Hyperthyroidism evaluation

Interferon-a causes hypothyroidism in up to 39% of patients being treated for hepatitis C infection. Patients may develop a transient thyroiditis with hyperthyroidism prior to becoming hypothyroid. The hypothyroidism may be transient as well. Asians and patients with preexisting anti-TPOAbs are more likely to develop interferon-induced hypothyroidism. The mechanism of interferon-induced hypothyroidism is not known. If LT4 replacement is initiated, it should be stopped after 6 months to re-evaluate the need for replacement therapy. 

American Association of Clinical Endocrinologists Thyroid Task Force. Evaluation and Treatment of Hyperthyroidism and Hypothyroidism, 2002 www.aace.com/clin/guidelines/hypo hyper.pdf accessed October 30,2005. 

The answer is d. (Hardman, p 1401.) In patients who are suspected of having hyperthyroidism, propranolol can be administered to provide temporary relief of the peripheral manifestations of the disease while the patient is further evaluated. Propranolol suppresses adrenergic symptoms such as tremors and tachycardia it has no effect on the release of thyroid hormones from the gland. 

After therapy (thionamides, RAI, or surgery) for hyperthyroidism has been initiated, patients should be evaluated on a monthly basis until they reach a euthyroid condition. 

John Rosen (419 and 420) claimed that direct analysis (a psychoanalytic-like technique) produced improvement in 37 cases of deteriorated schizophrenia. He defined improvement as the ability to live comfortably outside of an institution, with the achievement of psychological integrity, emotional stability, and character structure such that a patient could withstand as much environmental stress as one who never experienced a psychotic episode. The credibility of this claim, however, was shattered by an independent evaluation of these patients outcome. Five years later, a follow-up of Rosen s group found that 37% had not been initially diagnosed as schizophrenic, but rather as psychoneurotic, manic-depressive, or possibly hyperthyroid (e.g., one patient recovered after her thyroid was removed). The remainder met criteria for schizophrenia, and during the next 10 years, 75% had between two and five subsequent readmissions. Thus, Rosen s initial claims were not substantiated because many did not have schizophrenia, and most of those who did were not able to sustain their improvement. 

Amiodarone blocks the peripheral conversion of thyroxine (T4 ) to triiodothyronine (T3). It is also a potential source of large amounts of inorganic iodine. Amiodarone may result in hypothyroidism or hyperthyroidism. Thyroid function should be evaluated before initiating treatment and should be monitored periodically. Because effects have been described in virtually every organ system, amiodarone treatment should be reevaluated whenever new symptoms develop in a patient, including arrhythmia aggravation. 

Her weight is 136 lb (61.8 kg), an increase of 10 lb (4.5 kg) in the last year. Her thyroid gland is not palpable and her reflexes are delayed. Laboratory findings include a thyroid-stimulating hormone (TSH) level of 14.9 pIU/mL and a free thyroxine level of 8 pmol/L. Evaluate the management of her past history of hyperthyroidism. Identify the available treatment options for control of her current thyroid status. 

Because of reports of severe hyperthyroidism after the introduction of iodized salt in two severely iodine-deficient African counties (Zimbabwe and the Democratic Republic of the Congo), a multicenter study has been conducted in seven countries in the region to evaluate whether the occurrence of iodine-induced hyperthyroidism after the introduction of iodized salt was a generalized phenomenon or corresponded to specific local circumstances in the two affected countries (46). Iodine deficiency had been successfully eliminated in all of the areas investigated and the prevalence of goiter had fallen markedly. However, it was clear that some areas were now exposed to iodine excess as a result of poor monitoring of the quality of iodized salt and of the iodine intake of the population. In these areas, iodine-induced hyperthyroidism occurred only when iodized salt had been recently introduced. 

Bal CS, Kumar A, Pandey RM. A randomized controlled trial to evaluate the adjuvant effect of lithium on radioiodine treatment of hyperthyroidism. Thyroid 2002 12(5) 399-405. 

Several studies have evaluated the effects of excessive iodine intake in humans, and antithyroid antibodies and iodine-induced hypo- and hyperthyroidism have been reported following long-term iodine treatment for endemic goitre (Boyages et al., 1989 Kahaly et al., 1997, 1998). 

Joseph K, Mahlstedt J, Gonneemann R, Herbert K and Welcke U (1980) Early recognition and evaluation of the risk of hyperthyroidism in thyroid autonomy in an endemic goitre area. J Mol Med 4 21-37. 

Perchlorate is a competitive inhibitor of the sodium-iodide symporter (NIS) and has been used in pharmacological doses to treat hyperthyroidism, especially iodine-induced hyperthyroidism. Perchlorate appears to be ubiquitous in the environment, and has been detected in trace amounts in the urine in almost all subjects evaluated both in the United States and Europe. In prospective clinical studies and environmental studies, there is no convincing evidence that environmental perchlorate adversely affects thyroid function. 

Behavioral disorders, including hyperactivity and impaited concentration, are known to be associated with hyperthyroidism and hypothyroidism, respectively. This evidence validated the hypothesis that ADHD might be similarly related to thyroid disease. Nonetheless, the vast majority of the studies carried out to address this issue failed to demonstrate a definite association between ADHD and thyroid function abnormalities, and therefore the effective role of thyroid hormones in the pathogenesis of the disorder became a candidate for reassessment. It must be pointed out however, that most of these studies evaluated thyroid function in schoolchildren or adults, without taking into account any previous thyroid dysfunction suffered either by them or their mothers during gestation. 

Another important group, the National IDD Advisory Committee (NIDDAC) chaired by Professor Chen Zupei, has played a crucial role in the national program. Under the leadership of the MOH, NIDDAC provides scientific and technical guidefines, standards and recommendations. It also provides evidence for poficy development (IDD Newsletter, 1998). Since 1993 NIDDAC has re-evaluated and standardized the measmement of thyroid gland size by palpation and ultrasound standardized urinary iodine testing methods. It has also evaluated the technical aspects and the application of neonatal TSH in IDD monitoring, iodine excess and excessive dietary iodine-induced goiter, and the role of iodized oil in the prevention and control of IDD and iodine-induced hyperthyroidism (Chen, 2002). 

Oversuppression of TSH with levothyroxine may also cause remarkable adverse cardiac effects. In a Framingham study, a cohort of 2007 persons 60 years of age or older who did not have atrial fibrillation at baseline were evaluated in order to determine the frequency of this arrhythmia during a 10-year follow-up period. This study showed that subjects with TSH levels <0.1mU/l presented a three-fold risk of developing atrial fibrillation in relation to subjects with normal TSH values (Sawin et al., 1994). A recent prospective study performed in individuals aged 65 years or older demonstrated that subjects with subclinical hyperthyroidism exhibited a greater incidence of atrial fibrillation compared with those with normal thyroid function (Cappola (S /., 2006). 

TSH test. Measuring the serum TSH has become the screen test of choice for thyroid disease. Primary hypothyroidism produces elevated TSH levels, whereas patients with primary hyperthyroidism (i.e., Graves disease) should have undetectable TSH values. This relationship is true only in individuals with an intact hypothalamic-pituitary-thyroid axis. Patients who present with a normal or detectable TSH level and elevated thyroid hormone concentrations require further evaluation to exclude central causes of hyperthyroidism. 

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