it is entirely normal for one testicle to be bigger than the other. Many people find that the right testicle is slightly larger and the left hangs lower. A difference in size is usually nothing to worry about, though it can occasionally indicate a problem.
This is perfectly normal and nothing to worry about. Either side may be slightly larger or hang lower. But be sure to tell a parent (who will let your doctor know) if you have any pain, swelling, or lumps in your testicles.
When a vein in a testicle becomes enlarged, it's called a varicocele. Varicoceles affect up to 15 percent of males. Like varicose veins in your legs, varicoceles may appear bulgy under the skin of your scrotum. They tend to form in the left testicle because the vein on the left side hangs lower.
Vitamin B12 deficiencies can lead to megaloblastic anemia, a condition where the bone marrow produces large abnormally shaped red blood cells that do not function properly. Dementia, paranoia, depression, and behavioral changes can result from a vitamin B12 deficiency. Neurological damage sometimes cannot be reversed
