Libido issues can unfortunately be difficult to pin down sometimes because there are many factors, both intrinsic and extrinsic, that affect it.

Libido is primarily governed by dopamine. So bear in mind that this is a neurotransmitter that there is no test for, though there are medications to increase it known as dopamine agonists. There are two types: ergoline and non-ergoline. You may have heard of cabergoline (ergoline) or pramipexole (non-ergoline). These medications are actually primarily used for Parkinson's Disease, but funnily enough, they both have warnings on their labels about the increased libido. In my over 16 years treating both men and women with libido issues, I have never seen these medicines not significantly improve libido.

There is no blood test for dopamine levels, so typically if dopamine is felt to be the cause, then a trial of caber or prami is used to see if there is improvement. Symptom improvement tends to be rather quick, usually within a few days.

After dopamine, the rest of the physiologic factors are hormonal, and in order they are testosterone, DHT, oxytocin, and then estrogen. Each of these has been scientifically proven to have effect on libido. With the exception of oxytocin, each of these can be measured with commercially available blood tests.

Prolactin outside of the normal range (high or low) also seems to have some effect on libido. Science has still not determined why this is the case. This can be measured with a simple blood test.

DHEA appears to affect libido, though so far studies have concluded that this is the case because it increases testosterone. While this level can be tested, it does not typically provide any useful information in a patient on TRT. Pregnenolone testing typically only comes with an ACTH stimulation test, is never covered by insurance, and costs about $800 so we do not routinely recommend this test.

Because both DHEA and pregnenolone are both over the counter and cheap (2 month supply for $4 on Amazon), we suggest supplementation over expensive labs. Any improvement on a trial of these supplements would be an easy diagnostic/therapeutic measure to try first.

Based on your symptoms, you absolutely should consider getting your prolactin tested.