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PubMed1995

Caring for survivors of the Chernobyl disaster. What the clinician should know.

The health status of approximately 1 million immigrants in the United States and Israel may have been adversely affected by radiation exposure as a result of the Chernobyl nuclear power plant disaster and cleanup efforts. Many of these immigrants suffer from significant psychological distress, fearing that they have a radiation-induced illness. Based on a review of the literature and our experience from the US National Chernobyl Registry Coordinating Center, we recommend that medical management of these immigrants include routine physical examination, with particular attention to the thyroid gland. Adults should receive regular cancer screening as well as routine blood chemistry tests, thyroid function tests, complete blood cell count, and urinalysis. Children should be examined regularly, with attention to the thyroid and overall body growth. It is reasonable for children to undergo thyroid studies, a complete blood cell count, or neuropsychiatric testing if there is clinical suspicion of a disorder. Given the long latency period for disease induction by radiation exposure, it is still too early to fully assess and draw conclusions concerning the possible health effects of the Chernobyl disaster, and long-term follow-up of all potentially affected individuals is important.

Adult↗
PubMed2002

Nonthyroidal illness syndrome: evaluation of thyroid function in sick patients.

Altered thyroid function tests as a consequence of illness have been recognized for many years, yet the cause and clinical implications remains uncertain. The routine testing of thyroid function in hospitalized patients should be discouraged, as the results are less predictive of primary thyroid disease than in ambulatory patients. Clinicians should be aware of the methods used for thyroid function testing, as the effect of illness on thyroid function varies among the different tests. The most commonly used free T4 assays likely are influenced significantly by nonthyroidal illness. Advances in understanding the basic mechanisms of thyroid hormone metabolism and thyroid hormone action have given insights into the changes in thyroid function tests as a consequence of nonthyroidal illness. In the future, thyroid hormone receptor isoform-specific agonists and antagonists may allow for more specific treatment of select patients with nonthyroidal illness syndrome.

Disease↗
PubMed1999

Congenital hypothyroidism: etiologies, diagnosis, and management.

Congenital hypothyroidism is a common preventable cause of mental retardation. The overall incidence is approximately 1:4000; females are affected about twice as often as males. Approximately 85% of cases are sporadic, while 15% are hereditary. The most common sporadic etiology is thyroid dysgenesis, with ectopic glands more common than aplasia or hypoplasia. While the pathogenesis of dysgenesis is largely unknown, some cases are now discovered to be the result of mutations in the transcription factors PAX-8 and TTF-2. Loss of function mutations in the thyrotropin (TSH) receptor have been demonstrated to cause some familial forms of athyreosis. The most common hereditary etiology is the inborn errors of thyroxine (T4) synthesis. Recent mutations have been described in the genes coding for the sodium/iodide symporter, thyroid peroxidase (TPO), and thyroglobulin. Transplacental passage of a maternal thyrotropin receptor blocking antibody (TRB-Ab) causes a transient form of familial congenital hypothyroidism. The vast majority of infants are now diagnosed after detection through newborn screening programs using a primary T4-backup TSH or primary TSH test. Screening test results must be confirmed by serum thyroid function tests. Thyroid scintigraphy, using 99mTc or 123I, is the most accurate diagnostic test to detect thyroid dysgenesis or one of the inborn errors of T4 synthesis. Thyroid sonography is nearly as accurate, but it may miss some cases of ectopic glands. If maternal antibody-mediated hypothyroidism is suspected, measurement of maternal and/or neonatal TRB-Ab will confirm the diagnosis. The goals of treatment are to raise the serum T4 as rapidly as possible into the normal range, adjust the levothyroxine dose with growth to keep the serum T4 (or free T4) in the upper half of the normal range and the TSH normal, and maintain normal growth and development while avoiding overtreatment. An initial starting dose of 10-15 microg/kg per day is recommended; this dose will decrease on a weight basis over time. Serum T4 (or free T4) and TSH should be monitored every 1-2 months in the first year of life and every 2-3 months in the second and third years.

Congenital Hypothyroidism↗
PubMed1990

Monitoring therapy in patients taking levothyroxine.

PURPOSE: To evaluate the use of thyroid function tests to monitor therapy in patients taking levothyroxine. DATA IDENTIFICATION: Studies published between 1966 and January 1990 were identified through computer searches and references of identified studies. STUDY SELECTION: Studies that included a careful description of the patients under study, well-defined interventions, and a meaningful criterion standard were emphasized. DATA EXTRACTION: Data from different studies were combined to estimate the probability of positive and negative test results in well-defined clinical situations. Informal methods of synthesizing evidence were used when combining data from different studies was not justified. RESULTS: The sensitive thyrotropin (TSH) test is the preferred method to monitor therapy because it agrees with physiologic measures of thyroid hormone effect. Among clinically euthyroid patients who take 100 to 150 micrograms/d of levothyroxine, the probability that the sensitive thyrotropin will be undetectable is close to 50%. These patients are most likely to benefit from testing. Patients who take over 250 micrograms/d are almost certain to have undetectable sensitive thyrotropin levels; in these patients, the dose may be lowered without testing. CONCLUSIONS: Adequate long-term studies are needed to determine the role of biochemical testing in monitoring therapy. Current evidence suggests that the sensitive thyrotropin test should be used to monitor therapy. Clinically euthyroid patients taking lower dosages of levothyroxine are most likely to benefit from testing.

Humans↗
PubMed2000

Investigation of prolonged neonatal jaundice.

