (fT4) and determine age-specific reference ranges. Methods Thyroid function was assessed in 3415 participants in the Brisbane Longitudinal Twin Study at ages 12, 14, and 16, using the Abbott ARCHITECT immunoassay. Longitudinal analyses were adjusted for body mass index and puberty. Results In girls, mean fT4 (± SE) increased between age 12 and 14 (by 0.30 ± 0.08 pmol/L; P &lt; 0.001), while remaining unchanged in boys; from age 14 to 16, fT4 increased in both girls (by 0.42 ± 0.07 pmol/L; P &lt; 0.001) and boys (0.64 ± 0.07 pmol/L, P &lt; 0.001). There was a slight increase in fT3 from age 12 to 14 years in girls (by 0.07 ± 0.03 pmol/L; P = 0.042), with a more marked increase in boys (0.29 ± 0.03 pmol/L; P &lt; 0.001), followed by a decrease from age 14 to 16 in both sexes (girls, by 0.53 ± 0.02 pmol/L; P &lt; 0.001; boys, by 0.62 ± 0.03 pmol/L; P &lt; 0.001). From age 12 to 14, TSH showed no significant change in girls or boys, then levels increased from age 14 to 16 in both sexes (in girls, by 4.9%, 95% CI: 2.4%-10.3%, P = 0.020; in boys, by 7.2%, 95% CI: 3.0%-11.6%, P = 0.001). Reference ranges differed substantially from adults, particularly for fT4 and fT3. Conclusions Thyroid function tests in adolescents display complex, sexually dimorphic patterns. Implementation of adolescence-specific reference ranges may be appropriate.

Trimester-specific reference ranges for thyroid function tests in South Indian women

2018 ◽  
Vol 15 (3) ◽  
pp. 117
Author(s):  
Vijaya Sarathi ◽  
KSandhya Rani ◽  
Sunanda Tirupati ◽  
KDileep Kumar
Keyword(s):  
Thyroid Function ◽  
Specific Reference ◽  
Reference Ranges ◽  
Thyroid Function Tests ◽  
Indian Women ◽  
Function Tests ◽  
South Indian

Long term changes in serum T4, T3, and TSH in benign thyroid disease

2004 ◽  
Vol 43 (05) ◽  
pp. 158-160 ◽  
Author(s):  
F. Hartmann ◽  
R. Rödel ◽  
M. Reinhardt ◽  
H.-J. Biersack
Keyword(s):  
Thyroid Function ◽  
Small Variation ◽  
Reference Ranges ◽  
Thyroid Function Tests ◽  
Free T4 ◽  
Wide Range ◽  
Serum T4 ◽  
The Individual ◽  
Benign Thyroid

Summary:Aim: The diagnosis of abnormalities of thyroid function is generally based on the measurement of thyroid hormones and TSH in blood. The recommended reference ranges for serum T4 and T3 as well as TSH are quite wide as the result of large differences in thyroid function tests in healthy persons. It has been proven that the individual variation within an individual is small, compared with the variation between individuals. We investigated long term variations of these parameters in patients with and without benign thyroid diseases. Methods: We performed long term follow-up serum determinations of T3, T4, and TSH in a total of 150 patients for a time period of 3 to 13 years. The majority of patients had been put on L-thyroxine. Values of total T3, total T4, free T4 were measured with an almost unmodified test (RIA) over the years. Results: The lowest relative coefficient of variation (<10%) was observed in the group of patients who had been treated with L-thyroxine only. Even for TSH, relatively low cofficients of variation were observed in this group. In the group of patients who had not received any medication, T3 and T4 showed also a variation of 10%. FT4 and TSH revealed a wider range of variation. Even after radioiodine therapy, T3 and T4 showed only a quite small variation, while TSH demonstrated a wide range with a variation of >30%. Conclusion: Our data demonstrate that there are only narrow variations of serum T4 and T3 within individuals with and without thyroid disorders.

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