There are 4 studies that match your criteria.
Criteria: Freq Range=300 kHz - 300 GHz (RF/mmW/THz),Study Type=In Vivo,Study Subtype=Hormone Changes,Status=Completed Without Publication

Details - Project ID 66
Lab	University of Kuopio, Finland
Study Design	900 MHz (GSM), 50 Hz (ELF) exposure to mice and analysis of melatonin
Summary	No effect (via 6-OHMS excretion)
Citation	Heikkanen, P et al. Electro Magnetobiol, (1999) 18:33-42
Details - Project ID 90
Lab	University of Mainz, FRG
Study Design	900 MHz (GSM, CW)exposure to rats and hamsters and analysis of melatonin levels and immune function
Summary	No effects on 6-OHMS (melatonin) excretion or immune parameters
Citation
Details - Project ID 553
Lab	Res. Inst. for Radiobiol & Radiohyg, Hungary
Study Design	900, 1800 MHz (GSM) exposure to rats and analysis of melatonin
Summary	No effects on 6-Sulfatoxy-Melatonin metabolite excretion or N-Acetyltransferease enzyme activity in the pineal gland
Citation	Bakos, J et al. Bioelectromagnetics, (2003) 24:531-534
Details - Project ID 987
Lab	Hospital Ramon y Cajal, Spain
Study Design	900 MHz (GSM) exposure to rats and analysis of melatonin
Summary	No effects of exposure on neuroendocrine response
Citation