Determinants of serum T4 and T3 at the time of diagnosis in nosological types of thyrotoxicosis: a population-based study

OBJECTIVE

To characterize thyroid hormone levels at the time of diagnosis in the nosological types of thyrotoxicosis diagnosed in the population and to analyze determinants for serum thyroxine (T4) and tri-iodothyronine (T3).

DESIGN

Population-based study of thyrotoxicosis at disease onset.

METHODS

In the period 1997-2000, we prospectively identified all patients diagnosed with incident primary overt thyrotoxicosis in a Danish population cohort and classified patients into ten well-defined nosological types of disease (n=1082). Untreated levels of serum T3, T4, and T3:T4 ratio were compared and related to sex, age, level of iodine deficiency, smoking status, alcohol intake, iodine supplement use, co-morbidity, and TSH receptor antibodies (TRAbs) in multivariate models.

RESULTS

Graves' disease (GD) patients had much higher levels of T3 and higher T3:T4 ratio at diagnosis compared with other thyrotoxic patients, but with a profound negative association between hormone levels and age. In GD, patients diagnosed in the area with more severe iodine deficiency had lower levels of T3 and T4. TRAb-negative GD patients had biochemically mild thyrotoxicosis. Higher age was also associated with lower degree of biochemical thyrotoxicosis in nodular toxic goiter. We found no association between serum T3 and T4 and sex, smoking habits, iodine supplements, alcohol intake, or co-morbidity in any type of thyrotoxicosis.

CONCLUSIONS

The study gives new insight into the hormonal presentation of thyrotoxicosis and showed that young age, positive TRAb levels, but also residency in the area with higher iodine intake was positively associated with biochemical disruption in GD.

A report of three cases of jaundice with thyrotoxicosis

BACKGROUND

Jaundice and hepatic dysfunction have been reported in patients with thyrotoxicosis and could be due to different mechanisms.

OBJECTIVE

To describe three cases of jaundice occurring in patients with thyrotoxicosis and to illustrate the importance of early institution of thionamides when indicated.

METHODS

We present the clinical and laboratory features of three patients presenting within a year with thyrotoxicosis and jaundice and whose clinical conditions improved remarkably following treatment with thionamides. In addition, current literature on the subject is reviewed and summarised.

RESULTS

The three patients presented with goitre and jaundice. None of the patients had received blood products, undergone scarification markings or experienced any previous episode of jaundice. Thyroid function tests in the three patients were consistent with a diagnosis of thyrotoxicosis. Liver function tests showed elevated bilirubin and transaminases. All patients improved remarkably following treatment with thionamides.

CONCLUSION

It is important to rule out thyrotoxicosis in patients with jaundice of unknown cause and consider early use of thionamides for treatment of the thyrotoxicosis, if confirmed.

[Clinical case of the month. Thyrotoxic periodic paralysis. Report of a case in a Somalian male]

We report the case of a man hospitalized for tetraparesis related with hypokalemia due to a potassium shift from the extracellular to the intracellular compartment revealing a hyperthyroidism. We will discuss different physiopathological hypotheses giving relating periodic paralysis and hyperthyroidism. Correction of hypokalemia combined with a synthetic antithyroid agent and a beta blocking drug allowed complete motor fonctional recovery.

[Amiodarone treatment and thyroid disorders]

