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Growth hormone may explain higher blood pressure risk in African Caribbean people
Increased levels of a growth factor that affects the kidneys may explain why African Caribbean people are more likely to develop high blood pressure and are more suspectible to salt's blood pressure raising effects. It raises hopes that new drugs may be developed that could target the actions of this growth hormone.
Research has found that African Caribbean people are more sensitive to the blood pressure raising effects of salt and are four times more likely to develop kidney disease than their white counterparts. This American study looked at levels of a growth hormone called Transforming Growth Factor B1 (TGF-B1) to see if it was linked to blood pressure, salt sensitivity, kidney problems, weight, and the risk of developing diabetes (metabolic syndrome).
TGF-B1 levels higher in African Caribbean people
When the TGF-B1 levels of 186 African Caribbean people and 147 white people were measured, it was found African Caribbean people had significantly higher levels of the growth factor:
- African Caribbean people with high blood pressure had the highest levels of TGF-B1 - 42ng/ml
- Healthy African Caribbean people without high blood pressure had the next highest TGF-B1 levels - 40ng/ml
- White people with high blood pressure had slightly lower TGF-B1 levels - 40ng/ml
- Healthy white people without high blood pressure had the lowest TGF-B1 levels - 39ng/ml.
These findings suggest that healthy African Caribbean people may be at a higher risk of high blood pressure and kidney disease than healthy white people and white people with high blood pressure.
TGF-B1 levels and blood pressure
There appeared to be a weak association between higher blood pressure and TGF-B1 levels for both groups. But the association was much stronger for African Caribbean people than for white people.
TGF-B1 levels and kidney problems
The study's results suggest that TGF-B1 increases salt retention by the kidneys (which increases blood pressure) and raises blood pressure in the kidneys themselves - increasing the risk of future kidney problems.
TGF-B1 and other risk factors for high blood pressure and kidney disease
It was also found that higher levels of TGF-B1 were associated with higher body mass index (BMI) levels and increased risk of developing metabolic syndrome (which can lead to diabetes). Increased body mass (or increased body fat) is known to raise blood pressure, while metabolic syndrome (and diabetes) can damage the arteries and increase the risk of heart disease.
In summary, the research reveals that TGF-B1 may be responsible for African Caribbean people's raised risk of high blood pressure, kidney disease and increased sensitivity to salt. This finding offers a new potential area for treatment - in creating medicines that could counter this effect. However, will take many years of research and testing to formulate such medications. At the moment, the best advice is to reduce salt intake as much as possible and to keep to a healthy weight (or lose weight if needed).
Manikkam Suthanthiran, Linda M Gerber, Joseph E Schwartz, Vijay K Sharma, Mara Medeiros, RoseMerie Marion, Thomas G Pickering and Phyllis August. Circulating transforming growth factor-1 levels and the risk for kidney disease in African Americans. Kidney Int 76: 72-80; advance online publication, March 11, 2009; doi:10.1038/ki.2009.66
Soo Bong Lee, Keizo Kanasaki and Raghu Kalluri. Circulating TGF-1 as a reliable biomarker for chronic kidney disease progression in the African-American population. Kidney International 2009; 76: 10–12. doi:10.1038/ki.2009.130
Topics: Research, High blood pressure