Hypothyroidism associated with positive results of the perchlorate discharge test in elderly patients

Environmental perchlorate, thiocyanate, and nitrate exposures and bone mineral density: a national cross-sectional study in the US adults

Associations of perchlorate, thiocyanate, and nitrate exposures with bone mineral density (BMD) in adults have not previously been studied. This study aimed to estimate the associations of individual and concurrent exposure of the three chemicals with adult BMD. Based on National Health and Nutrition Examination Survey (NHANES, 2011-2018), 1618 non-pregnant adults (age ≥ 20 years and 47.0% female) were included in this study. Survey-weighted linear regression models were used to estimate individual urinary perchlorate, thiocyanate, and nitrate concentrations with lumbar spine BMD and total BMD in adults. Then, weighted quantile sum (WQS) regression and Bayesian kernel machine regression (BKMR) models were conducted to evaluate associations of co-occurrence of the three chemicals with adult BMD. In all participants, nitrate exposure was inversely associated with lumbar spine BMD (β =  - 0.054, 95%CI: - 0.097, - 0.010). In stratification analyses, significant inverse associations were observed in female and participants older than 40 years old. In WQS regressions, significant negative associations of the weighted sum of the three chemicals with total and lumbar spine BMD (β =  - 0.014, 95%CI: - 0.021, - 0.007; β =  - 0.011, 95%CI: - 0.019, - 0.004, respectively) were found, and the dominant contributor was nitrate. In the BKMR models, non-linear dose-response associations of nitrate exposure with lumbar spine and total BMD were observed. These findings suggested that environmental perchlorate, thiocyanate, and nitrate exposure may reduce adult BMD and nitrate is the main contributor.

Subclinical hypothyroidism

PURPOSE OF REVIEW

Mild or subclinical hypothyroidism is characterized by normal serum free thyroxine concentrations with elevated serum thyroid-stimulating hormone concentrations. Subclinical hypothyroidism is relatively prevalent in the general population, especially among women and the elderly. The main cause of subclinical hypothyroidism is autoimmune chronic thyroiditis. The present report reviews the most important and recent studies on subclinical hypothyroidism, and discusses the most controversial aspects of this topic.

RECENT FINDINGS

Several studies have demonstrated that subclinical hypothyroidism may affect both diastolic and systolic cardiac function. It may also worsen many risk factors for cardiovascular disease, including hypertension, abnormal endothelial function, and elevated low-density lipoprotein cholesterol concentrations. Furthermore, a growing body of evidence suggests that subclinical hypothyroidism may cause symptoms or progress to symptomatic overt hypothyroidism.

SUMMARY

Prompt treatment of subclinical hypothyroidism in pregnant women is mandatory to decrease risks for pregnancy complications and impaired cognitive development in offspring. Children with subclinical hypothyroidism should be treated to prevent growth retardation. Whether nonpregnant adult patients with subclinical hypothyroidism should be treated, and at what thyroid-stimulating hormone values, is debatable.

Comparison of MRI findings with traditional criteria in diagnosis of Pendred syndrome

Pendred syndrome, defined as the constellation of goiter, sensori-neural hearing loss, and positive perchlorate discharge test, is the most frequent cause of congenital deafness. Newly introduced diagnostic approaches to the disease are rather expensive and complicated, therefore we evaluated the value of MRI as the sole, or adjunctive diagnostic approach, and compared it with the traditional ones. Presuming the classic triad as the gold standard, we compared MRI findings in six such defined patients with six cases having goiter, hearing loss, and normal perchlorate discharge test. Our results indicated that MRI was 83.6% sensitive and 66.7% specific in patients fulfilling all three criteria (complete), while in the 'partial' group the sensitivity and specificity were 66.7% and 100% respectively. In conclusion, MRI, although impressive as an adjunctive diagnostic tool, may not replace the holistic approach, and the latter may be more convenient, cheaper, and still more accurate. However in 'partial' cases with equivocal findings, and in relatives of the patients, MRI may be a valuable diagnostic adjunct.

Clinical, biochemical and therapeutical aspects of amiodarone-induced hypothyroidism (AIH) in geriatric patients with cardiac arrhythmias

