A Phase 2/3 interventional study of Letrozole 2.5mg and L-carnitine in Idiopathic Oligoasthenoteratozoospermia and Male Infertility, sponsored by Tehran University of Medical Sciences. Completed at 1 site in Iran. Open to male participants aged 20 Years to 45 Years. Per ClinicalTrials.gov, last updated 2026-06-30.
Sponsored by Tehran University of Medical Sciences · Phase 2/3, Interventional, and Treatment
This is a randomized clinical trial evaluating the efficacy of Letrozole, L-Carnitine, and their combination on sperm quality, oxidative stress, and ART outcomes in men with idiopathic oligoasthenoteratozoospermia.
This three-arm randomized controlled trial included 90 men with idiopathic oligoasthenoteratozoospermia (iOAT) who were assigned to receive Letrozole (2.5 mg/day), L-Carnitine (1000 mg/day), or combination therapy for 3 months. Sperm parameters, hormonal profiles, oxidative stress biomarkers, mitochondrial function, and ICSI outcomes were assessed before and after treatment.
64 studies on the registry are indexed under Oligospermia; 17 are open to participants now.
This study's enrollment of 90 is above the median of 65 across 46 interventional studies indexed under Oligospermia.
Browse Oligospermia studies →Tehran University of Medical Sciences is the lead sponsor of 231 studies on the registry; 12 are open to participants now.
Compared within Oligospermia, this study's primary condition as ClinicalTrials.gg classifies it; the registry's first condition term is Infertility, Male. The counts are of registry records indexed under each term, refreshed daily. How we classify →
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Diagnosis of idiopathic oligoasthenoteratozoospermia (iOAT) per WHO 2021 criteria
Age 20 to 45 years
between 18 and 30 kg/m²
No prior hormonal therapy or antioxidant supplements within the last 3 months
Exclusion Criteria:
Varicocele, cryptorchidism, or genital tract infection
Hormonal disorders (hypogonadism, hyperprolactinemia, thyroid dysfunction)
Smoking, alcohol use, or drug abuse
Use of testosterone or anabolic steroids within the last 6 months
Female partner with severe infertility factors (age ≥40, tubal blockage, severe endometriosis)
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Letrozole 2.5 mg administered orally once daily for 3 months.
Drug: Letrozole 2.5mg
L-Carnitine 1000 mg administered orally once daily for 3 months.
Drug: L-carnitine
Letrozole 2.5 mg plus L-Carnitine 1000 mg administered orally once daily for 3 months.
Drug: Letrozole 2.5mg · Drug: L-carnitine
Letrozole 2.5 mg tablet administered orally once daily for 3 months.
L-Carnitine 1000 mg capsule administered orally once daily for 3 months.
Sperm concentration (×10⁶/mL) after 3 months of treatment
Change in sperm concentration from baseline to 3 months post-treatment
Time frame: 3 months
Progressive sperm motility (%) after 3 months of treatment
Change in progressive motility from baseline to 3 months post-treatment
Time frame: 3 months
Normal sperm morphology (%) after 3 months of treatment
Change in normal morphology from baseline to 3 months post-treatment
Time frame: 3 months
Serum testosterone and estradiol levels after 3 months of treatment
Change in hormonal profile from baseline to 3 months post-treatment
Time frame: 3 months
Sperm DNA fragmentation index (DFI) after 3 months of treatment
Change in DFI from baseline to 3 months post-treatment
Time frame: 3 months
Total antioxidant capacity (TAC) and reactive oxygen species (ROS) levels after 3 months of treatment
Total antioxidant capacity (TAC) and reactive oxygen species (ROS) levels after 3 months of treatment
Time frame: 3 months
Mitochondrial membrane potential (MMP) after 3 months of treatment
Change in MMP from baseline to 3 months post-treatment
Time frame: 3 months
Fertilization rate and embryo quality after ICSI
Assessment of fertilization rate and embryo quality following ICSI
Time frame: 3 months
Percentage of patients with improved sperm parameters (concentration, motility, morphology) after treatment
Proportion of patients showing clinical improvement in at least one sperm parameter
Time frame: 3 months
Incidence of treatment-related adverse events
Monitoring and recording of any adverse events related to the study interventions
Time frame: 3 months
Pregnancy outcomes (biochemical and clinical) following ICSI
Assessment of biochemical and clinical pregnancy rates after embryo transfer
Time frame: 3 months
Plan to share: No — Due to the specific nature of the data and restrictions from the ethics committee, individual participant data (IPD) will not be shared.
No publications or documents are linked to this record.
Ran from Dec 2023 to primary completion in Feb 2026, 26 months.
How these figures are worked out, and which studies are left out of them.
This study is completed, as verified in Jun 2026. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Studies of the drugs tested here: Letrozole · Carnitine
Tehran University of Medical Sciences →