UNLABELLED: Jaundice persisting beyond 14 d of age (prolonged jaundice) can be a sign of serious underlying liver disease. Protocols for investigating prolonged jaundice vary in complexity and the yield from screening has not been assessed. In order to address these issues, we carried out a prospective study of term infants referred to our neonatal unit with prolonged jaundice over an 18 mo period. Infants were examined by a paediatrician and had the following investigations: a total and conjugated serum bilirubin, liver function tests, full blood count, packed cell volume, group and Coombs' test, thyroid function tests, glucose-6-phosphate dehydrogenase levels and urine for culture. One-hundred-and-fifty-four infants were referred with prolonged jaundice out of 7,139 live births during the study period. Nine infants were referred to other paediatric specialties. One infant had a conjugated hyperbilirubinaemia, giving an incidence of conjugated hyperbilirubinaemia of 0.14 per 1,000 live births. Diagnoses included: giant cell hepatitis (n = 1), hepatoblastoma (n = 1), trisomy 9p (n = 1), urinary tract infections (n = 2), glucose-6-phosphate dehydrogenase deficiency (n = 3) and failure to regain birthweight (n = 1). CONCLUSIONS: In conclusion, a large number of infants referred to hospital for prolonged jaundice screening had detectable problems. The number of investigations may safely be reduced to: a total and conjugated bilirubin, packed cell volume, glucose-6-phosphate dehydrogenase level (where appropriate), a urine for culture and inspection of a recent stool sample for bile pigmentation. Clinical examination by a paediatrician has a vital role in the screening process.

Bilirubin↗
PubMed2003

Risk factors of thyroid abnormalities in bipolar patients receiving lithium: a case control study.

BACKGROUND: Lithium-induced thyroid abnormalities have been documented in many studies. They may occur despite normal plasma lithium levels. The objectives of this study were: 1) to determine possible relationship between lithium ratio, defined as erythrocyte lithium concentrations divided by plasma lithium concentrations, and thyroid abnormalities in bipolar patients receiving lithium and 2) to find other possible risk factors for developing thyroid abnormalities in the subjects. METHODS: Sixty-eight bipolar patients receiving lithium therapy were enrolled in a cross-sectional evaluation of thyroid function test and thyroid size. Patients were divided into two groups based on their thyroid function tests and thyroid sizes. Erythrocyte and plasma lithium concentrations were determined by atomic absorption spectrometry for each patient. Lithium ratio was then calculated. RESULTS: No significant differences were found between age, positive family history of affective disorder, plasma lithium concentration, erythrocyte lithium concentration, and lithium ratio comparing the two groups. Thyroid abnormalities was significantly higher in women than in men (p < 0.05). CONCLUSIONS: Lithium ratio does not appear to have a predictive role for thyroidal side effects of lithium therapy. Female gender was the main risk factor. We suggest more frequent thyroid evaluation of bipolar women who are treated with lithium.

Adult↗
PubMed1995

The investigation of thyroid function.

The measurement of thyrotropin (TSH) by a third-generation assay (functional sensitivity 0.01-0.02 mU/L) offers the single best test of assessing thyroid status and is more cost effective than measurement of thyroxine (T4) as a first-line test. However, in certain situations, e.g., nonthyroidal illness (NTI), secondary thyroid disease, early treatment of hyperthyroidism, early pregnancy, and heterophilic antibody interference, TSH alone may be misleading, and thyroid hormone measurements are also required. The author's laboratory has found that the measurement of TSH together with free thyroxine (by a nonanalogue method) offers the most speedy and effective first-line strategy for thyroid function testing. Abnormalities in thyroid function tests in euthyroid patients are most likely found in NTI and the elderly. For this reason, thyroid function tests (TFTs) should not be requested in elderly or hospitalized patients unless the presenting complaint is considered to be because of a thyroid problem.

Humans↗
PubMed1978

TSH response pattern to TRH test and optimum time of blood sampling in sporadic euthyroid goitre.

Attempts were made to estimate the response pattern of thyrotrophin (TSH) to thyrotrophin-releasing hormone (TRH) and the optimum time of blood sampling in patients with sporadic euthyroid goitre. Of the 65 subjects studied, 21 served as a reference group and 44 were patients with sporadic euthyroid goitres, divided into diagnostic subgroups according to type of goitre. Patients with a single autonomous thyroid adenoma were excluded. The classification of goitre was based on clinical features, thyroid function tests, thyroid imaging studies using 99mTc pertechnetate uptake, and examination of thyroid specimens originating from selective goitre resection carried out after the laboratory investigations. A standardized i.v. TRH test was performed in all probands and the TSH response was followed for 60 min postinjection. There was a definite trend towards lack of response with increasing nodularity of the thyroid gland. Moreover, no further information concerning the TSH response pattern was achieved by extending the blood sampling period beyond the +20 min limit of the time axis. The study lends support to the view that increasing functional autonomy is a general trend in goitre evolution.

Adult↗
PubMed1999

Plummer's disease with spontaneous progression to hypothyroidism.

A case of Plummer's disease that spontaneously progressed to hypothyroidism is presented. A 49-year-old female visited our hospital because of a 3 kg decrease in body weight during the previous month and a painless nodule in the right anterior area of her neck. A diagnosis of Plummer's disease was made based on the results of thyroid function tests, thyroid scintigrams, and an ultrasonogram, but the patient's disease followed an usual clinical course. About two months later, she gradually developed manifestations of permanent hypothyroidism, and anti-thyroid autoantibodies became positive. In spite of continuous administration of levothyroxine sodium, uptake of 99mTcO4- to the nodule was unchanged or rather increased according to the consecutive thyroid scintigraphies. These results suggested that this case represented an autonomously functioning nodule with underlying silent thyroiditis and Hashimoto's disease.

Autoantibodies↗