Comparison of serum thyrotrophin concentrations determined by a third generation assay in patients with various types of overt and subclinical thyrotoxicosis

Kasagi, Kanji; Kousaka, T; Murakami, Takashi; Iwata, Masahiro; Alam, Mohammad; Konishi, Junji

doi:10.1046/j.1365-2265.1999.00632.x

Cited by 20 publications

(20 citation statements)

References 18 publications

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“…The zinc concentration in erythrocytes has recently been reported to be a useful measure for making a differential diagnosis [4], but such measurements are not routinely performed. A highly sensitive thirdgeneration TSH assay has also been reported to be useful [14], but a clear overlap in values for the two types of thyrotoxicosis limits its practical use.…”

Section: Discussionmentioning

confidence: 99%

Ratio of Serum Free Triiodothyronine to Free Thyroxine in Graves' Hyperthyroidism and Thyrotoxicosis Caused by Painless Thyroiditis

Noh

Momotani²,

Fukada

et al. 2005

Endocr J

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Abstract. The serum T 3 to T 4 ratio is a useful indicator for differentiating destruction-induced thyrotoxicosis from Graves' thyrotoxicosis. However, the usefulness of the serum free T 3 (FT 3 ) to free T 4 (FT 4 ) ratio is controversial. We therefore systematically evaluated the usefulness of this ratio, based on measurements made using two widely available commercial kits in two hospitals. Eighty-two untreated patients with thyrotoxicosis (48 patients with Graves' disease and 34 patients with painless thyroiditis) were examined in Kuma Hospital, and 218 patients (126 with Graves' disease and 92 with painless thyroiditis) and 66 normal controls were examined in Ito Hospital. The FT 3 and FT 4 values, as well as the FT 3 / FT 4 ratios, were significantly higher in the patients with Graves' disease than in those with painless thyroiditis in both hospitals, but considerable overlap between the two disorders was observed. Receiver operating characteristic (ROC) curves for the FT 3 and FT 4 values and the FT 3 /FT 4 ratios of patients with Graves' disease and those with painless thyroiditis seen in both hospitals were prepared, and the area under the curves (AUC), the cut-off points for discriminating Graves' disease from painless thyroiditis, the sensitivity, and the specificity were calculated. AUC and sensitivity of the FT 3 /FT 4 ratio were smaller than those of FT 3 and FT 4 in both hospitals. The patients treated at Ito hospital were then divided into 4 groups according to their FT 4 levels (A: £2.3, B: >2.3~£3.9, C: 3.9~£5.4, D: >5.4 ng/dl), and the AUC, cutoff points, sensitivity, and specificity of the FT 3 /FT 4 ratios were calculated. The AUC and sensitivity of each group increased with the FT 4 levels (AUC: 57.8%, 72.1%, 91.1%, and 93.4%, respectively; sensitivity: 62.6%, 50.0%, 77.8%, and 97.0%, respectively). The means ± SE of the FT 3 /FT 4 ratio in the Graves' disease groups were 3.1 ± 0.22, 3.1 ± 0.09, 3.2 ± 0.06, and 3.1 ± 0.07, respectively, versus 2.9 ± 0.1, 2.6 ± 0.07, 2.5 ± 0.12, and 2.3 ± 0.15, respectively, in the painless thyroiditis groups. In the painless thyroiditis patients, the difference in the FT 3 /FT 4 ratio between group A and group D was significant (p<0.05). Thus, the FT 3 /FT 4 ratio in patients with Graves' disease likely remains unchanged as the FT 4 level rises, whereas this ratio decreases as the FT 4 level rises in patients with painless thyroiditis. In conclusion, the FT 3 /FT 4 ratios of patients with painless thyroiditis overlapped with those of patients with Graves' disease. However, this ratio was useful for differentiating between these two disorders when the FT 4 values were high.