Amiodarone is a benzofuranic iodine-rich antiarrhythmic drug used in the treatment of severe tachyarrhythmias, especially ventricular. Drug causes many adverse effects including thyroid disorders in 14-18% of patients: amiodarone induced thyrotoxicosis type I and type II (AIT I, AIT II) and amiodarone induced hypothyroidism (AIH). AIT occurs more frequently in geographical areas with low iodine intake, whereas AIH is more frequent in iodine-sufficient areas. AIH may appear both in normal thyroid gland and Hashimoto's disease. AIT I occurs most often on the basis of Greave's disease or goiter. In contrast to AIT, AIH does not cause difficulties with diagnosis and treatment. In order to differentiate between AIT I and AIT II such methods as USG, CFDS, RAIU, MIBI and IL-6 are used. Increased vascularization showed in CFDS, increased MIBI uptake in scintigraphy, increased 131I uptake in RAIU in some cases are typical for AIT I. In opposition to AIT I, all this parameters are decreased in AIT II and it is possible that the level of serum IL-6 is increased. However, the usefulness of IL-6 is controversial. After diagnosis discontinuation of amiodarone should be taken into consideration. In addition, AIT I is preferably treated with methimazole and potassium perchlorate. AIT II is treated with glucocorticoids. In the case of unclear diagnosis and mixed types of AIT the combination of all foregoing drugs should be instituted. If the case is refractory, thyreidectomy should be taken into consideration, especially if a patient suffers from left ventricular systolic dysfunction. RIT--radioiodine therapy is also possible.

Prevalence of thyrotoxicosis, antithyroid medication use, and complications among pregnant women in the United States

BACKGROUND

Population-based estimates of the prevalence of thyrotoxicosis (TTX), the frequency of antithyroid drug (ATD) use, and risk of adverse events in pregnant women and their infants are lacking. Therefore, our objective was to obtain epidemiologic estimates of these parameters within a large population-based sample of pregnant women with TTX.

METHODS

A retrospective claims analysis was performed from the MarketScan Commercial Claims and Encounters health insurance database for the period 2005-2009. Women aged 15-44 years, enrolled for at least 2 years, and who had a pregnancy during the study period were included. Diagnosis of TTX was based on International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes using narrow (TTX-1=ICD 242.0) and broad (TTX-2=ICD 242.0 or 242.9) definitions. ATD use was based on prescriptions filled for propylthiouracil (PTU) or methimazole (MMI). Adverse events in mothers and infants were determined from the ICD-9-CM diagnosis codes recorded on submitted claims.

RESULTS

The database contained 904,497 eligible women. The average yearly prevalence per 1000 pregnant women was 2.46 for TTX-1 and 5.88 for TTX-2. Thirty-nine percent used ATD at any time during the study period. Compared to women without a TTX diagnosis, there was more than a twofold increase for liver disease among women with TTX (odds ratio [OR]=2.08, p<0.001) and a 13% increased risk for congenital anomalies (OR=1.13, p=0.014), but no association was observed with ATD use. The rates of congenital defects (per 1000 infants) associated with ATD use were 55.6 for MMI, 72.1 for PTU, and 65.8 for untreated women with TTX, compared to 58.8 among women without TTX.

CONCLUSIONS

There was some indication of an elevated risk of liver disease and congenital anomalies in women with TTX, but the risk did not appear to be related to the ATD use. There seems to be a higher pregnancy termination rate for women with TTX on MMI, which likely reflects elective pregnancy terminations.

Thyroid function and prevalence of anti-thyroperoxidase (TPO) and anti-thyroglobulin (Tg) antibodies in outpatients hospital setting in an area with sufficient iodine intake: influences of age and sex

In order to examine the prevalence of thyroid disease in a hospital outpatient setting, in an area of sufficient iodine intake, serum levels of TSH, T4, T3, anti-Tg and anti-TPO antibodies were examined in 909 individuals with an age range of 12.4 to 88.5 years, participating in a checkup outpatient setting. The study was conducted in Henry Dynant Hospital located in the metropolitan area of Athens, Greece, during a 2 year period. Hormonal parameters were determined by chemiluminescence immunoassay. Overt thyrotoxicosis was found in 4.95% of the total population and subclinical thyrotoxicosis in 5.5%. Overt hypothyroidism was found in 1.43% and subclinical hypothyroidism in 4.51%. In male population, overt thyrotoxicosis was found in 4.4 % and subclinical thyrotoxicosis was also found in 4.4%. On the other hand, overt hypothyroidism was found in 1.4% and subclinical hypothyroidism was found in 3.7% in males. In female population, overt thyrotoxicosis was found in 5.2% whereas subclinical thyrotoxicosis was found in 6.0%. Overt hypothyroidism was found in 1.5% and subclinical hypothyroidism was found in 4,9% in females. Positive anti-TPO antibodies were detected more often (30.4%) than anti-Tg (15.4%) in the tested population. The positivity in both anti-TPO and anti-Tg antibodies was correlated with abnormally high TSH concentrations after the age of 50 years, especially in female population. In conclusion distinct profile of thyroid hormonal parameters was observed in inhabitants in the metropolitan area of Athens, with overt thyrotoxicosis strikingly overcome overt hypothyroidism while subclinical forms of each dysfunction also exhibit analogous results.

