Daytime circulating melatonin levels in smokers.
OBJECTIVE
Melatonin secretion is required to be a potential inhibitor of the development and growth of tumors, and cigarette smoking is a well established risk factor for cancer at various sites.


METHODS
Circulating melatonin levels of 20 smokers and 20 non smokers (controls), sampled at the same hour from awaking in order to obtain a comparable circadian synchronization, were compared.


RESULTS
Our data showed higher melatonin circulating levels in smokers (17.44 +/- 1.8 pg/ml) than in nonsmokers (9.77 +/- 1.4 pg/ml).


CONCLUSIONS
The causes, mechanism and meaning of this phenomenon are still unknown. The most attractive hypothesis considers higher melatonin levels in smokers as an attempt to counterbalance cellular growth stimulus, a natural "brake" mechanism to restrain the proliferation of normally differentiated tissues: smoke is a prominent risk factor for several different tumors.
Tarquini
B
B
Cattedra di Medicina Interna I, University of Florence, Italy.
Perfetto
F
F
Poli
R
R
Tarquini
R
R
D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008550:Melatonin / Q000097:blood*; D008875:Middle Aged; D012907:Smoking / Q000097:blood*; D013997:Time Factors
D008550:Melatonin