Researchers have developed a new use for a common blood test, which could provide potentially life-saving treatment for heart failure.
According to the study, published in the journal Frontiers in Physiology, biomedical experts believe that half of heart failure patients likely have low levels of the thyroid hormone T3 in their cardiac tissue.
A growing number of studies suggest that low cardiac T3 may significantly contribute to a patient's symptoms and underlying heart dysfunction.
The symptoms of low cardiac T3 are also virtually indistinguishable from other conditions that lead to heart failure, suggesting that a significant number of underlying heart dysfunction and heart failure symptoms may actually be caused by a treatable T3 hormone imbalance.
"Despite this treatability, clinicians are hesitant to prescribe T3 to heart patients, as too much of the hormone could accidentally trigger an irregular heartbeat," the study authors from New York Institute of Technology (NYIT) in the US, wrote.
In addition, no method has yet been identified to titrate, or continually measure and adjust, for the dosage of T3 needed to safely restore the heart's thyroid hormone function.
Now, an existing biomarker called brain natriuretic peptide (BNP) may provide the much-needed solution, the researchers said.
In medicine, biomarkers are biological molecules found in a patient's blood, fluid, or tissue sample that can indicate whether a disease or condition is present.
They can also be used to see how well the body responds to treatments.
During heart failure, the heart will secrete higher levels of the biomarker BNP into blood, a key indication that the heart disease is worsening.
The researchers hypothesised that by analysing a patient's BNP levels in response to added T3, clinicians could titrate for just the right dosage required.
Using rat models of heart failure caused by low T3 and heart attack, the researchers tested their theory, examining changes in BNP, cardiac function, and heart failure genes after T3 treatment.
For the first time, they discovered through a simple blood test, not an extensive, invasive procedure, that T3 could be adjusted to safely restore cardiac hormone balance.
In addition, because heart patients routinely undergo BNP and thyroid hormone testing, these widely used biomarkers could be easily monitored from blood tests.
"The results were remarkable, suggesting that serum BNP levels can be used to titrate the volume of T3 required," said study researchers Martin Gerdes from NYIT.
"When T3 treatment led to a reduction in serum BNP levels, this was associated with improved cardiac function and reversal of these heart failure genes," Gerdes added.