Testosterone Testing, Treatment Soar Despite Uncertainties

Nancy A. Melville

January 10, 2014

With testosterone testing increasing dramatically in the United States and United Kingdom since 2000, the rate of testosterone supplementation has nearly quadrupled in the United States during that period, while the rate has increased by 30% in the United Kingdom, according to new research published online January 1 in the Journal of Clinical Endocrinology & Metabolism.

A higher rate of low testosterone levels detected in the United Kingdom, however, suggests a more accurate identification of patients who are most appropriate for testing in that country.

"Interestingly, the increased testing in the UK seems to be more targeted, identifying more individuals with reduced testosterone levels," the authors note. In contrast, "the US seems to be testing more and more men with normal levels."

The prevalence of direct-to-consumer (DTC) marketing of branded pharmaceutical products in the United States but not the United Kingdom, where such ads are prohibited, appears to offer one logical explanation for the differences, they suggest.

"Heavy direct-to-consumer marketing of newer testosterone formulations in the US may have led to a much wider interest in testosterone levels and hypogonadism symptoms, resulting in wider testing of men with nonspecific symptoms but normal levels rather than targeted testing of symptomatic individuals," say J. Bradley Layton, PhD, from the University of North Carolina, Chapel Hill, and colleagues in their paper.

They caution also that there are discrepancies in estimates of the lower end of a normal testosterone level and say they would strongly discourage treatment based on just one low testosterone measurement, recommending instead further investigations. And they document a switch away from generic testosterone injections to brand-name gels over the past 5 years.

Supplementation with Testosterone Less Frequent in United Kingdom

For the retrospective study, Dr. Layton and his colleagues evaluated commercial and Medicare insurance claims from the United States and general practitioner records from the United Kingdom between 2000 and 2011.

They identified 1,114,329 men in the United States and 66,140 men in the United Kingdom who had a new testosterone laboratory measurement during the study period, and 410,019 men in the United States and 6858 in the United Kingdom who initiated therapy with a testosterone formulation.

New testosterone testing in untreated individuals in the United States increased from 39.6 per 10,000 person-years in 2000 to 170.0 per 10,000 person-years in 2010.

In the United Kingdom, the testing rate increased from 13.0 per 10,000 person-years in 2000 to 46.4 per 10,000 person-years in 2010.

Despite the increases in testing, the proportion of assay results that were found to be low in the United States stayed constant over that period, while the proportion of normal results increased slightly from 64.5% to 73.2%.

In contrast, the proportion of tested men with low assay results in the United Kingdom increased from 18.9% in 2000 to 26.7% in 2011, with corresponding declines in normal and high assay results.

About 36% of men in the United States found to have low levels of testosterone began supplementation in 2007, and the figure increased to 43% by 2011.

In the United Kingdom, only about 10% of men with low levels started testosterone therapy, and the rate remained constant from 2000 to 2011.

Those found to have normal or high testosterone levels in the United States received supplementation in approximately 4% to 9% of cases, while the rate was approximately 1% or less of cases in the United Kingdom.

Switch from Injections, Patches to Gel Formulations

The researchers found a significant shift away from injections and patch formulations to topical gel formulations over the course of the study, with gels representing the most common formulation used by the end of the study period.

"The newer gels are branded and have been widely marketed in the United States, whereas injections, which were previously the standard, are mostly generic," Dr. Layton told Medscape Medical News.

He noted that in addition to the influence of marketing of testosterone products in the United States, there has been a general increased interest in fluctuations in testosterone levels during the aging process.

"There is clearly widening interest in testosterone levels in middle-aged and older men, including greater recognition of naturally lowering testosterone levels throughout older age and in chronic disease states. This has been coupled with widespread campaigns encouraging men to have their testosterone levels checked in the US," Dr. Layton said.

While testosterone levels naturally decrease gradually with age and in the presence of factors including chronic disease, obesity, or smoking, most guidelines recommend supplementation only when patients have symptoms and have low testosterone levels that are confirmed by repeated laboratory tests.

The Endocrine Society's clinical practice guidelines, for instance, recommend a clinical diagnosis of androgen deficiency, or low testosterone, only when men show consistent symptoms and unequivocally low testosterone levels.

The treatment of older men based on one low testosterone measurement is discouraged.

Testosterone May Be Harmful; Pause before Prescribing

Complicating matters further are discrepancies in estimates of the lower end of a normal testosterone level, which range from 200 to 350 ng/dL, in addition to wide variation in results between laboratories, the authors point out.

They add that many testosterone assay reference ranges reflect populations of healthy, younger men and may not be applicable to older populations.

While there are no clear benefits from testosterone treatment when it's not clinically indicated, there can be risks, Dr. Layton said.

"There may be potential risks, which are being widely investigated by research teams around the world: there have been recent suggestions of cardiovascular events in older men with previous CVD taking testosterone, and concerns about prostate cancer exist."

When confronted with a patient without symptoms and only one low testosterone test result, Dr. Layton recommends that clinicians hesitate before writing that prescription.

"A single low testosterone lab measurement may warrant further investigation but does not necessitate treatment automatically," he said.

The study received funding from the National Institute of Health's National Institute on Aging. The authors have reported no relevant financial relationships.

J Clin Endocrinol Metab. Published online January 1, 2014. Abstract

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