A new study found that sex hormone-binding globulin (SHBG) could be a biomarker of a higher risk of cardiovascular diseases in men, Health Day reported. When scientists compared the low concentration of testosterone and low concentration of SHBG, they found that the former is not linked to cardiovascular diseases in men, but the latter is associated with high incidents of myocardial infarction.
What is Sex Hormone-Binding Globulin?
According to WebMD, sex hormone-binding globulin is a protein found in the blood that binds with certain hormones to control their amount and identify which tissues can have access to these hormones. SHBG is produced in the liver and a small amount in the testes. It is an ancient protein found in all mammals, but the fish also has its version of SHBG.
The three hormones that SHBG binds to are found in both men and women, such as the main sex hormone for males called testosterone, as well as dihydrotestosterone, and estradiol which is a form of estrogen. Testosterone and estrogen are hormones that help develop sexual and reproductive tissues. It is the job of SHBG to move the active versions of these hormones throughout the body.
This protein can vary per person and may change throughout the lifetime. Some factors that affect their normal levels are sex, age, weight, genetics, metabolism. Moreso, certain conditions may result in too low or too high levels of SHBG. Doctors take these factors into consideration to decide whether SHBG levels are in the normal range.
When SHBG levels are low, it could indicate that the person has hypothyroidism, Cushing's syndrome, Type 2 diabetes, cancer in testes, and polycystic ovary syndrome. But too much of the protein could indicate hyperthyroidism, pituitary problems, and Addison's disease.
Low Sex Hormone-Binding Globulin Linked to High Incidents of Heart Attack
Doctors sometimes compare SHBG levels to testosterone levels to estimate how much testosterone the body uses. Problems in the ratio between the two could indicate androgen deficiency and hypogonadism. The new study reveals that low SHBG is associated with myocardial infarction but now low testosterone.
In the study, titled "Associations of Serum Testosterone and Sex Hormone-Binding Globulin With Incident Cardiovascular Events in Middle-Aged to Older Men" published in Annals of Internal Medicine, researchers examined the link between SHBG and serum total testosterone with incidents of cardiovascular diseases among men aged 40 to 69 years old from the UK Biobank cohort.
According to Medical Xpress, the team found that 4.2% of the 210,00 participants researchers followed for nine years had an incident of a cardiovascular event. Low testosterone concentrations were not associated with myocardial infarction, hemorrhagic stroke, ischemic stroke, heart failure, and other major adverse cardiovascular events.
However, they were able to record associations to those diseases in low concentrations of SHBG, especially in myocardial infarction, ischemic stroke, and heart failure. But there were no associations seen for hemorrhagic stroke and major adverse cardiovascular events.
"Men with lower SHBG concentrations have a higher risk for MI but lower risk for HF, indicating a role for SHBG as a biomarker for various cardiovascular risks, independently of total testosterone concentrations," the researchers write.
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