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

Noh, Jaeduk Yoshimura; Momotani, Naoko; Fukada, Shuji; Ito, Koichi; Miyauchi, Akira; Amino, Nobuyuki

doi:10.1507/endocrj.52.537

Cited by 50 publications

(40 citation statements)

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“…A key finding is that PM 2.5 exposure during the third trimester of gestation is inversely associated with TSH levels and the FT 4 /FT 3 ratio in cord blood, but not with thyroid hormones in maternal blood. The FT 4 /FT 3 ratio in cord blood is a useful indicator of how effectively the body is able to convert T 4 into T 3 (Yoshimura Noh et al 2005). In addition, results of the mediation analysis suggested that cord blood FT 4 is a partial mediator of the association between third-trimester pregnancy PM 2.5 exposure and birth weight, assuming the underlying causal assumptions of mediation analysis are valid.…”

Section: Discussionmentioning

confidence: 99%

Fetal Thyroid Function, Birth Weight, and in Utero Exposure to Fine Particle Air Pollution: A Birth Cohort Study

Janssen

Saenen

Roels

et al. 2017

Environ Health Perspect

101

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Background:Thyroid hormones are critical for fetal development and growth. Whether prenatal exposure to fine particle air pollution (≤ 2.5 μm; PM2.5) affects fetal thyroid function and what the impact is on birth weight in normal healthy pregnancies have not been studied yet.Objectives:We studied the impact of third-trimester PM2.5 exposure on fetal and maternal thyroid hormones and their mediating role on birth weight.Methods:We measured the levels of free thyroid hormones (FT3, FT4) and thyroid-stimulating hormone (TSH) in cord blood (n = 499) and maternal blood (n = 431) collected after delivery from mother–child pairs enrolled between February 2010 and June 2014 in the ENVIRONAGE birth cohort with catchment area in the province of Limburg, Belgium.Results:An interquartile range (IQR) increment (8.2 μg/m3) in third-trimester PM2.5 exposure was inversely associated with cord blood TSH levels (–11.6%; 95% CI: –21.8, –0.1) and the FT4/FT3 ratio (–62.7%; 95% CI: –91.6, –33.8). A 10th–90th percentile decrease in cord blood FT4 levels was associated with a 56 g decrease in mean birth weight (95% CI: –90, –23). Assuming causality, we estimated that cord blood FT4 mediated 21% (–19 g; 95% CI: –37, –1) of the estimated effect of an IQR increment in third-trimester PM2.5 exposure on birth weight. Third-trimester PM2.5 exposure was inversely but not significantly associated with maternal blood FT4 levels collected 1 day after delivery (–4.0%, 95% CI: –8.0, 0.2 for an IQR increment in third-trimester PM2.5).Conclusions:In our study population of normal healthy pregnancies, third-trimester exposure to PM2.5 air pollution was associated with differences in fetal thyroid hormone levels that may contribute to reduced birth weight. Additional research is needed to confirm our findings in other populations and to evaluate potential consequences later in life.Citation:Janssen BG, Saenen ND, Roels HA, Madhloum N, Gyselaers W, Lefebvre W, Penders J, Vanpoucke C, Vrijens K, Nawrot TS. 2017. Fetal thyroid function, birth weight, and in utero exposure to fine particle air pollution: a birth cohort study. Environ Health Perspect 125:699–705; http://dx.doi.org/10.1289/EHP508

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Section: Discussionmentioning

confidence: 99%

Fetal Thyroid Function, Birth Weight, and in Utero Exposure to Fine Particle Air Pollution: A Birth Cohort Study

Janssen

Saenen

Roels

et al. 2017

Environ Health Perspect

101

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“…Sometimes it can be quite challenging, due to the possibility of painless thyroiditis and early-stage atypical GD [9]. Generally, the following methods are commonly used in the differentiation of transient thyrotoxicosis and GD: thyroid technetium 99 scan, RAIU assay, T3/T4 ratio [10], [11], serum markers such as total activity of alkaline phosphatase [12] and TRAb [4], [13], [14]. Serological assays such as FT3/FT4 ratio [10], [11] and alkaline phosphatase activity had limited values in the differential diagnosis [10], [12].…”

Section: Discussionmentioning

confidence: 99%

Peak Systolic Velocity of Superior Thyroid Artery for the Differential Diagnosis of Thyrotoxicosis

