Effects of Acute Recombinant Human TSH on Serum Ghrelin Levels.
Recent findings showed the presence of a reciprocal relationship between thyroid hormones and ghrelin, although the exact mechanism is not known.


METHODS
Our study is addressed to evaluate the effect of acute exogenous rhTSH administration on serum ghrelin levels in athyreotic patients on replacement l-thyroxine therapy. The study group included 50 patients (16 males and 34 females) submitted to total thyroidectomy and 131-iodine remnant ablation for differentiated thyroid cancer on l-thyroxine therapy. Mean age was 47.5 ± 16.5 years and mean BMI was 25.6 ± 5.01 kg/m(2). rhTSH was administrated at the dosage of 0.9 mg i.m. once daily for two consecutive days. Blood samples were taken between 08.00 and 09.00 after a overnight fasting for measurement of TSH, FT3, FT4, and ghrelin before the first administration of rhTSH and for measurement of TSH and ghrelin 24, 48, 72, and 96 h after the first administration of rhTSH.


RESULTS
Mean ± SD values of basal TSH were 0.54 ± 0.77 μU/ml without significant difference between females and males. As expected, after rhTSH administration TSH concentrations increased at 24 and 48 h with peak TSH values ranging from 20.20 to 313 μU/ml (mean ± SD 98.4 ± 66.7 μU/ml). Mean ± SD values of basal ghrelin were 1085 ± 373 pg/ml without significant difference between males and females. After rhTSH administration ghrelin concentrations decreased significantly (p < 0.01) at 24 h (mean ± SD 934 ± 314 pg/ml p < 0.01) and returned to pre-treatment levels at 96 h.


CONCLUSIONS
Our study demonstrates that acute exogenous TSH administration has a suppressive effect on ghrelin secretion independent from changes in thyroid status.
Section of Endocrinology, Department of Internal Medicine, Endocrinology and Metabolism and Biochemistry, University of Siena Siena, Italy.
Cristina
C
Ciuoli
Lucia
L
Brusco
Alexandra
A
Theodoropoulou
Maria Grazia
MG
Castagna
Ornella
O
Neri
Letizia
L
Pasqui
Furio
F
Pacini