Serum free thyroxine concentrations measured by chemiluminescence in hyperthyroid and euthyroid cats

1996 ◽  
Vol 32 (6) ◽  
pp. 489-494 ◽  
Author(s):  
M Paradis ◽  
N Page
Keyword(s):  
Thyroid Function ◽  
Reference Values ◽  
Free Thyroxine ◽  
Radioactive Materials ◽  
Serum Free ◽  
Clinically Normal ◽  
Serum Free Thyroxine

Serum free thyroxine (FT4) concentrations using chemiluminescence were measured in hyperthyroid cats (n = 72) and clinically normal cats (n = 129) to establish reference values and to determine if this method could be a useful alternative to total T4 (TT4) measurement by radioimmunoassay (RIA). Mean serum FT4 concentration (68.3 +/- 26.8 pmol/L) of hyperthyroid cats was significantly higher than that of euthyroid cats (22.9 +/- 4.8 pmol/L). Reference values for basal FT4 of hyperthyroid and healthy cats were 33 to 114 pmol/L and 16 to 30 pmol/L, respectively. The results of the present study suggest that FT4 measured by chemiluminescence could be a useful alternative to TT4 measured by RIA when evaluating thyroid function in cats, since the hazardous effects of radioactive materials on the manipulators and the environment could be avoided. Further studies are required to corroborate these preliminary findings.

scholarly journals L-T4 Therapy in the Presence of Pharmacological Interferents

2020 ◽  
Vol 11 ◽  
Author(s):  
Salvatore Benvenga
Keyword(s):  
Thyroid Function ◽  
Cardiovascular Complications ◽  
Primary Hypothyroidism ◽  
Free Thyroxine ◽  
Thyroid Function Tests ◽  
Central Hypothyroidism ◽  
Serum Free ◽  
Function Tests ◽  
Frequent Monitoring ◽  
Serum Free Thyroxine

Pharmacological interference on L-thyroxine (L-T4) therapy can be exerted at several levels, namely from the hypothalamus/pituitary through the intestine, where the absorption of exogenous L-T4 takes place. A number of medications interfere with L-T4 therapy, some of them also being the cause of hypothyroidism. The clinician should be aware that some medications simply affect thyroid function tests with no need of modifying the dose of L-T4 that the patient was taking prior to their prescription. Usually, the topic of pharmacological interference on L-T4 therapy addresses the patient with primary hypothyroidism, in whom periodic measurement of serum thyrotropin (TSH) is the biochemical target. However, this minireview also addresses the patient with central hypothyroidism, in whom the biochemical target is serum free thyroxine (FT4). This minireview also addresses two additional topics. One is the costs associated with frequent monitoring of the biochemical target when L-T4 is taken simultaneously with the interfering drug. The second topic is the issue of metabolic/cardiovascular complications associated with undertreated hypothyroidism.

A Case Series of Patients With Central Hypothyroidism From Oxcarbazepine Therapy

2020 ◽  
pp. 088307382096292 ◽  
Author(s):  
Bahareh Michelle Schweiger ◽  
Aaron-James Lao ◽  
Jane Tavyev
Keyword(s):  
Thyroid Function ◽  
Pediatric Population ◽  
Case Series ◽  
Metabolic Enzymes ◽  
Thyroid Stimulating Hormone ◽  
Free Thyroxine ◽  
Central Hypothyroidism ◽  
Serum Free ◽  
Serum Free Thyroxine ◽  
Stimulating Hormone

Many medications can impact thyroid function. Antiseizure medications have been shown to disrupt thyroid function in adults, but information is limited about how antiseizure medications may affect thyroid function in children. Oxcarbazepine is an analog of carbamazepine designed to minimize effects from the hepatic P450 metabolic enzymes. We have found that in the pediatric population, serum free thyroxine is reduced and thyroid-stimulating hormone concentrations are unchanged in patients taking oxcarbazepine with the mechanism thus being central hypothyroidism.

Factors Affecting the Serum Free Thyroxine Levels in Hospitalized Chronic Geriatric Patients

1993 ◽  
Vol 41 (7) ◽  
pp. 742-746 ◽  
Author(s):  
Istvan Szabolcs ◽  
Christoph Ploenes ◽  
Mathias Beyer ◽  
Wolfdieter Bernard ◽  
Jorg Herrmann
Keyword(s):  
Geriatric Patients ◽  
Free Thyroxine ◽  
Factors Affecting ◽  
Serum Free ◽  
Serum Free Thyroxine

scholarly journals Serum Free Thyroxine and Triiodothyronine Concentrations in Subacute Thyroiditis

1980 ◽  
Vol 56 (11) ◽  
pp. 1527-1534
Author(s):  
Katsumi YOSHIDA ◽  
Toshiro SAKURADA ◽  
Nobuko KAISE ◽  
Kazuo KAISE ◽  
Hirofumi KITAOKA ◽  
...  
Keyword(s):  
Free Thyroxine ◽  
Subacute Thyroiditis ◽  
Serum Free ◽  
Serum Free Thyroxine

scholarly journals Serum free thyroxine levels are associated with the efficacy of weight reduction therapy in obese female patients

2016 ◽  
Vol 63 (3) ◽  
pp. 221-229 ◽  
Author(s):  
Koshi Hashimoto ◽  
Tetsuya Tagami ◽  
Hajime Yamakage ◽  
Kazuya Muranaka ◽  
Masashi Tanaka ◽  
...  
Keyword(s):  
Weight Reduction ◽  
Free Thyroxine ◽  
Serum Free ◽  
Female Patients ◽  
Obese Female ◽  
Serum Free Thyroxine

scholarly journals Misleading results from immunoassays of serum free thyroxine in the presence of rheumatoid factor

1997 ◽  
Vol 43 (6) ◽  
pp. 957-962 ◽  
Author(s):  
Anthony G W Norden ◽  
Rodwin A Jackson ◽  
Lorraine E Norden ◽  
A Jane Griffin ◽  
Margaret A Barnes ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Rheumatoid Factor ◽  
Equilibrium Dialysis ◽  
Thyroid Stimulating Hormone ◽  
Normal Serum ◽  
Free Thyroxine ◽  
Free Triiodothyronine ◽  
Serum Free ◽  
Serum Free Thyroxine ◽  
Stimulating Hormone

Abstract A novel interference with measurements of serum free thyroxine (FT4) caused by rheumatoid factor (RhF) is described. We found misleading, sometimes gross, increases of FT4 results in 5 clinically euthyroid elderly female patients with high RhF concentrations. All 5 patients had high FT4 on Abbott AxSYM® or IMx® analyzers. “NETRIA” immunoassays gave misleading results in 4 of the 5 patients; Amerlex-MAB® in 2 of 4 patients; AutoDELFIA®in 2 of the 5; and Corning ACS-180® and Bayer Diagnostics Immuno 1® in 1 of the 5. BM-ES700® system results for FT4 in these women remained within the reference range. Results for serum T4, thyroid-stimulating hormone, free triiodothyronine, thyroid-hormone-binding globulin, and FT4 measured by equilibrium dialysis were normal in all 5 patients. Drugs, albumin-binding variants, and anti-thyroid-hormone antibodies were excluded as interferences. Addition to normal serum of the RhF isolated from each of the 5 patients increased the apparent FT4 (Abbott AxSYM). Screening of 83 unselected patients demonstrated a highly significant positive correlation between FT4 (Abbott AxSYM) and RhF concentrations. Discrepant, apparently increased FT4 with a normal result for thyroid-stimulating hormone should lead to measurement of the patient’s RhF concentration.

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