CONCRETE
Research type
Research Study
Full title
Effectiveness of ClOmipheNe CitRate for the management of mEn wiTh infErtility (CONCRETE): A randomised double-blind placebo-controlled trial.
IRAS ID
1012496
Contact name
Bassel Al Wattar
Contact email
Sponsor organisation
University College London Comprehensive Clinical Trials Unit
ISRCTN Number
ISRCTN16558783
Research summary
The CONCRETE trial is a double blind research study looking at whether a medication called clomiphene can safely and effectively help men with certain fertility problems. These include:
• When the body doesn’t produce enough testosterone due to issues with the brain signals that control hormone production in the testes - Secondary functional hypogonadism
• When the cause for male infertility is unknown - Idiopathic male factor infertility
The study will involve 160 men across several NHS hospitals in the UK. Each participant will be randomly assigned to one of two groups:
• One group will take one tablet of clomiphene citrate 25mg per day.
• The other group will receive a placebo (a dummy treatment with no active medicine)
This helps researchers to understand if clomiphene can help men with low sperm to improve their semen parameters and boost their chances of fathering a pregnancy.
Participants will take clomiphene or placebo for 12 months and be followed up for 21 months. There are three in person follow up visits at month 3, 6, and 12 and one remote follow up call at month 21.REC name
Yorkshire & The Humber - Leeds West Research Ethics Committee
REC reference
26/YH/0057
Date of REC Opinion
8 May 2026
REC opinion
Further Information Favourable Opinion