Thyroid and sympathetic influences on plasma leptin in hypothyroidism and hyperthyroidism
2000
Pinkney, J.H. | Goodrick, S.J. | Katz, J.R. | Johnson, A.B. | Lightman, S.L. | Coppack, S.W. | Medbak, S. | Mohamed-Ali, V.
Objectives: To determine the dependence of plasma leptin concentrations upon circulating noradrenaline (NA) and thyroid hormones (TH) in humans. Design: Cross-sectional study in 40 newly diagnosed untreated patients with primary thyroid disease, and 69 lean and obese euthyroid control subjects. Measurements: Plasma leptin, NA, free T3 (fT3) and TSH in the fasting state. Anthropometry and % body fat (electrical bioimpedance). Results: Leptin levels were highest in 37 obese euthyroid and 22 hypothyroid (median [interquartiles]31.5[19.0-48.0], 19.2[11.5-31.5]ng ml-1), and lowest in 32 lean euthyroid and 18 hyperthyroid subjects (6.6[3.9-14.4], 8.9[5.5-11.1]; ANOVA, P < 0.0001). Plasma NA was similar in all groups (P=n.s.). In obese controls, TSH correlated with % body fat and leptin (r=0.67, r=0.61; P < 0.001). Treatment of hypothyroidism (n=10) with T4 reduced leptin from 20.8[11.8-31.6] to 12.9[4.6-21.2] (P=0.005) with no change in BMI. Conclusions: Thyroid status modifies leptin secretion independently of adiposity and NA. The data suggest leptin-thyroid interactions at hypothalamic and adipocyte level.
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