Low Libido / Low Sex Drive

Testosterone levels have a significant and central role in libido for both men and women. In fact, most men with a low testosterone level will suffer from a low libido. This effect seems to be magnified over time, as libido seems to decrease with age more than can be explained by the natural decreases in testosterone levels that come with aging.

Much of the testosterone in the bloodstream is bound by proteins, which makes it less available to get into the tissues themselves. This is why it is important to measure not only absolute testosterone levels, but the amount of available testosterone.

Once the amount of available testosterone has been measured and confirmed, since there is significant variability in testosterone levels over even short periods of time in any particular individual, and found to be consistently low, testosterone replacement therapy (TRT) can be started.

It is always important to remember that testosterone from the outside will temporarily shut down a man’s own production of testosterone. If the testes are not making high levels of testosterone, sperm production is decreased or stopped. Men who still want to have children must either bank sperm prior to starting testosterone replacement therapy or use medications such as HCG, which increase the testicular production of testosterone without shutting down sperm production.

For unknown reasons, probably relating to brain chemistry, it may take a man nine months of good testosterone levels on TRT, to notice a significant change in libido. This is often quite frustrating for the man and his partner.  Thus, we make sure to discuss this delayed response at the beginning of treatment.

Fortunately, the vast majority of men will have a significant improvement in their libido with testosterone replacement therapy, even if there are other psychological or relationship issues present.

What is Prolactin?

Prolactin is a hormone made by your pituitary gland, which is a small (pea-sized) structure at the base of your skull. It is the hormone that make the milk producing glands in the breast enlarge and secrete breast milk. Men, as well as non-pregnant and non-breastfeeding women, have a low base level as well.

Why Can it Be Elevated/Why Does it Matter?

The pituitary gland can develop a prolactinoma which is a non-cancerous growth. The cells produce an excess of prolactin, which can cause breast enlargement and breast secretions. The hormone prolactin has a negative effect on libido. It also usually suppresses the production of testosterone, which has its own negative effect on libido. The growth can have other negative effects by damaging the structures it grows into, especially the nerves leading to the eyes.

How is it Treated?

Fortunately, the pituitary adenoma can usually be treated with medication that suppresses and sometimes ultimately destroys the growth. If it cannot be treated medically, it is usually surgically removed.

Prolactin and Libido

As mentioned above, increased prolactin can have a very negative effect on libido. First, prolactin itself seems to suppress libido. Many breastfeeding women, for example, will notice a decreased libido, which often improves once they stop breastfeeding. In other words, the loss of libido is not solely due to having an infant.

Increased prolactin also has a significant effect on men’s libido because it will often suppress production of testosterone.

Interestingly, and unfortunately, when the prolactinoma is treated, and the prolactin levels come down, the testosterone levels often do not come back up. These men, if symptomatic, will often need to begin testosterone replacement therapy.

It is crucial that all men (and women) with low libidos have not only their testosterone levels checked but also their prolactin levels.

What is DHEA-S?

DHEA-S is Dehydroepiandrosterone sulfate. It is produced by the adrenal gland, a small gland above the kidneys. It is a precursor for many other hormones, meaning it is converted into other hormones by enzymes.

Lower DHEA-S levels are found in people with Alzheimer’s disease, heart disease, depression, diabetes, inflammation, immune disorders, and osteoporosis.

There is reasonable evidence that increasing DHEA-S levels may help in the treatment of depression, obesity, and osteoporosis. There are some papers that have shown that individuals with higher DHEA-S levels live longer. However, this conclusion is far from proven.

There is also reasonable evidence that increasing DHEA-S levels can improve libido in premenopausal women.

How is a DHEA-S Measured?

Measuring DHEA-S is a simple blood test. You do not need to be fasting, and it does not matter what time of day it is drawn.

How is Low DHEA-S Treated?

Once you and your physician decide that DHEA-S supplementation is appropriate, DHEA-S is simply taken as a daily pill. Starting dosage is usually 25 mg daily. It is important that it come from a reputable company that continually checks its supplements for purity and content. In our practice, we simply give it to the patients, as it is very inexpensive, and we make sure it comes from a reputable source. We aim to get our patients into the high range of normal.

What are the Functions of Thyroid Hormones?

The thyroid is a butterfly shaped gland, in the front of the neck, below your voice box.  It makes three hormones:

• Triiodothyronine or T3
• Tetraiodothyronine, also called thyroxine, or T4
• Calcitonin

T3 and T4 are the hormones that we usually speak about when we talk about thyroid hormones.  (Calcitonin is involved in calcium and bone metabolism.)

Generally, thyroid hormones are responsible for metabolic rates and energy.

What Happens With Too Much or Too Little Thyroid Hormone?

The thyroid may be overactive and make too much of the thyroid hormones, which is called hyperthyroidism.  It may be under active, and make too little of the thyroid hormones, which is called hypothyroidism.

Too much of the thyroid hormones (hyperthyroidism), speeds up the metabolism, and can cause any or all of these symptoms:

• Hot flashes sweating
• Tremors
• Weight loss
• Diarrhea
• Hair Loss
• Nervousness, hyperactivity
• Emotional issues, irritability
• Fatigue
• Insomnia and/or  restlessness
• Racing heart
• Erection Issues

Too little of the thyroid hormones (hypothyroidism), slows down the metabolism and can cause any or all of these symptoms:Decreased Libido

• Decreased Libido
• General loss of energy
• Weight gain
• Decreased focus and mental agility
• Constipation
• Cold Sensitivity
• Waxy skin thickening and swelling
• Dry skin and/or brittle and dry hair
• Depression
• Erection Issues

How are Thyroid Hormone Issues Diagnosed and Treated?

