Thyroid disease

Subclinical thyroid dysfunction symptoms in older adults: cross-sectional study in UK primary care

BACKGROUND

Subclinical thyroid dysfunction - abnormal serum thyrotrophin (thyroid-stimulating hormone; TSH) concentrations with normal free thyroxine (FT4) is common in older people. It remains unclear whether individuals with subclinical serum status experience an increased symptom profile.

AIM

To compare the prevalence of those symptoms typically associated with overt thyroid dysfunction in older individuals with a subclinical and euthyroid serum profile.

DESIGN AND SETTING

Cross-sectional study, nested within the Birmingham Elderly Thyroid Study (BETS); from 19 UK general practices.

METHOD

Adults living in a community setting (aged ≥65 years), without overt thyroid dysfunction or associated treatment, self-reported the presence or absence of 18 symptoms (while serum result naïve). Serum concentrations of TSH and FT4 were measured to establish thyroid status.

RESULTS

A total of 2870 individuals were screened: 2703 (94%) were categorised as euthyroid (normal), 29 (1%) subclinically hyperthyroid, and 138 (5%) subclinically hypothyroid. Symptoms were common in all groups. No significant differences in the prevalence of individual symptoms were observed between the euthyroid and subclinically hypothyroid groups nor in comparison with the subclinically hyperthyroid group. Multivariate logistic regression analysis failed to reveal an association between individual or multiple symptoms and subclinical status.

CONCLUSION

Findings suggest that subclinical thyroid dysfunction does not confer a symptom burden in older individuals and support adherence to guidelines in the non-treatment of subclinical thyroid dysfunction. GPs may use the findings to reassure older people presenting with symptoms that subclinical thyroid dysfunction is an unlikely explanation. The presence of persistently abnormal TSH concentrations may be linked to long-term risks of cardiovascular disease, especially atrial fibrillation, but whether this should prompt treatment and whether such treatment alters vascular outcomes is unknown.

Evaluation of a protocol for hypertonic saline administration in acute euvolemic symptomatic hyponatremia: A prospective observational trial

Context:

Acute symptomatic hyponatremia is a frequent yet poorly studied clinical problem. Aims: To develop a non-weight based protocol for the treatment of acute symptomatic hyponatremia.

Settings and Design:

Observational study in a Multi-disciplinary Intensive Care Unit of an urban tertiary care hospital.

Materials and Methods:

Patients aged >18 years, admitted with euvolemic acute symptomatic severe hyponatremia (defined as serum sodium <120 meq/l with symptoms <24 hours), formed the study population. On confirmation of euvolemic status clinically and by laboratory investigations, patients were administered 100 ml of 3% NaCl over a period of 4 hours irrespective of the weight of the patient, followed by reassessment of serum Na at the end of 4 hours. The volume of hypertonic saline (in ml) required to increase serum Na by 8 meq/l was calculated using the formula: 100 × 8/increment in serum Na observed with 100 ml hypertonic saline. This volume was infused over the next 20 hours. To monitor renal water diuresis which may contribute to overcorrection, the urine specific gravity was monitored every 4 hours for sudden decrease of ≥ 0.010 from the baseline value. Measurement of serum Na was repeated if a fall in the urine specific gravity was observed and subsequently repeated every 4 hours. If no fall occurs in urine specific gravity, serum Na measurement was repeated at 12, 20 and at 24 hours (0 hour being the initiation of 100 ml hypertonic saline). The volume of infusate was adjusted if an excessive increment of serum Na (greater than 3 meq at 8 hours, 4 meq at 12 hours, 5 meq at 16 hours and 6 meq at 20 hours) was observed. Baseline characteristics were compared using chi-square test and Mann–Whitney U test.

Results:

58 patients formed the study cohort. The mean age was 58 years. The mean serum Na on admission was 114 meq/l. Administration of 100 ml hypertonic saline resulted in a mean increase in serum Na of 2 meq/l. The mean increase in serum Na over 24 hours was 9 meq/l and mean volume of hypertonic saline required for a serum Na increment of 8 meq/l was 600 ml.

Conclusions:

The non-weight based protocol with monitoring for water diuresis is reasonably an effective strategy in the treatment of acute euvolemic symptomatic hyponatremia.

Prevalence of hyperthyroidism after exposure during childhood or adolescence to radioiodines from the chornobyl nuclear accident: dose-response results from the Ukrainian-American Cohort Study

