Thyroid and sympathetic influences on plasma leptin in hypothyroidism and hyperthyroidism.
OBJECTIVE
To determine the dependence of plasma leptin concentrations upon circulating noradrenaline (NA) and thyroid hormones (TH) in humans.


METHODS
Cross-sectional study in 40 newly diagnosed untreated patients with primary thyroid disease, and 69 lean and obese euthyroid control subjects.


METHODS
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.
Pinkney
J H
JH
Department of Medicine, University of Bristol, Bristol Royal Infirmary, UK. J.Pinkney@Bris.ac.uk
Goodrick
S J
SJ
Katz
J R
JR
Johnson
A B
AB
Lightman
S L
SL
Coppack
S W
SW
Medbak
S
S
Mohamed-Ali
V
V
D005260:Female; D006801:Humans; D006980:Hyperthyroidism / Q000097:blood*; D007037:Hypothyroidism / Q000097:blood* / Q000188:drug therapy; D020738:Leptin / Q000378:metabolism*; D008297:Male; D009638:Norepinephrine / Q000097:blood; D009765:Obesity / Q000097:blood; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D013961:Thyroid Gland / Q000503:physiopathology*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000627:therapeutic use; D014284:Triiodothyronine / Q000097:blood
D020738:Leptin; D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine; D009638:Norepinephrine