Thyrotoxic periodic paralysis with Graves' disease leading to the discovery of a hidden nonclassic 11β hydroxylase deficiency

11β hydroxylase deficiency (OHD) is one of the main causes of congenital adrenal hyperplasia. There have been only a few reported cases of nonclassic 11β OHD, a milder form of the disease. It is difficult to detect occult nonclassic 11β OHD because patients present with no or mild symptoms. We herein present a case of thyrotoxic periodic paralysis (TPP) with Graves' disease leading to the discovery of a hidden nonclassic 11β OHD. In this case, increased levels of thyroid hormone seem to have induced symptoms of occult nonclassic 11β OHD and aggravated TPP.

Recurrent gestational transient thyrotoxicosis presenting as hyperemesis

A 28-year-old G2P1 Thai woman presented with severe nausea and vomiting at 12 weeks' gestation. The initial diagnosis was hyperemesis gravidarum. She was clinically euthyroid. Physical examination revealed no thyroid gland enlargement. The serum thyroid stimulating hormone was suppressed while the free thyroxine level was elevated. This patient had a history of hyperthyroidism during her first pregnancy. An anti-thyroid drug was initiated at 16 weeks' gestation and continued throughout her pregnancy. Follow-up thyroid function tests and thyroid antibodies after her first and second gestation were normal. The diagnosis of recurrent gestational thyrotoxicosis was established. There was no need of antithyroid drug treatment in this case. No adverse pregnancy outcomes were reported.

Peak systolic velocity of superior thyroid artery for the differential diagnosis of thyrotoxicosis

AIM

The 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.

METHODS

A 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.

RESULTS

STA-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.

CONCLUSIONS

STA-PSV is a feasible supplement alternative of RAIU for differentiating the causes of thyrotoxicosis.

Hyperthyroidism in pregnancy

PURPOSE OF REVIEW

Successful outcome in pregnancy hyperthyroidism depends on the cause, interpretation of laboratory tests, and careful use of antithyroid drug (ATD) therapy. Planning of a pregnancy in a woman with active or past history of Graves' hyperthyroidism is mandatory in order to avoid complications.

RECENT FINDINGS

Fetal health may be affected by three factors: poor control of maternal hyperthyroidism, titer of maternal TRAb, and inappropriate use of ATD. Careful assessment of thyroid function through pregnancy and evaluation of fetal development by ultrasonography is the cornerstone for a successful outcome. In a subgroup of women previously treated with ablation therapy, those whose serum TSRAb titers remained elevated, are at risk of having a fetus/neonate with Graves' hyperthyroidism. Use of ATD during lactation is well tolerated, if recommended guidelines are followed.

SUMMARY

Women during their childbearing age with active Graves' hyperthyroidism should plan their pregnancy. Causes of hyperthyroidism in pregnancy include Graves' disease or autonomous adenoma, and transient gestational thyrotoxicosis as a consequence of excessive production of human chroionic gonadotropin by the placenta. Careful interpretation of thyroid function tests and frequent adjustment of ATD is of utmost importance in the outcome of pregnancy. Graves' hyperthyroidism may relapse early in pregnancy or at the end of the first year postpartum.