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Section: Discussionmentioning

confidence: 99%

Ratio of Serum Free Triiodothyronine to Free Thyroxine in Graves' Hyperthyroidism and Thyrotoxicosis Caused by Painless Thyroiditis

Noh

Momotani²,

Fukada

et al. 2005

Endocr J

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“…Hyperthyroidism is a common disease of older cats and has many similarities to human toxic nodular goiter including insidious onset, presence of hyperplastic or adenomatous nodular changes in the thyroid, and peak incidence in old age. Hyperthyroidism in human patients is usually diagnosed by demonstration of subnormal thyroid stimulating hormone (TSH) concentrations in conjunction with increased free thyroxine (fT4) concentrations . A syndrome of subclinical hyperthyroidism has been identified in human patients who have within‐reference‐range fT4 and tri‐iodothyronine (T3) concentrations but TSH concentrations below the reference range …”

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confidence: 99%

Evaluation of Predictors for the Diagnosis of Hyperthyroidism in Cats

Wakeling

Elliott

Syme

2011

Veterinary Internal Medicne

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Background: In humans, subclinical hyperthyroidism is diagnosed when serum thyroid hormone concentrations are within the reference range but thyroid stimulating hormone (TSH) concentration is subnormal. In a previous study, a higher prevalence of thyroid nodular disease was found in euthyroid geriatric cats with undetectable TSH (<0.03 ng/mL) compared to those with detectable TSH concentrations, suggesting subclinical hyperthyroidism might also exist in cats.Hypothesis: Euthyroid cats with undetectable TSH concentrations have subclinical hyperthyroidism and may subsequently develop overt signs of hyperthyroidism.Animals: One-hundred four client-owned cats. Methods: In this prospective cohort study, euthyroid geriatric (!9 years) cats were recruited during routine health checks. Plasma biochemistry was performed at baseline and every 6 months thereafter. Total thyroxine and TSH concentrations were determined annually. Short-term follow-up data (within 14 months of recruitment) were used to detect variables at entry that were predictive of the diagnosis of hyperthyroidism, using univariable analysis followed by multivariable logistic regression analysis. Log rank analysis was used to test the association of initial TSH concentration with diagnosis of hyperthyroidism during the total available follow-up.Results and Conclusions: Median (range) follow-up was 26 (0-54) months and annual incidence of hyperthyroidism during the study was 7.4%. Cats that became hyperthyroid within 14 months had higher ALKP activity (P = 0.02) and higher prevalence of goiter (P = .03) at baseline than controls. Cats with undetectable TSH at baseline (29/104; 28%) were significantly (P < .001) more likely to be diagnosed with hyperthyroidism. However, not all cats with undetectable TSH became hyperthyroid during the study.

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“…Doubtless, this is the basis upon which the low but detectable TSH concentrations in our patients were reported to be`probable non-thyroidal illness' by our hospital laboratory, the outpatient rather than inpatient source of the samples perhaps not being readily apparent to the reporter. Of particular interest in the context of this current study are the observations of Kasagi et al 10 that the combination of a normal serum free T 4 and an incompletely suppressed serum TSH concentration, as measured by a third-generation assay, was seen exclusively in patients with euthyroid ophthalmic Graves' disease and autonomously functioning thyroid nodules.…”

Section: Discussionmentioning

confidence: 91%

Low but detectable serum thyroid-stimulating hormone concentrations in ambulant subjects not receiving thyroxine

et al. 2003

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Comparison of serum thyrotrophin concentrations determined by a third generation assay in patients with various types of overt and subclinical thyrotoxicosis

Abstract: The third-generation TSH assay is useful for the differential diagnosis of various types of thyrotoxicosis, especially between Graves' disease and destructive thyroiditis.

Cited by 20 publications

References 18 publications

Ratio of Serum Free Triiodothyronine to Free Thyroxine in Graves' Hyperthyroidism and Thyrotoxicosis Caused by Painless Thyroiditis

Ratio of Serum Free Triiodothyronine to Free Thyroxine in Graves' Hyperthyroidism and Thyrotoxicosis Caused by Painless Thyroiditis

Evaluation of Predictors for the Diagnosis of Hyperthyroidism in Cats

Low but detectable serum thyroid-stimulating hormone concentrations in ambulant subjects not receiving thyroxine

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