Free triiodothyronine to free thyroxine ratio in the differential diagnosis of thyrotoxicosis and hyperthyroidism: A retrospective study

Bahadır, Çiğdem Tura; Yılmaz, Merve; Kılıçkan, Elif

doi:10.1111/ijcp.14003

Cited by 8 publications

(7 citation statements)

References 13 publications

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“…The free T3/free T4 ratio is another useful tool that could have helped us differentiate Graves–Basedow disease from other causes of thyrotoxicosis, since a cutoff point >2.96–3.6 has been established, with a sensitivity of 71% and specificity of 88–99%. However, in our case, the free T3 test was not available at that time ( 17 ).…”

Section: Discussionmentioning

confidence: 91%

New-onset thyrotoxicosis in a patient with anaplastic thyroid carcinoma: a diagnostic challenge

Concepción-Zavaleta

Ildefonso-Najarro

Dueñas

et al. 2021

Endocrinology, Diabetes &Amp; Metabolism Case Reports

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Summary Anaplastic thyroid cancer (ATC) is the type of thyroid cancer that has the worst prognosis. It usually presents as a rapidly growing cervical mass that generates compressive symptoms. Its association with thyrotoxicosis is rare. A 76-year-old woman, with no contributory history, presented with a 3-month course of fast-growing cervical tumor, associated with tenderness, cough, and weight loss. Physical examination revealed goiter, localized erythema, and a painful and stone tumor dependent on the right thyroid lobe. Due to the malignant findings of the thyroid ultrasound, the patient underwent a thyroid core needle biopsy, which indicated ATC. Laboratory tests revealed leukocytosis, decreased thyroid-stimulating hormone, elevated free thyroxine (fT4), and increased thyroperoxidase (TPO) antibodies. At the beginning, we considered that the etiology of thyrotoxicosis was secondary to subacute thyroiditis (SAT) after SARS-CoV-2 infection, due to the immunochromatography result and chest tomography findings. The result of markedly elevated TPO antibodies left this etiology more remote. Therefore, we suspected Graves’ disease as an etiology; however, thyroid histopathology and ultrasound did not show compatible findings. Therefore, we suspect that the main etiology of thyrotoxicosis in the patient was the destruction of the thyroid follicles caused by a rapid invasion of malignant cells, which is responsible for the consequent release of preformed thyroid hormone. ATC is a rare endocrine neoplasm with high mortality; it may be associated with thyrotoxicosis, whose etiology can be varied; therefore, differential diagnosis is important for proper management. Learning points Anaplastic thyroid cancer is the thyroid cancer with the worst prognosis and the highest mortality. The association of anaplastic thyroid cancer with thyrotoxicosis is rare, and a differential diagnosis is necessary to provide adequate treatment. Due to the current pandemic, in patients with thyrotoxicosis, it is important to rule out SARS-CoV-2 as an etiology. Anaplastic thyroid cancer, due to its aggressive behavior and rapid growth, can destroy thyroid follicular cells, generating preformed thyroid hormone release, being responsible for thyrotoxicosis.

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Section: Discussionmentioning

confidence: 91%

New-onset thyrotoxicosis in a patient with anaplastic thyroid carcinoma: a diagnostic challenge

Concepción-Zavaleta

Ildefonso-Najarro

Dueñas

et al. 2021

Endocrinology, Diabetes &Amp; Metabolism Case Reports

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“…Additionally, we have examined RLs for FT3/FT4 ratio as useful parameter to detect thyroid disfunction (35)(36)(37)(38). Some authors have pointed out that this ratio is positively correlated with TSH within the reference range of thyroid function in adults (36).…”

Section: Discussionmentioning

confidence: 99%

Indirect estimation of reference intervals for thyroid parameters using advia centaur XP analyzer