The clinical features and the laboratory aspects of the amiodarone-induced hypothyroidism (AIH) in the elderly as well as the effects of amiodarone treatment in aged AIH people have not yet been well clarified. In the present paper, we evaluated 18 subjects of both sexes (7 females, 11 males), aged 65-83 years, affected by AIH, recruited in Central Tuscany, Italy. The patients were divided in two subsets on the basis of thyroid stimulating hormone (TSH) values: mild (TSH < 20 mU/l; Group A, n=11) and severe (TSH > 20 mU/l; Group B, n=7) hypothyroid patients. On the basis of clinical features, hypothyroidism was diagnosed only in two patients (out of Group B). Concerning the hormonal pattern, we found that free tetraiodothyronine (fT4) levels were significantly lower than the normal range only in Group B subjects; TSH and thyroglobulin were higher than normal in both groups; free triiodothyronine (fT3) were always in the normal range. Thyroid autoantibodies were found positive only in one patient out of Group A and in two patients out of Group B. In 5/18 patients T4 substitutive therapy was rapidly assigned, because of severe degree of hypothyroidism. In the remaining 13/18 patients, we evaluated the clinical behavior of AIH. After additional cardiac evaluation, amiodarone was withdrawn in 5/13 patients: during follow-up period (4-10 months) four patients became quickly euthyroid while one worsened. In 8/13 patients, amiodarone treatment had to be carried on; during follow-up (2-48 months), four patients remained mildly hypothyroid, while other four patients became severely hypothyroid. In conclusion, in amiodarone treated elderly people, diagnosis of hypothyroidism is reliable only on the basis of high values of TSH; clinical features and fT3 serum levels never enable diagnosis.

Perchlorate clinical pharmacology and human health: a review

Potassium perchlorate has been used at various times during the last 50 years to treat hyperthyroidism. Since World War II ammonium perchlorate has been used as a propellant for rockets. In 1997, the assay sensitivity for perchlorate in water was improved from 0.4 mg/L (ppm) to 4 microg/L (ppb). As a result, public water supplies in Southern California were found to contain perchlorate ions in the range of 5 to 8 ppb, and those in Southern Nevada were found to contain 5 to 24 ppb. Research programs have been developed to assess the safety or risk from these exposures and to assist state and regulatory agencies in setting a reasonable safe level for perchlorate in drinking water. This report reviews the evidence on the human health effects of perchlorate exposure. Perchlorate is a competitive inhibitor of iodine uptake. All of its pharmacologic effects at current therapeutic levels or lower are associated with inhibition of the sodium-iodide symporter (NIS) on the thyroid follicular cell membrane. A review of the medical and occupational studies has been undertaken to identify perchlorate exposure levels at which thyroid hormone levels may be reduced or thyrotropin levels increased. This exposure level may begin in the 35 to 100 mg/d range. Volunteer studies have been designed to determine the exposure levels at which perchlorate begins to affect iodine uptake in humans. Such effects may begin at levels of approximately 1 mg/d. Environmental studies have assessed the thyroidal health of newborns and adults at current environmental exposures to perchlorate and have concluded that the present levels appear to be safe. Whereas additional studies are underway both in laboratory animals and in the field, it appears that a safe level can be established for perchlorate in water and that regulatory agencies and others are now trying to determine that level.

Screening for thyroid diseases in an iodine sufficient area with sensitive thyrotrophin assays, and serum thyroid autoantibody and urinary iodide determinations

OBJECTIVE

The present study was designed to investigate the prevalence of thyroid dysfunction and its relation to thyroid autoantibodies and urine iodide concentration in apparently healthy people residing in Sapporo, a city of northern Japan, where the iodine intake is high.

DESIGN AND SUBJECTS

Serum TSH and thyroid autoantibodies, and urine iodide were measured in 4110 people (2931 men and 1179 women) (age 45.6 +/- 10.3 years (mean +/- SD)) who were recruited at the hospital for medical examinations.

RESULTS

The thyroid autoantibodies were positive in 6.4% of males and 13.8% of females with an age-related increase. Of the people with positive antibodies, 87.2% had normal TSH values (0.15-5.0 mU/l) as measured by a sensitive assay. The prevalence of unsuspected hyperthyroidism as defined by suppressed TSH values was 0.61%, of which 64% was diagnosed as Graves' disease based on positive thyrotrophin receptor antibody results. The prevalence of unsuspected hypothyroidism, as evidenced by supranormal TSH, was 0.68% for males and 3.13% for females with an age-related increase. Of those with hypothyroidism, 45.5% were autoantibody positive. The overall prevalence of Hashimoto's thyroiditis was 13.11% for females and 6.15% for males. The urine iodide levels of hypothyroidism with a positive autoantibody of 38.5 (17.7-83.9) mumol/l and a negative autoantibody of 34.9 (17.9-67.9) mumol/l were both significantly higher than that of normal subjects (26.9 (14.6-49.6) mumol/l) (P < 0.01). When iodine intake was restricted for 6-8 weeks for hypothyroid subjects, the elevated TSH and thyroglobulin and low free T4 levels were reversed in the autoantibody negative but not in the positive group.

CONCLUSIONS

This study provides further information on the prevalence of thyroid dysfunction and autoimmune thyroid diseases in an iodine sufficient area. In addition, it suggests that more than half of the patients with unsuspected hypothyroidism were negative for autoantibodies and that the excessive iodine intake may be involved in causing latent hypothyroidism.

Thyroid stimulating hormone elevation without antithyroid antibody elevation in nursing home patients

OBJECTIVES

To investigate the relationship between antithyroid antibody elevation and thyrotropin (TSH) elevation.

SETTING

Large state veterans home.