Relatively few data are available on the prevalence of hyperthyroidism (TSH concentrations of <0.3 mIU/liter, with normal or elevated concentrations of free T4) in individuals exposed to radioiodines at low levels. The accident at the Chornobyl (Chernobyl) nuclear plant in Ukraine on April 26, 1986 exposed large numbers of residents to radioactive fallout, principally to iodine-131 ((131)I) (mean and median doses  =  0.6 Gy and 0.2 Gy). We investigated the relationship between (131)I and prevalent hyperthyroidism among 11,853 individuals exposed as children or adolescents in Ukraine who underwent an in-depth, standardized thyroid gland screening examination 12-14 years later. Radioactivity measurements taken shortly after the accident were available for all subjects and were used to estimate individual thyroid doses. We identified 76 cases of hyperthyroidism (11 overt, 65 subclinical). Using logistic regression, we tested a variety of continuous risk models and conducted categorical analyses for all subjects combined and for females (53 cases, n  =  5,767) and males (23 cases, n  =  6,086) separately but found no convincing evidence of a dose-response relationship between (131)I and hyperthyroidism. There was some suggestion of elevated risk among females in an analysis based on a dichotomous dose model with a threshold of 0.5 Gy chosen empirically (OR  =  1.86, P  =  0.06), but the statistical significance level was reduced (P  =  0.13) in a formal analysis with an estimated threshold. In summary, after a thorough exploration of the data, we found no statistically significant dose-response relationship between individual (131)I thyroid doses and prevalent hyperthyroidism.

Once weekly thyroxine treatment as a strategy to treat non-compliance

Hypothyroidism is a common disorder, which is mainly treated in primary rather than secondary care. Once daily thyroxine replacement restores euthyroidism in most patients; some patients, however, remain hypothyroid despite adequate thyroxine replacement. Non-compliance is the most common cause of lack of response to thyroxine treatment. We describe two cases of primary hypothyroidism in which daily thyroxine treatment did not restore biochemical euthyroidism but once weekly thyroxine treatment was successful. In addition we review the evidence and discuss the differential diagnosis of lack of response to thyroxine treatment. Once weekly thyroxine treatment can be a safe, well-tolerated, and effective therapy for patients with non-compliance.

Dermatologic aspects of thyroid disease

Thyroid disorders commonly have dermatologic manifestations. The purpose of the present chapter is to review and emphasize potential clinical dermatologic findings that can occur with Graves' disease, hypothyroidism and thyroid cancer. In autoimmune diseases such as Graves' disease and Hashimoto's thyroiditis the skin manifestations may be related to either thyroid hormone levels themselves or to the associated T and/or B cell abnormalities. Thyroid cancer may be associated with various syndromes that could have significant skin manifestations.

Radiotherapy for primary thyroid cancer as a risk factor for second primary cancers

Although radiation is considered a risk factor for thyroid cancer, the potential relationship between radiation therapy and the risk of second primary cancer among patients with first primary thyroid cancer has not been evaluated. We identified 26,639 patients with first primary thyroid cancer in the Surveillance, Epidemiology, and End Results (SEER) database from 1973 to 2000. Information on radiation therapy as well as second primary cancers was recorded in SEER. The proportional hazards model was utilized to estimate adjusted risk ratios (RRs) and their 95% confidence intervals (CIs) to assess the potential association between radiation therapy for thyroid cancer and the risk of second primary cancers. With 270,674.33 person-years of follow-up, 1,896 (7.1%) of the 26,639 patients with first primary thyroid cancer developed second primary cancers. Among the second primaries, 35 occurred in the thyroid. No obvious association was observed between radiation therapy and the overall risk of second primary cancer after ten years of follow-up (RR=1.07, 95% CI=0.88-1.30). However, an increased risk was seen for several cancers, including upper digestive system cancers (RR=1.66, 95% CI=1.07-2.57) and myeloid malignancies (RR=3.26, 95% CI=1.39-7.67). Radiation therapy was associated with reduced second cancer risks for thyroid cancer (RR=0.18, 95% CI=0.04-0.76). Beam radiation might be important to the digestive system, radioactive implants might be associated with the male genital system, radioisotopes might have an effect on myeloid malignancies, and combined beam radiation with radioactive implants or radioisotopes might be related to the increased risk of respiratory system cancers. This study suggests that radiation therapy for patients with first primary thyroid cancer might be associated with an increased risk of developing a second primary cancer in the upper digestive system and second primary myeloid malignancies. Radiation therapy for adult patients with thyroid cancer might be associated with a reduced risk of second primary thyroid cancer.

Tissue distribution and thyroid hormone regulation of Pept1 and Pept2 mRNA in rodents

Peptide transporters (Pept) have essential physiological functions and also transport various drugs. Information regarding tissue distribution and gene regulation of Pept in rodents is limited. The present study investigated the distribution of Pept1 and Pept2 mRNA in 19 tissues of male and female Sprague-Dawley rats and C57BL/6 mice, as well as thyroid hormone regulation of renal Pept expression in male rats, using the branched DNA signal amplification assay. Pept1 mRNA was not only highly expressed in small intestine, but also detectable in gonads of both species, kidney of rats, and large intestine of mice. Pept2 mRNA was the highest in kidney, followed by brain and lung. The present study offers the first evidence of considerable Pept2 mRNA expression in pituitary and reproductive organs (testis, prostate, ovary, and uterus). Interestingly, Pept2 mRNA expression in mouse prostate appeared to be much higher than that in rat prostate. Thyroidectomy increased Pept1 and Pept2 mRNA in male rat kidney; such increases were abolished by thyroid hormone replacement.