Part of a good hormone screen for decreased libido must include looking for thyroid abnormalities. The usual recommendations are to measure Free T3 and Thyroid Stimulating Hormone (TSH). If either of these is abnormal, then thyroid issues need to be considered. The full diagnosis and treatment methods are beyond the scope of this summary, but are relatively straightforward. However, if your TSH is found to be elevated, particularly if it is above 10, then thyroid hormone replacement therapy must be seriously considered.

Serotonin is produced primarily in the gastrointestinal tract and some is also produced in the brain. In order to increase serotonin levels, patients with depression or anxiety are often treated with SSRIs which stands for selective serotonin reuptake inhibitors or serotonin-specific reuptake inhibitors. SSRIs are used for depression and generalized anxiety disorder (GAD).

SSRIs work not by producing more serotonin, but by decreasing their reabsorption. In other words, more serotonin stays in the nervous system longer.

SSRIs are the most commonly prescribed antidepressants. Common SSRIs include: Prozac (fluoxetine), Zoloft (sertraline), Paroxetine (Paxil), Lexapro (escitalopram), Celexa (citalopram), and Luvox (fluvoxamine).

Work is always being done to create medications that increase serotonin, and treat depression, anxiety, irritability, and OCD without sexual side effects. A relatively new medication, Brintellix, at lower doses (5 and 10mg) seems to have minimal sexual side effects.

Erections

Increasing serotonin does not in general have an effect on erectile function and there is no increased incidence of erectile dysfunction for men starting or taking SSRIs.

Ejaculation

Increasing serotonin will often significantly increase a man’s threshold for reaching an orgasm. This is a particularly useful side effect that can be used to treat men with premature ejaculation (PE). However, for some men, this may cause a complete inability or significant difficulty in reaching a climax, particularly with intercourse. This may have a negative influence on a man’s desire to engage in intercourse and thus an indirect negative effect on libido.

Libido

Increased serotonin levels often decreases libido. Depression itself can, of course, have a negative effect on libido. However, the SSRIs, even while improving depression do not improve libido.

If a man needs to be on an SSRI to treat his depression, several factors may be considered to diminish their impact on libido.

First, usually he can lessen the effect on libido by lowering the dosage. Often, over time, the dosage used to treat depression can be decreased.

Second, every man’s brain chemistry is  unique. Various SSRIs not only affect  men differently, but also may affect their libidos differently.

Third, an additional antidepressant (such as bupropion) may be added, which may in and of itself increase libido, but may also make it possible to treat the depression with a lower dosage of a SSRI.

Dopamine, like serotonin, is a neurotransmitter, a chemical messenger causing neurological impulses in the brain. Dopamine pathways in the brain play an important role in motivation. Most rewards increase the level of dopamine in the brain. Also, anticipating a reward, increases dopamine levels, which causes an individual to act in a way to get the reward.  Most addictive drugs increase dopamine neuronal activity.

Dopamine’s Effects on Libido

Increased dopamine levels in the brain correlate to an increased libido. One can increase brain dopamine levels by either increasing the actual levels, through an oral medication, or by preventing the depletion of dopamine by changing behavior.

Oral Medications to Increase Dopamine

The only medication currently used to increase dopamine to treat depression is bupropion, which is available in the United States generically or branded as Wellbutrin. The mechanism of action of bupropion is not well understood. However, it is thought to inhibit the reuptake of dopamine, thus increasing the amount of dopamine present in the brain.

Bupropion is available in three formulations, which differ in how quickly the medication is released.

Most practitioners start their patients on the extended release (XL). It is available in 150mg and 300mg tablets. The maximum daily dosage is 450mg.

Decreasing Dopamine Depletion

Pornography is thought to deplete brain dopamine. Men who watch a lot of pornography, particularly hard core pornography, appear to deplete the dopamine levels in their brain. This leads to increasing desire to watch more pornography, and more extreme pornography. Their interest in actual sex will often be significantly diminished.

We advise our patients suffering from low libido to significantly decrease the time they spend watching pornography, and limit the pornography that they do watch to scenes which are most like what they would actually be engaged in.

Many men will need to be on a medication to treat depression. Clearly, depression has a significant negative effect on men’s lives, and can be life threatening. Depression also has a significantly negative effect on libido. As partially described above, there are several classes of antidepressants. While serotonin reuptake inhibitors can have a negative effect on libido, bupropion does not.

However, not all men with depression respond to bupropion. Also, while SSRIs help manage symptoms of anxiety, irritability, and OCD, bupropion does not.

However, sometimes bupropion can be added to an SSRI. This may improve libido. It also may mean that the man’s depression can be well managed with a lower total dosage of the SSRI.

Other antidepressants increase both serotonin and norepinephrine. They are called serotonin norepinephrine reuptake inhibitors (SNRIs). SNRIs may diminish libido less than SSRIs (which increase only serotonin, but not norepinephrine) in some men.

Newer medications that increase serotonin have been an important focus of medical research. Brintellix increases serotonin, but at lower dosages seems to have minimal effect on libido (or in delaying ejaculation).