Reduced serum acylated ghrelin levels in patients with hyperthyroidism

BACKGROUND AND OBJECTIVE: Recent studies have revealed that circulating ghrelin levels seem to play a role in energy homeostasis. The effect of hyperthyroidism on ghrelin levels is not fully known. METHODS: Serum levels of ghrelin and its relationship with insulin resistance were evaluated in 48 patients with hyperthyroidism and 43 euthyroid healthy controls. Thyroid hormones, insulin, glucose, ghrelin levels and lipid parameters were measured in all subjects. Insulin sensitivity was determined using the homeostasis model assessment. RESULTS: Serum ghrelin levels were significantly decreased in hyperthyroid patients than in controls (32.5 +/- 23.3 vs. 54.1 +/- 35.5 pg/ml, p < 0.001). Circulating ghrelin levels significantly correlated with age (r = -0.26, p = 0.01), fasting glucose (r = -0.21, p = 0.01), free triiodothyronine (r = -0.18, p = 0.04), free thyroxine (r = -0.23, p = 0.02) and thyroid stimulating hormone (r = 0.21, p = 0.04), but not with blood pressure, body mass index, lipid parameters, insulin and homeostasis model assessment (p > 0.05). Multiple regression analysis revealed glucose level to be the most important predictor of circulating ghrelin level. CONCLUSION: These results indicate that hyperthyroidism has effect on serum ghrelin levels. Further studies are needed for the exact mechanism.     

Elevated serum IL-16 and RANTES levels in patients with autoimmune thyroid diseases and modulation by methimazole therapy

Interleukine-16 (IL-16) and RANTES (regulated upon activation, normal T cell expressed and secreted) are 2 cytokines with the function of T helper cell recruitment, which might play a key role in pathogenesis of autoimmune thyroid diseases (AITD). This study was aimed to evaluate the IL-16 and RANTES in patients with AITD. Serum IL-16 and RANTES levels were measured in patients with Graves' disease (GD; n=45), Hashimoto's thyroiditis (HT; n=68), nontoxic multinodular goiter (NTMNG; n=20), and healthy individuals (n=61). The results showed that serum IL-16 and RANTES levels were elevated both in HT and higher in untreated GD patients when compared to NTMNG patients and the healthy individuals, which were decreased after MMI therapy in untreated GD patients. However, in HT patients, serum IL-16 and RANTES levels were comparable among the conditions of hyperthyroid and euthyroid received by l-thyroxine therapy and untreated hypothyroid. Furthermore, serum IL-16 levels were correlated with FT3, FT4, TRAb in GD, but not in HT patients. The data did not show any correlation between RANTES levels and clinical factors. In conclusion, IL-16 and RANTES might be involved in the pathogenesis of GD and HT, and serum IL-16 levels in GD maybe a potential marker of disease activity and severity.     

No monthly variations in serum levels of thyroid hormones in human males

There have been very few reports on rhythmic variation in thyroid hormone concentrations with a periodicity of 4-6 weeks. In an attempt to evaluate whether such a rhythm is a general phenomenon we studied ten healthy male students with weekly blood samples over 12 weeks for T4, T3 and TSH. No rhythmicity could be demonstrated.     

Effect of thyroid hormones on the levels of metabolic intermediates in diabetic rat liver

Experimental diabetes results in an inhibition of the glycolytic and lipogenic pathways in rat liver, while treatment of diabetic rats with T3 for four days increases the activity of a number of enzymes linked to lipogenesis. Hepatic metabolites were estimated in control (untreated), control + T3-treated, alloxan-diabetic and alloxan-diabetic + T3-treated rats. Diabetes resulted in the expected decrease in the content of fructose 2,6-bisphosphate and an increase in the content of cyclic AMP and citrate, changes consistent with an inhibition of hepatic glycolysis. Treatment of diabetic rats with T3 did not reverse these changes. There was a marked accumulation of both acetyl CoA and citrate in the diabetic rat liver, which was of even greater magnitude in diabetic and in the T3-treated group. In addition, T3 treatment significantly increased the free CoA content of liver in both normal and diabetic groups. Of the parameters measured which influence lipogenesis, including long chain acyl CoA, the energy charge and redox state of the nicotinamide nucleotides, the raised hepatic citrate content correlated most closely with the known increase in lipogenesis in diabetic rats treated with T3 for a four day period.     

Thyroglobulin levels in serum and saliva of patients with differentiated thyroid carcinoma

Serum thyroglobulin levels in 39 patients with differentiated thyroid carcinoma and in 10 healthy volunteers were studied by radioimmunoassay. Sera from two of these patients were analysed preoperatively. Both of these sera showed thyroglobulin levels higher than that obtained from normal individuals. Serum thyroglobulin levels of 10 normal subjects varied between 1·0 to 20·0 ng/ml, Thirteen patients who were in remission showed serum thyroglobulin levels between 0·1 to 18.5 ng/ml which is within the normal range. Patients with bone metastasis had elevated serum thyroglobulin levels while those with lung metastasis had normal serum thyroglobulin levels. Salivary secretion from normal subjects showed thyroglobulin levels between 0·8 to 7·0 ng/ml., while that from thyroid cancer patients ranged between 0.4 to 27.5 ngjml, It appears that salivary thyroglobulin is atpari passu with serum thyroglobulin levels.     

Effect of sex and age on serum aldosterone and thyroid hormones in the laboratory rat

Serum levels of aldosterone, tri-iodo thyronine (T3) and thyroxine (T4) were measured in male and female rats aged 3 months, 12 months, and 18 months. Female rats were found to have higher aldosterone and T3 levels, and lower T4 level than the male. No age-related change was observed in serum aldosterone in either sex. In contrast, serum T4 were found to decrease with age in both sexes while serum T3 showed an age-associated diminution in the male only. Serum testosterone was also measured in the male rats and was found to decline with age.