METHODS

Seven hundred seventy-six residents were screened for TSH elevation. Seventy-two residents with TSH elevation and no history of thyroid disease or recent iodine exposure later had determinations of antithyroglobulin and antimicrosomal antibodies. The relationship between TSH levels and antibody titers was explored.

RESULTS

Eleven percent of the residents had TSH elevation. Thirty-two percent of men and 64% of women with TSH elevation had elevation of antithyroid antibodies. Those residents with the highest antithyroid antibody titers had significantly greater TSH elevation.

CONCLUSION

Previous investigators have found similar percentages of individuals with TSH elevation who lack antithyroid antibody elevation. We hypothesize that TSH elevation without elevated antibody titers may be the result of a previously described involutional histologic lesion of the thyroid.

Thyroid disease in the elderly

As people in our society live longer, it is important for clinicians to know more about problems commonly seen in the elderly. Thyroid problems are especially important to understand because they do occur with rather high frequency, and their mode of presentation is frequently different from those seen in younger patients. The thyroid gland does undergo certain age-related changes in anatomy and physiology, but overall the thyroid is able to produce a normal amount of thyroid hormone throughout the years. Hypothyroidism is frequently difficult to diagnose in the elderly, because many of the symptoms of hypothyroidism can easily be confused with symptoms of aging. When hypothyroidism is looked for in large population studies of elderly patients, the incidence varies from 1% to as high as 17%, with women being more commonly affected than men, and subclinical hypothyroidism being more common than overt hypothyroidism. Virtually all cases of hypothyroidism are due to autoimmune thyroid disease, with most patients having measurable titers of thyroid autoantibodies. The therapy of hypothyroidism is done with extreme caution, as older patients are frequently very sensitive to the effects of excess thyroid hormone. In addition, the metabolism of thyroid hormone slows down with age, making the full replacement dose much less in an older patient than in a younger one. Hyperthyroidism is also quite common, occurring in from 0.5% to 3% of all elderly patients. The presentation is frequently atypical, as patients often lack the hyperdynamic symptomatology and instead have a more sedated, apathetic presentation. Weight loss and cardiac symptoms frequently predominate, and the presence of a goiter is frequently absent, making the diagnosis less obvious than in a younger patient. Therapy is usually radioactive iodine, after an adequate course of antithyroid drugs, to render the patient euthyroid. Thyroid nodules do occur with increasing frequency in the elderly, but most of them are not malignant. Fine-needle aspiration for cytology is very helpful in determining which patients should be referred for surgery. Well-differentiated cancers do predominate, but their course is frequently less predictable than in younger patients. Lymphoma of the thyroid and undifferentiated cancers do occur with increasing frequency in the elderly. Multinodular goiter, usually of longstanding, is frequently seen in elderly patients, and thyroid hormone suppressive therapy not only is not indicated but may contribute to exogenous hyperthyroidism.

Thyroid hormone use: trends in the United States from 1960 through 1988

Thyroid hormone preparations comprised over 1% of all prescriptions filled by retail pharmacies during 1988 in the conterminous United States, i.e., the 48 contiguous states. Their large market share gives the patterns of their use substantial public health importance. This article describes prescription thyroid hormone use in the United States from 1960 through 1988, using pharmaceutical marketing research data collected from panels of retail pharmacies and office-based physicians. Although the use of natural products has declined by over 50% since 1960, about one fourth of all thyroid hormone prescriptions were for natural preparations as recently as 1988. Per capita thyroid mentions (i.e., patient-physician contacts during which a thyroid agent of any kind was recommended, prescribed, dispensed, administered, ordered to be given by a hospital, or given as a sample) doubled during this period among those over 59 years old. Per capita mentions for synthetic thyroid products increased fourfold and tenfold among men and women in this age group, respectively. Use for weight loss, despite the label's boxed warning indicating it to be ineffective and potentially dangerous, has diminished but persists. Obesity was second only to hypothyroidism among the diagnoses underlying thyroid product mentions.

Unilateral multinodular toxic goiter: scintiscan mimicking solitary toxic nodule

A 58-year-old man presented with hyperthyroidism. By palpation, the left lobe of the thyroid was diffusely enlarged, and the right lobe was normal. Radioactive iodide scintiscan demonstrated homogeneous uptake that was localized to the enlarged left lobe, with near total suppression of uptake on the right. TSH stimulation led to clear visualization of a normal appearing right lobe, findings most consistent with an autonomously functioning solitary nodule on the left. Left hemithyroidectomy cured the hyperthyroidism. However, no single dominant nodule was found in the left lobe. Rather, there was diffuse thyroidal hyperplasia of the micronodular variety, consistent with multinodular toxic goiter. Thus, in this patient with a usually diffuse form of thyroid disease, the autonomously functioning hyperactive follicles were localized predominantly to one thyroid lobe. This variant expands the clinical spectrum of multinodular toxic goiter, and further emphasizes the extent of asymmetry in the distribution of hyperactive follicles than can occur in this disorder.