A young man presenting with paralysis after vigorous exercise

Thyrotoxic periodic paralysis (TPP) is a rare metabolic disorder characterised by muscular weakness and paralysis in predisposed thyrotoxic patients. Although patients with TPP are almost uniformly men of Asian descent, cases have been reported in Caucasian and other ethnic populations. The rapid increase in ethnic diversity in Western and European nations has led to increase in TPP reports, where it was once considered exceedingly rare. Correcting the hypokalaemic and hyperthyroid state tends to reverse the paralysis. However, failure to recognise the condition may lead to delay in diagnosis and serious consequences including respiratory failure and death. We describe a young man who was diagnosed with hyperthyroidism who presented with acute paralysis. The clinical characteristics, pathophysiology and management of TTP are reviewed.

Evaluating and managing patients with thyrotoxicosis

BACKGROUND

Thyrotoxicosis is common in the Australian community and is frequently encountered in general practice. Graves disease, toxic multinodular goitre, toxic adenoma and thyroiditis account for most presentations of thyrotoxicosis.

OBJECTIVE

This article outlines the clinical presentation and evaluation of a patient with thyrotoxicosis. Management of Graves disease, the most frequent cause of thyrotoxicosis, is discussed in further detail.

DISCUSSION

The classic clinical manifestations of thyrotoxicosis are often easily recognised by general practitioners. However, the presenting symptoms of thyrotoxicosis are varied, with atypical presentations common in the elderly. Following biochemical confirmation of thyrotoxicosis, a radionuclide thyroid scan is the most useful investigation in diagnosing the underlying cause. The selection of treatment differs according to the cause of thyrotoxicosis and the wishes of the individual patient. The preferred treatment for Graves disease is usually antithyroid drug therapy, almost always carbimazole. The primary treatment of a toxic multinodular goitre or toxic adenoma is usually radioactive iodine therapy. Specific therapy is usually not warranted in cases of thyroiditis, however, treatment directed at symptoms may be required. Referral to an endocrinologist is recommended if thyroiditis is unlikely or has been excluded.

Thyrotoxic periodic paralysis associated with transient thyrotoxicosis due to painless thyroiditis

Thyrotoxic periodic paralysis (TPP) is a rare manifestation of hyperthyroidism characterized by muscle weakness and hypokalemia. All ethnicities can be affected, but TPP typically presents in men of Asian descent. The most common cause of TPP in thyrotoxicosis is Graves' disease. However, TPP can occur with any form of thyrotoxicosis. Up to our knowledge, very few cases ever reported the relationship between TPP and painless thyroiditis. We herein report a 25-yr-old Korean man who suffered from flaccid paralysis of the lower extremities and numbness of hands. The patient was subsequently diagnosed as having TPP associated with transient thyrotoxicosis due to painless thyroiditis. The paralytic attack did not recur after improving the thyroid function. Therefore, it is necessary that early diagnosis of TPP due to transient thyrotoxicosis is made to administer definite treatment and prevent recurrent paralysis.

Myasthenia gravis associated with thymoma and toxic multinodular goiter. A case report

Adequate antithyroid drug treatment or surgery usually generates remission of myasthenia gravis (MG) in patients with thymus hyperplasia associated with Graves' hyperthyroidism. The case of a 46-year-old woman diagnosed with MG based on the clinical picture, anticholinesterase drug test and positive electromyography (EMG) is presented. The cervico-thoracic computer tomography revealed a compressive nodular goiter and normal antero-superior mediastinum and led to the diagnosis of MG secondary to the hyperthyroidism. An uneventful total thyroidectomy was performed, but postoperatively the MG symptoms worsened. TC99m tetrofosmin scintigraphy revealed an area of hyperfixation in the antero-inferior mediastinum, suggestive for thymoma, as confirmed by a repeated thoracic CT scan. Following a longitudinal sternotomy, a well incapsulated tumor of approximately 6/5 cm located in the antero-inferior mediastinum was found and an extensive thymomectomy was performed. The postoperative course was uneventful and the patient was discharged 9 days later with complete remission of myasthenia. The pathology report of the specimen revealed a mixt thymoma or AB thymoma after Muller-Hermelink and WHO classification, with invasive capsular foci corresponding to Masaoka II stadium. In conclusion, scintigraphy proved to be useful in the diagnosis and decision making of a thymoma.