Zhao

Chen

et al. 2012

PLoS ONE

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AimThe differentiation of destruction-induced thyrotoxicosis and Graves’ disease (GD) is of great importance for selection of proper therapy. Radioactive iodine uptake (RAIU) is the gold standard for differentiating these two conditions but its application has remained somewhat limited. Thyroid color Doppler flow sonography (CDFS) is a potential alternative of RAIU but more supporting evidence is warranted. In the present study, a standard operative procedure was developed to measure the mean peak systolic velocity of superior thyroid artery (STA-PSV) and evaluate its role in the differential diagnosis of thyrotoxicosis.MethodsA total of 135 patients with untreated thyrotoxicosis were enrolled into one retrospective study (GD, n = 103; thyroiditis, n = 32) and another prospective study recruited 169 patients (GD, n = 118; thyroiditis, n = 51). Thirty normal controls were also enrolled. Thyroid function, anti-TSH-receptor antibody (TRAb), RAIU, CFDS of thyroid and STA-PSV were performed for each patient. Receiver operator curve (ROC) was used to evaluate the diagnostic value of STA-PSV in a retrospective study so as to seek the optimal cutoff point. Then the cutoff point value was used to validate its diagnostic value in a prospective study and in another thyrotoxicosis population.ResultsSTA-PSV of GD was significantly higher than that of thyroiditis in both retrospective and prospective studies. The area under the ROC curve of mean STA-PSV was 0.8799 and 0.9447 in the retrospective and prospective studies respectively. If a mean STA-PSV cutoff point of 50.5 cm/s was set from the retrospective analysis for the prospective study, the sensitivity and specificity in distinguishing GD from thyroiditis were 81.04% and 96.08% respectively. Mean STA-PSV and TRAb had similar area under ROC. The coefficients of variation in STA-PSV measurement were lower than 10% for the euthyroid, thyroiditis and GD groups.ConclusionsSTA-PSV is a feasible supplement alternative of RAIU for differentiating the causes of thyrotoxicosis.

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“…Instead, the ultrasonographic findings were considered to be enough to support a diagnosis of silent thyroiditis. Additionally, in our case, the calculated ratio of free T4 to free T3 was 2.70, which was lower than its cutoff point [15]. This may indicate the possibility of destructive thyrotoxicosis rather than Graves’ disease, for which no causal treatment was required.…”

Section: Case Reportmentioning

confidence: 64%

Pitting type of pretibial edema in a patient with silent thyroiditis successfully treated by angiotensin II receptor blockade

et al. 2014

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Patient: Female, 56Final Diagnosis: Thyroiditis – silentSymptoms: Palpitations • pretibial pitting edema • short of breath • sweatingMedication: —Clinical Procedure: —Specialty: Endocrinology and MetabolicObjective:Unknown etiologyBackground:Hyper- or hypothyroidism sometimes causes pretibial myxedema characterized by non-pitting infiltration of a proteinaceous ground substance. However, in those patients, the “pitting” type of pretibial edema as a result of increased sodium and fluid retention or vascular hyper-permeability rarely occurs, except in cases complicated by heart failures due to severe cardiomyopathy or pulmonary hypertension.Case Report:A 56-year-old woman developed bilateral pretibial pitting edema, followed by occasional sweating, palpitations, and shortness of breath, which persisted for more than 2 months. The diagnosis of hyperthyroidism due to silent thyroiditis was supported by elevated levels of free thyroxine (T4) and triiodothyronine (T3), with a marked decrease in thyroid-stimulating hormone (TSH), and the negative results for TSH receptor antibodies with typical findings of destructive thyrotoxicosis. Despite her “pitting” type of pretibial edema, a chest radio-graph demonstrated the absence of cardiomyopathy or congestive heart failure. Oral administration of angiotensin II receptor blocker (ARB) was initiated for her systolic hypertension, with a relatively higher elevation of plasma renin activity compared to that of the aldosterone level. Although the symptoms characteristic to hyperthyroidism, such as increased sweating, palpitations and shortness of breath, slowly improved with a spontaneous resolution of the disease, ARB quickly resolved the pretibial pitting edema shortly after the administration..Conclusions:In this case, increased activity of the renin-angiotensin-aldosterone system stimulated by thyroid hormone was likely responsible for the patient’s pitting type of edema. The pharmacological blockade of the renin-angiotensin-aldosterone system was thought to be effective for the quick resolution of the symptom.

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

Cited by 50 publications

References 19 publications

Fetal Thyroid Function, Birth Weight, and in Utero Exposure to Fine Particle Air Pollution: A Birth Cohort Study

Fetal Thyroid Function, Birth Weight, and in Utero Exposure to Fine Particle Air Pollution: A Birth Cohort Study

Peak Systolic Velocity of Superior Thyroid Artery for the Differential Diagnosis of Thyrotoxicosis

Pitting type of pretibial edema in a patient with silent thyroiditis successfully treated by angiotensin II receptor blockade

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