[Thyroid dysfunction and pregnancy]. / Dysfonction thyroïdienne et grossesse.

The pregnancy is a state of thyroid hyperstimulation, therefore of changes of thyroid hormone values. Results of thyroid hormone measurement have to be analysed in the context of gestation age. Hyperthyroidism, mostly represented by Graves' disease, requires a multidisciplinary management, owing to possible maternal, foetal and neonatal complications. Treatment with antithyroid drugs, is a compromise between the risk of uncontrolled maternal hyperthyroidism and the risk of iatrogenic foetal hypothyroidism. Evaluation of foetal thyroid function considers the titre of thyrotropin receptor antibodies in the mother's blood, the dose of antithyroid drugs to maintain euthyroidism in the mother, and the signs of foetal hyperthyroidism on ultrasound. Maternal hypothyroidism is associated with foetal and maternal morbidity. Untreated or inappropriately treated, it is associated with poorer performances of offspring in intelligence tests. Thyroid autoimmunity is associated with hypofertility, particularly with spontaneous abortion. Screening for thyroid dysfunction during pregnancy, although not systematic, should have broad indications.

Clinical, hormonal and magnetic resonance imaging (MRI) predictors of transsphenoidal surgery outcome in acromegaly.

OBJECTIVE: Progress in the treatment of acromegaly with drugs is making it necessary to improve the prediction of the outcome of transsphenoidal surgery. DESIGN: We evaluated clinical, hormonal and radiologic predictors based on magnetic resonance imaging (MRI) of surgical outcome in patients with acromegaly. METHODS: This retrospective analysis included 125 consecutive patients investigated for acromegaly in a single endocrine unit since the use of MRI imaging began (1988). Eighty-three of these patients (50 women) underwent transsphenoidal surgery and were investigated before and after surgery in our department. A neuroradiologist unaware of the surgical outcome analyzed the results of pituitary gland MRI investigations. RESULTS: Surgical remission rates were 44%, 43%, 61% and 59% based on mean basal GH concentration under 2.5 microg/l, GH/oral glucose tolerance test (OGTT) of <1 microg/l, GH/OGTT of <2 microg/l or IGF-I concentration normal for age and sex respectively. In univariate logistic regression analysis with IGF-I concentration used as the criterion for cure, young age (P<0.001), high IGF-I concentration before surgery (P<0.01), high basal GH concentration before surgery (P<0.02), and high nadir GH/OGTT before surgery (P=0.03) were predictors of poor outcome. The following results in standardized MRI analysis were associated with a higher probability of not being cured: adenoma greater than 15 mm in diameter (P<0.02), infrasellar extension (P=0.04), suprasellar extension (P<0.005) and invasive adenoma (0.02) according to MRI staging. MRI analysis of the intracavernous extension showed that stages above B2 (possible sinus extension with sign of invasion of the space below the carotid artery) were associated with a lower probability of postoperative normal GH plasma levels (P=0.01). In multivariate analysis, age, preoperative hormonal levels and adenoma size remained the major predictors of surgical outcome. CONCLUSIONS: This report provides the first evidence that detailed MRI analysis of adenoma size, location and potential invasion, together with preoperative clinical and hormonal parameters, can be used for the prediction of hormonal outcome after transsphenoidal surgery for acromegaly.

Abnormal stimulation of the thyrotrophin receptor during gestation.

Pregnancy induces physiological alterations in thyroid function which may make difficult the interpretation of results of thyroid hormone measurement. A state of hyperstimulation of the thyroid gland is common in early pregnancy. In a few cases, thyroid hormone values will deviate from the normal range, which corresponds to the gestational transient thyrotoxicosis. This syndrome is closely associated with hyperemesis gravidarum. The relationship between the two syndromes, demonstrated by epidemiological studies, has been illustrated by an exceptional case of familial recurrent gestational thyrotoxicosis presenting as hyperemesis gravidarum due to hypersensitivity of the thyrotrophin receptor to hCG. However, the exact mechanisms of hyperemesis gravidarum have not yet been identified. Gestational transient thyrotoxicosis has to be distinguished from Graves' disease, because the latter is associated with potential maternal and fetal complications when thyrotoxicosis is not controlled, whereas the former has usually a favourable outcome. The existence of other cases of thyroid hypersensitivity or hCG endowed with abnormal thyrotrophic activity is suspected. They may be identified only by assessment of the thyroid function in cases of hyperemesis gravidarum. The identification of these cases would be helpful to understand the mechanisms of specificity of glycoprotein hormone receptors.