Mirjanic-Azaric¹,

Milinković²,

Bogavac-Stanojević³

et al. 2022

J Med Biochemistry

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Background: The aim of this study was to determine the reference intervals (RIs) for thyroid stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3) and FT3/FT4 ratio using indirect methods. Methods: We analysed 1256 results TSH, FT4 and FT3 collected from a laboratory information system between 2017 and 2021. All measurements were performed on a Siemens ADVIA Centaur XP analyser using the chemiluminescent immunoassay. We calculated the values of the 2.5th and 97.5th percentiles as recommended by the IFCC (CLSI C28-A3). Results: The RIs derived for TSH, FT4, FT3 and FT3/FT4 ratio were 0.34-4.10 mIU/L, 11.3-20.6 pmol/L, 3.5-6.32 pmol/L and 0.21-0.47, respectively. We found a significant difference between calculated RIs for the TSH and FT4 and those recommended by the manufacturer. Also, FT3 values were significantly higher in the group younger than 30 years relative to the fourth decade (5.26 vs. 5.02, p=0.005), the fifth decade (5.26 vs. 4.94, p=0.001), the sixth decade (5.26 vs. 4.87, p˂0.001), the seventh decade (5.26 vs. 4.79, p˂0.001) and the group older than 70 years old (5.26 vs. 4.55, p˂0.001). Likewise, we found for TSH values and FT3 / FT4 ratio a significant difference (p <0.001) between different age groups. Conclusions: The establishing RIs for the population of the Republic of Srpska were significantly differed from the recommended RIs by the manufacturer for TSH and FT4. Our results encourage other laboratories to develop their own RIs for thyroid parameters by applying CLSI recommendations.

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“…She had displayed prolonged thyrotoxicosis for 2 years before hospitalization; her clinical course was not typical for destructive thyroiditis, such as subacute thyroiditis and painless thyroiditis. In addition, the FT3/FT4 ratio is lower in destructive thyroiditis than in Graves’ disease, and several studies have shown that the optimal FT3/FT4 ratio cut-off value is 2.8–3.0 [ 5 , 6 ]. In the present case, the FT3/FT4 ratio was elevated at the time of the first diagnosis of overt thyrotoxicosis.…”

Section: Discussionmentioning

confidence: 99%

Thyroid crisis caused by metastatic thyroid cancer: an autopsy case report

et al. 2021

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Background Thyroid crisis is a life-threatening condition in thyrotoxic patients. Although differentiated thyroid cancer is one of the causes of hyperthyroidism, reports on thyroid crisis caused by thyroid cancer are quite limited. Here, we describe a case of thyroid crisis caused by metastatic thyroid cancer. Case presentation A 91-year-old woman was admitted to our hospital because of loss of appetite. Two years prior to this hospitalization, she presented with subclinical thyrotoxicosis and was diagnosed with histologically unidentified thyroid cancer with multiple metastases, and she refused aggressive medical interventions. On admission, she exhibited extreme thyrotoxicosis, and the presence of fever, severe tachycardia, impaired consciousness, and heart failure revealed the presence of thyroid crisis. All thyroid autoantibodies were negative. Multidisciplinary conservative treatment was initiated; however, she died on the fifth day after admission. Autopsy revealed the presence of primary anaplastic thyroid carcinoma and multiple metastatic foci arising from follicular thyroid carcinoma. Both primary and metastatic follicular thyroid carcinoma likely induced thyrotoxicosis, which could have been exacerbated by anaplastic thyroid carcinoma. Conclusions Even though the trigger of thyroid crisis in this patient is not clear, the aggravated progression of her clinical course suggests that careful monitoring of thyroid hormones and appropriate intervention are essential for patients with thyroid cancer.

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Free triiodothyronine to free thyroxine ratio in the differential diagnosis of thyrotoxicosis and hyperthyroidism: A retrospective study

Cited by 8 publications

References 13 publications

New-onset thyrotoxicosis in a patient with anaplastic thyroid carcinoma: a diagnostic challenge

New-onset thyrotoxicosis in a patient with anaplastic thyroid carcinoma: a diagnostic challenge

Indirect estimation of reference intervals for thyroid parameters using advia centaur XP analyzer

Thyroid crisis caused by metastatic thyroid cancer: an autopsy case report

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