Prevention, screening and therapy of thyroid diseases and their cost-effectiveness

A Clinical Debate: What Is the Therapeutic Choice for Recurrent Graves' Hyperthyroidism?

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Alteration in intrinsic and extrinsic functional connectivity of resting state networks associated with subclinical hypothyroid

Subclinical hypothyroidism (SCH) is characterized by mild elevation of thyroid stimulating hormone (TSH) (range 5-10 μIU/ml) and normal free triiodothyronine (FT3) and free thyroxine (FT4). The cognitive function impairment is well known in thyroid disorders such as hypothyroidism and hyperthyroidism, but little is known about deficits in brain functions in SCH subjects. Also, whether hormone-replacement treatment is necessary or not in SCH subjects is still debatable. In order to have an insight into the cognition of SCH subjects, intrinsic and extrinsic functional connectivity (FC) of the resting state networks (RSNs) was studied. For resting state data analysis we used an unbiased, data-driven approach based on Independent Component Analysis (ICA) and dual-regression that can emphasize widespread changes in FC without restricting to a set of predefined seeds. 28 SCH subjects and 28 matched healthy controls (HC) participated in the study. RSN analysis showed significantly decreased intrinsic FC in somato-motor network (SMN) and right fronto-parietal attention network (RAN) and increased intrinsic FC in default mode network (DMN) in SCH subjects as compared to control subjects. The reduced intrinsic FC in the SMN and RAN suggests neuro-cognitive alterations in SCH subjects in the corresponding functions which were also evident from the deficit in the neuropsychological performance of the SCH subjects on behavioural tests such as digit span, delayed recall, visual retention, recognition, Bender Gestalt and Mini-Mental State Examination (MMSE). We also found a significant reduction in extrinsic network FC between DMN and RAN; SMN and posterior default mode network (PDMN); and increased extrinsic FC between SMN and anterior default mode network (ADMN) in SCH subjects as compared to controls. An altered extrinsic FC in SCH suggests functional reorganization in response to neurological disruption. The partial correlation analysis between intrinsic and extrinsic RSNs FC and neuropsychological performances as well as clinical indices give interesting insights into brain-behavior relationship in SCH subjects. This article is protected by copyright. All rights reserved.

[Benign thyroid nodule or thyroid cancer?]

Thyroid nodular disease is highly frequent and affects 20-23% of the adult population in Germany. Differential diagnosis of thyroid nodules is directed at exclusion of thyroid autonomy and thyroid cancer. In addition, large nodules/nodular goiters may cause oesophageal and/or tracheal compression. Besides the patient's history and clinical examination, laboratory investigations (TSH-level, calcitonin screening), functional (scintiscan) and morphological imaging (ultrasound, in rare cases also CT without contrast media and MRI), as well as fine needle aspiration biopsy are useful tools in the differential diagnosis. In the past years, major advances have been made in the understanding of the molecular pathogenesis of thyroid tumors. This has led to the possibility of a molecular classification of thyroid tumors and may have prognostic as well as therapeutic impact.

Thyroid function and cognitive decline in the MRC Cognitive Function and Ageing Study

Hypothyroidism and subclinical hyperthyroidism have both been associated with cognitive impairment and dementia. The association between thyroid stimulating hormone (TSH), free thyroid hormone or thyroxine (FT4) levels and cognition was investigated at baseline and after a 2 year follow-up in 1047 participants over 64 years of age, without physical frailty or severe cognitive impairment at baseline. Results indicated that high log transformed TSH levels were associated with lower MMSE performance (B=-0.24 (S.E.=0.09), 95% CI=-0.41 to -0.07) at baseline, independent of FT4, age, sex, education and mood, and, in separate analyses, cardiovascular (risk) factors. Importantly, half of all hypothyroid cases were untreated and unaware of having this disorder. In analyses which excluded cases with thyroid disorders, stroke and those suspected of possible dementia/cognitive impairment (MMSE less than 25) or psychiatric mood disorders at baseline, high-normal FT4 levels were associated with worse MMSE performance and a greater risk for a drop of at least 4 points on the MMSE after 2 years (per pmol/l O.R.=1.13, 95% C.I.=1.03-1.22). In conclusion, elderly patients with cognitive impairment should always be assessed for hypothyroidism. It is unclear why high normal FT4 levels were independently associated with accelerated cognitive decline in those without overt thyroid disease. Other studies found that thyroxine can generate oxidative stress and damage neurons. Treatment with thyroxine in those without thyroid disease (as is sometimes done in anti-ageing clinics) is thus not recommended on the basis of these data and the optimal therapeutic level in the elderly may be lower than is assumed.

Age-dependent cutoff values in screening newborns for hypothyroidism

OBJECTIVES

We wanted to develop age-related reference (cutoff) values and an algorithm to identify babies at low, moderate, and high risk for hypothyroidism of any cause. We used thyroid-stimulating hormone (TSH) as the primary tool, and thyroxine (T4) as part of a confirmatory test. Our data permitted us to estimate cutoff values for newborns at <24 h, 24 to 47 h, 48 to 71 h, 72 to 95 h, and > or =96 h after birth.

METHODS

We used a time-resolved fluoroimmunoassay method for TSH and T4 with the AutoDELPHIA instrument (Perkin-Elmer Life Sciences, Turku, Finland). TESTING ALGORITHM: We developed a conservative algorithm for TSH and T4 testing. In the initial screening, we used a > or =20 microIU/ml cutoff for TSH to identify those babies of any age who required confirmatory testing on a repunched filter paper blood specimen.

RESULTS

In 161,244 newborns tested during 2002, we found 8,035 babies with TSH values > or =20 microIU/ml. Graphs of the values for TSH vs. age in hours revealed the possibility of using more than one cutoff value. The general finding was that the cutoff values decreased with increasing age of the newborn.

CONCLUSIONS

Based on our findings, we conclude that testing babies who are <24 h old is not recommended and should only be performed if no other specimen is available. A high TSH in babies <24 h old is unreliable for screening newborns for hypothyroidism. We routinely stipulate that the infant be at least 48 h old for TSH and T4 testing. If not, the cutoff value must be set to a higher value to prevent an excessive number of false-positive results; however, this increases the chance of missing a truly hypothyroid baby. We designated newborns as being at "low" (LR), "moderate" (MR), or at "high" risk (HR) for hypothyroidism. The TSH test continues to be a screening test; and follow-up quantitative testing and clinical evaluation are needed for all babies identified as being at MR or HR for hypothyroidism.

SETTING

Newborn Screening Laboratory of the Ohio Department of Health, Columbus, Ohio.