laboratory workup for erectile dysfunction

by Chris Steidle, MD

The laboratory workup for erectile dysfunction includes a variety of evaluations. In our office, we routinely run a urinalysis to check for glucosuria (sugar in the urine) and proteinuria (protein in the urine.) Findings of either might indicate diabetes, possible chronic renal insufficiency or chronic renal failure.

As for the serum laboratory investigation (blood tests), we run a basic chemistry panel to look for signs of chronic renal insufficiency or electrolyte abnormalities. Either could point to underlying chronic disease that could be the cause of the erectile dysfunction.

We also run a test of serum glucose. We prefer to do this as a fasting study to screen for diabetes mellitus.

The testosterone level is also checked to rule out hypogonadism. The effect of hormone levels on sexual functioning is significant and we do see a number of patients with very low serum testosterone.

When looking for hypogonadism or low testosterone level, we see three basic syndromes. One is called hypergonadotrophic syndrome, in which there are high levels of luteinizing hormone (LH) and follicle stimulating hormone (FSA.) These patients have lost their testicles, have congenital, genetic abnormalities such as Klinefelter's syndrome, or testicular injury from radiation, drugs, trauma, or aging.

Another syndrome is known as hypogonadotrophic, which is indicated by low LH and FSH and caused by congenital syndromes, damage to the pituitary gland, or a prolactin problem. We also see miscellaneous problems causing low testosterone, such as liver disease, thyroid disease, chronic renal disease, and diabetes. When we encounter a low testosterone level, we test the levels of LH and FSH as well.

Before recommending androgen therapy, we develop a complete laboratory profile of the patient. Androgen therapy is a double-edged sword. It can be very effective in selected cases, but it is not without such long-term complications as liver disease, elevated cholesterol, and the possibility of prostate cancer.

Once a patient is on androgen therapy, it's important to check their testosterone level in the morning and preferably at the same time every day for a while. If it comes up to a normal level, we stop the treatment. If it stays low, we repeat the treatment. If it is then normal, we stop treatment altogether. If it persists at a low level, however, we check the LH, FSH, and prolactin levels. If we see low LH and FSH with high prolactin, we also do an MRI of the head, thyroid and adrenal glands to check the internal anatomy of the glandular system as a help in finding an accurate diagnosis. If we find an elevated sugar and we know the patient has diabetes, we also run a glycosylated hemoglobin check. This gives us a feeling for how long the patient has had the diabetes problem and gives us prognostic information as to how well the patient will do with therapy.

Last Updated: April 2003