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The thyroid gland is a very rare location of metastasis and the metastatic involvement of the thyroid is mostly asymptomatic. The authors report one of the first cases of pulmonary adenocarcinoma associated with painful metastatic involvement of the thyroid gland. Temporary hyperthyroidism was noted, followed, two months later, by clinically and biologically proven hypothyroidism with positive antithyroglobulin antibodies. The suspect goiter was detected by diffuse hyperfixation on 18-FDG PET Scan and the ultrasonography revealed two hypoechogenic nodules. The fine needle biopsy confirmed the metastatic origin of these nodules. The evolution after five cycles of chemotherapy by cisplatine and docetaxel was marked by a complete regression of the thyroid metastasis and an improvement in the thyroid function.

Objectives: Subclinical hypothyroidism defined by the presence of elevated TSH levels but normal free T4 level is a common situation. Its consequences on health are yet on debate and the interest of a precocious treatment remains surrounded by controversy., Key Points: The relationship between subclinical hypothyroidism and cardiovascular disease has been evaluated by several cross-sectional and longitudinal studies. Subclinical hypothyroidism has direct but subtle effects on the heart function, on the peripheral vascular resistance, and is associated with a mild elevation of LDL-cholesterol levels; all abnormalities may be partly reversed by a thyroxine supplementation. Data of the literature give insufficient evidence as to whether subclinical hypothyroidism is an independent cardiovascular risk factor. However treatment of subjects with TSH levels up or near to 10 mU/l would probably be beneficial in the prevention of cardiovascular disease., Future Prospects: Based on observational and interventional studies there are some arguments on the benefit of euthyroidism restoration only in patients with TSH levels superior to 10 mU/l.

DEFINING THE PROBLEM: Sub-clinical hypothyroidism, defined as a moderate and isolated increase in TSH levels, is a common syndrome and is the first phase of a progressive disease. However its treatment remains controversial. Some anamnestic, clinical and biological (anti-thyroperoxidase antibodies) parameters contribute in identifying the patients most likely to progress towards overt hypothyroidism. WHAT CAN BE EXPECTED OF TREATMENT? Several clinical studies have described cardiovascular, neuromuscular and lipid disorders in these patients, but administration of levothyroxine has provided varying results and does not enable the distinction between a pharmacological-like intrinsic effect of the thyroid hormone and the true benefits imputable to the correction of TSH, in the absence of any large interventional study. More studies are required to better identify the patients who will benefit most from hormone replacement.

Treatment of primary hypothyroidism requires a long-term hormonal therapy with levothyroxine which restores a normal TSH value. In a series of 192 patients followed up for at least 3 years we tried to evaluate the variability of maintenance dosage and to analyse the factors predictive of replacement dosage. The L-T4 dosage varied from one individual to the other, from 0.6 to 3.2 micrograms/kg. The mean maintenance dosage (118 +/- 38 micrograms/day) was similar in men and women weight for weight, but it was higher in subjects aged under 60 and in those with Hashimoto's or congenital hypothyroidism. There is a positive linear relation between the equilibrium dose and the TSH value (n = 0.84; p < 0.001) and a negative relation with the L-T4 concentration (n = 0.71; p < 0.001). The yearly variation of dosage in each individual was small (about 3.5%) and of the same order as the variation of weight. We conclude that the L-T4 maintenance dosage depends on the cause of hypothyroidism, on the importance of biochemical abnormalities and on the patient's age, sex and weight. In practice, however, the necessary dosage is difficult to predict. In the equilibrium phase the need for replacements is remarkably stable. A yearly assay of baseline TSH seems to be sufficient to evaluate the quality of hormonal compensation in the absence of intercurrent events.

Abstract: Objectives: Subclinical hypothyroidism defined by the presence of elevated TSH levels but normal free T4 level is a common situation. Its consequences on health are yet on debate and the interest of a precocious treatment remains surrounded by controversy. Key points: The relationship between subclinical hypothyroidism and cardiovascular disease has been evaluated by several cross-sectional and longitudinal studies. Subclinical hypothyroidism has direct but subtle effects on the heart function, on the peripheral vascular resistance, and is associated with a mild elevation of LDL-cholesterol levels; all abnormalities may be partly reversed by a thyroxine supplementation. Data of the literature give insufficient evidence as to whether subclinical hypothyroidism is an independent cardiovascular risk factor. However treatment of subjects with TSH levels up or near to 10 mU/l would probably be beneficial in the prevention of cardiovascular disease. Future prospects: Based on observational and interventional studies there are some arguments on the benefit of euthyroidism restoration only in patients with TSH levels superior to 10 mU/l. [Copyright &y& Elsevier]