Study Shows Health Benefits of Testosterone Replacement
Farid Saad, PhD
HOUSTON—Long-term testosterone treatment in hypogonadal men can lead to significant weight loss and improvements in components of metabolic syndrome, according to two new studies presented at The Endocrine Society's 94th Annual Meeting. Both studies were conducted in Germany and used a slow-release, injectable form of testosterone (testosterone undecanoate).
“The substantial weight loss found in our study, an average of 36 pounds, was a surprise,” said lead researcher Farid Saad, PhD, who is with Gulf Medical University, Ajman, United Arab Emirates, and Berlin-headquartered Bayer Pharma.
Dr. Saad and his colleagues conducted an open-label, single-center, cumulative, prospective registry study. The trial included 255 men aged 38 to 83 years (mean age 60.6 years). For this investigation, 215 men were studied for at least two years, 182 men were studied for three years, and 148 men were studied for four years. A total of 116 men had at least five years of follow-up.
Prior studies using testosterone therapy in testosterone-deficient men have consistently showed changes in body composition, such as increased lean mass and decreased fat mass. However, the net effect on weight seemed unchanged in those studies, according to Dr. Saad. This current study had a longer follow-up and used long-acting injections of testosterone than the previous studies.
The investigators restored testosterone to normal levels in 255 hypogonadal men and the treatment lasted for up to five years, with injections given at day 1, after 6 weeks, and then every 12 weeks after that. Patients did not follow a controlled diet or standard exercise program but received advice to improve their lifestyle habits.
On average, the men weighed 236 pounds before beginning testosterone treatment and 200 pounds after treatment (106.2 vs. 90.07 kg). Weight loss was reportedly continuous, with an average reduction in body weight ranging from about 4% after one year of treatment to more than 13% after five years. Men lost an average of nearly 3.5 inches (8.8 cm) around their waist. The study showed that waist circumference declined from 107.24 to 98.46 cm. In addition, body mass index (BMI) declined from 33.93 to 29.17 kg/m2. The mean weight loss after one, two, three, four, and five years was 4.12%, 7.47 %, 9.01%, 11.26%, and 13.21%, respectively.
Overall, 95% of the patients lost weight; 31% lost 20 kg or more, and 77% lost 10% or more of their initial body weight. A total of 97% of the patients experienced a reduction in waist circumference.
“There was no intention to make them lose weight,” Dr. Saad told Renal & Urology News. “The weight loss was never expected. This was found as a side effect of treatment. Some of the men came in for erectile dysfunction treatment.”
In a separate study also presented at this meeting, testosterone replacement therapy was found to significantly improve symptoms of metabolic syndrome associated with testosterone deficiency. Investigators started collecting data in 2004 from 261 patients with late-onset hypogonadism at a single center in Germany. Patients received 1,000 mg of testosterone undecanoate on the first day of the study, at week 6, and then every three months. At each visit, investigators measure subjects' hormone, glucose, and lipid levels, as well as blood pressure (BP).
The mean follow-up was 4.25 years. The prevalence of metabolic syndrome dropped from 56% to 30% after 57 months of treatment. Triglyceride levels decreased in 77% of patients, glucose levels decreased in 67% of patients, and mean arterial pressure decreased in 78% of patients. The average waist circumference shrank by 11 cm.
“When indicated, testosterone treatment is both essential and safe in elderly patients with symptomatic late-onset hypogonadism,” said lead author Aksam Yassin, MD, PhD, Chairman of the Institute of Urology & Andrology in Norderstedt-Hamburg, Germany. “Further analysis is needed to confirm if our findings are due to a direct effect of restoring physiologic testosterone levels.”
Previous research has linked metabolic syndrome to testosterone deficiency. In addition, testosterone deficiency is associated with individual components of metabolic syndrome.
To determine the presence of metabolic syndrome among study participants, investigators used the definition from the International Diabetes Federation. All subjects were diagnosed with the syndrome if they displayed central obesity combined with at least two of the following risk factors: elevated triglycerides levels, decreased high-density lipoproteins, high BP, and excessive blood sugar concentrations.
“Testosterone investigation in elderly patients with health problems is an essential part of men's health practice,” Dr. Yassin said.
Testosterone undecanoate is not yet available in the United States, but it is marketed in Europe, Latin America, Australia, and parts of Asia and Africa. Dr. Saad is an employee of Bayer Pharma, which makes a brand of testosterone undecanoate. Bayer Pharma partially funded Dr. Saad's study in its final two years.