Decreased facial or body hair
Dilated veins around the testicle
Ejaculation problem
Frequent respiratory infections
Hormonal imbalance
Inability to conceive a child
Inability to smell
Low libido
Low sperm count
Swelling or a lump in the testicle area
Abdominal surgeries
Anti-sperm antibodies
Cancers
Certain medications
Chemotherapy
Defects of the sperm transporting tubules
Emotional stress
Exposure to heavy metals and industrial chemical including benzenes, toluene, xylene, pesticides, herbicides, etc
Hormone imbalances
Hypospadias
Illegal drug use
Inguinal hernia repairs
Kallmann's syndrome
Kartagener's syndrome
Overheating the testicles due to frequent use of saunas or hot tubs, tight clothing, etc
Premature ejaculation
Prostate surgeries
Psychological or relationship problems
Radiation therapy
Scrotal or testicular surgeries
Surgery of the bladder, prostate, or urethra
Vasectomy
Urologist