Thyrotoxicosis

Hyperthyroidism describes the sustained increase in thyroid hormone biosynthesis and secretion by a thyroid gland with increased metabolism. Although the use of radioiodine scanning serves as a useful surrogate that may help characterize the cause of thyrotoxicosis, it only indirectly addresses the underlying physiologic mechanism driving the increase in serum thyroid hormones. In this article, thyrotoxic states are divided into increased or decreased thyroid metabolic function. In addition to the diagnosis, clinical presentation, and treatment of the various causes of hyperthyroidism, a section on functional imaging and appropriate laboratory testing is included.

Coronary artery spasm due to thyrotoxicosis

A 50-year-old lady presented with chest pain, tremor, weight loss and intermittent ST elevation in her ECG associated with elevated markers of myocardial injury. She was diagnosed with Graves' disease and coronary angiogram showed normal coronary arteries. It was felt coronary artery spasm secondary to thyrotoxicosis was the cause for her ECG changes and pain. She was successfully treated with diltiazem, metoprolol and carbimazole. This case highlights the importance of considering hyperthyroidism in the diagnosis of chest pain with normal coronary arteries.

A case of painless thyroiditis in a very early stage of pregnancy

We report a case of painless thyroiditis detected during the first trimester of pregnancy. A 29-year-old Japanese woman was hospitalized because of thyrotoxicosis and she was confirmed to be pregnant. The gestational age was 4 weeks. Blood examinations revealed negative TSH receptor antibodies, however, we started potassium iodide because we were unable to rule out Graves' disease. Thyroid hormone levels were normalized in 3 weeks and remained low even after discontinuation of medication. She received replacement therapy with levothyroxine sodium hydrate till 3 months after delivery. Painless thyroiditis can be one of the differential diagnoses of thyrotoxicosis in a very early stage of pregnancy.

Graves' disease complicated by ventricular fibrillation in three men who were smokers

BACKGROUND

Thyrotoxicosis is known to be associated with sinus tachycardia and supraventricular tachyarrhythmias, but rarely with ventricular fibrillation (Vf), which has only occurred in some patients with hypokalemic periodic paralysis or ischemic heart disease.

PATIENT FINDINGS

We present three men who were transferred to our hospital with Graves' disease who developed idiopathic Vf. None of them had hypokalemic periodic paralysis or ischemic heart disease but all were smokers. None of other patients with thyrotoxicosis (587 females and 155 males) who were seen at our hospital, in the period during which the three men were seen, had idiopathic Vf. In our three men with thyrotoxicosis and idiopathic Vf, there was no identifiable underlying heart disease. One of the three patients died of hypoxic encephalopathy. The other two men did not have recurrent Vf after their thyroid function normalized.

SUMMARY

These cases and a review of similar cases in the literature imply that improving thyrotoxicosis seems to be effective for treating idiopathic Vf in some patients.

CONCLUSIONS

Our findings suggest that thyroid hormone excess might play a direct role in the development of Vf in susceptible individuals. Our experience with these three patients suggests that smoking men with thyrotoxicosis likely have an increased risk for Vf, even if they do not have other predisposing factors.

Primary thyroid lymphoma with elevated free thyroxine level

Primary thyroid lymphoma (PTL) is a rare form of thyroid cancer that is known to be associated with Hashimoto thyroiditis. This association is supported by the presence of elevated titres of both antithyroglobulin and antimicrosomal antibodies in up to 95 percent of patients with PTL. Most patients with PTL present with a rapidly enlarging neck mass and compressive symptoms. The majority of thyroid cancer patients have normal levels of thyroid hormones; they are rarely hyperthyroid, with no obvious clinical features of thyrotoxicosis. We describe a patient who presented with minimal clinical features of thyrotoxicosis despite having markedly elevated serum free thyroxine and suppressed serum thyroid-stimulating hormone levels.