Testosterone is the sex hormone most responsible for inspiring puberty in males, but females also produce small amounts that regulate some of their reproductive functions. Excessive levels of testosterone in both males and females can have deleterious effects on a number of biological processes, whether the testosterone is produced naturally or administered as hormone therapy.
Testing
A doctor may call for testosterone testing in male children experiencing precocious puberty, or puberty that comes earlier than expected. Adult males with decreased sex drive or erectile dysfunction may be tested for insufficient testosterone levels, while adult females who have difficulty getting pregnant or have irregular or non-existent menstrual periods may be tested for excessive testosterone.
Causes
Naturally high levels of testosterone can indicate problems of the pituitary or hypothalamus, but certain medical conditions, and even treatments, can cause testosterone levels to rise. Cancer cells in the prostate respond actively to testosterone, which could cause a spike in production. Women undergoing hormone therapy with estrogen, the female sex hormone, may react by producing excessive levels of testosterone. Also, men or women taking anticonvulsants or barbiturates may see their testosterone levels rise.
Neurological Effects
A September 2006 study published in the "Journal of Biological Chemistry" found causation between excessive levels of testosterone and neural apoptosis, or nerve cell death. Apoptosis differs from necrosis, or traumatic cell injury, in that it is a necessary part of biological function. Adults experience billions of cell deaths each day due to apoptosis. However, the study found that excessive testosterone acts on nerve cells specifically, causing an "apoptotic cascade," which could have long-term effects on brain activity.
Neo-natal Concerns
Dr. Sven M. Carlsen of the University of Trondheim has discovered a possible link between excessive testosterone levels in women during pregnancy and low birth weight. Dr. Carlsen explains that elevated testosterone levels have an impact on birth weight equal to known factors such as maternal smoking. He presented his findings before the European Congress of Endocrinology in a paper titled "Maternal Testosterone Levels in Pregnancy are Associated with Offspring Size at Birth."
Hair Growth
Excessive levels of testosterone are associated with increased follicular activity leading to unwanted hair growth. The hormone affects different parts of the body to different degrees. In men, high levels of testosterone leads to excessive hair growth on the back and across the abdomen, while in women it often presents on the face.
