[Obesity, energy regulation and thyroid function: is borderline elevated TSH-level the cause or secondary phenomenon of obesity]. / Adipositas, Stoffwechsel und Schilddrüse. Ist der grenzwertig hohe TSH-Spiegel Ursache oder Sekundärphänomen der Adipositas?

Several population-based studies have shown a significant association between TSH-level and BMI (body mass index). About 30% of the rest energy expenditure are regulated by thyroid hormones, which generated the hypothesis that thyroid hormone substitution with TSH-titration into the lower reference levels may prevent body weight gain. The opposite effect of thyroid hormones is appetite stimulation, which may be responsible for body weight gain in case of substitutive medication. The association between TSH and BMI has become a complex topic in the light of the endocrine activity of adipocytes. Adipocytes are not a silent fat mass, but increase the hormone level of leptin, which influences neurones in the hypothalamus, the thyreotropic axis and TSH secretion. BMI is positively correlated with serum leptin. Elevated leptin levels, endogenous in individuals with high BMI or exogenous after leptin injection for treatment of hypothalamic amenorrhoea, shift TSH in the upper reference level. Borderline elevated TSH levels are reversible in case of body weight reduction in obese persons. It remains unclear whether high TSH levels or high leptin level are responsible for obesity or represent secondary phenomenon. Recommendation for daily practice: Borderline elevated TSH-levels in obese patients will decrease in case of body weight reduction without hormone medication. After definitive treatment of hyperthyroidism patient's history for use of carbohydrates (increased during hyperthyroidism) should be noticed and substitution with thyroid hormones aims at TSH in the lower reference level. As body weight gain is observed in all TSH groups, a special concept for prevention and therapy of obesity (diet, daily exercise, behaviour training) should be initiated early and additionally to medication.

Markers of function and proliferation in non-invasive and invasive bi- and plurihormonal adenomas of patients with acromegaly: an immunohistochemical study.

Twenty-seven plurihormonal and 21 growth hormone- prolactin- (GH- PRL-) mixed cell adenomas obtained from patients with acromegaly undergoing transnasal-transsphenoidal surgery were investigated immunohistochemically for expression of Epidermal Growth Factor (EGF), Transforming Growth Factor alpha (TGF alpha), Insulin-like Growth Factor-1 (IGF-1), Estrogen Receptor-Related Protein (ERRP), Multidrug Resistance Marker (MDRM), Protein Kinase C (PKC), Gs alpha,. Cathepsin D and p53. Five plurihormonal adenomas grew invasively. The panel of markers used in this study represents a selection of functional and proliferative markers thought to be associated with the function and development of pituitary adenomas. Our results imply that the growth factors (EGF, TGF alpha, IGF-1), the cell signalling protein Gs alpha and the MDRM are expressed by both types of pituitary adenomas in a similar pattern. Non-invasive GH-PRL-mixed cell adenomas showed an increased expression of IGF-1, TGF alpha and MDRM compared to non-invasive plurihormonal adenomas. No factor was found which would reliably distinguish between invasive and non-invasive adenomas. We failed to confirm the findings of others that p53 and cathepsin D might be indicators of tumor aggressiveness. A participation of ERRP and PKC in the development of bi- and plurihormonal adenomas with acromegaly appears unlikely, as the immunostains were all negative.