Friday May 11, 2007
Hypokalemia and Hypertension !
Interesting article published this week in The New England Journal of Medicine: Sodium and Potassium in the Pathogenesis of Hypertension. Just to quote few lines from article:
"........Numerous studies show an adverse effect of a surfeit of sodium on arterial pressure. By contrast, potassium, the main intracellular cation, has usually been viewed as a minor factor in the pathogenesis of hypertension. However, abundant evidence indicates that a potassium deficit has a critical role in hypertension and its cardiovascular sequelae.......Population studies have shown an inverse relation of potassium intake to blood pressure, the prevalence of hypertension, or the risk of stroke.... After adjusting for potentially confounding variables, the INTERSALT (The International Study of Salt and Blood Pressure) researchers estimated that a decrease in potassium excretion by 50 mmol per day was associated with an increase in systolic pressure of 3.4 mm Hg and an increase in diastolic pressure of 1.9 mm Hg............ A high-potassium diet and increases in serum potassium, even within the physiologic range, cause endothelium-dependent vasodilatation by hyperpolarizing the endothelial cell through stimulation of the sodium pump and opening potassium channels....The central actions of changes in the concentrations of sodium and potassium in the cerebrospinal fluid and of an excess of sodium and a deficit of potassium in the body are probably mediated by changes in the activity of the neuronal sodium pump and the renin–angiotensin system in the brain. These changes alter sympathetic outflow, which then causes directional changes in blood pressure. Baroreceptor sensitivity is depressed by potassium depletion and restored by potassium supplementation.......In its 2002 advisory, the coordinating committee of the National High Blood Pressure Education Program identified both a reduction in dietary sodium and potassium supplementation as proven approaches for preventing and treating hypertension. The Institute of Medicine...also advises adults to consume at least 120 mmol of potassium per day (approximately 4.7 g of potassium per day, which is about twice the current U.S. average)......"
Reference: click to get abstract
Sodium and Potassium in the Pathogenesis of Hypertension - Volume 356:1966-1978 , May 10 2007
1 comment:
Hypertension, When to Treat?
The 18 year Framingham Blood Pressure study found increased risk of heart disease and death in people with increased blood pressure 140 to 160, and even more risk above 160.
If you examine the original data from the Framingham study, you will find computer smoothing of the data as published in the medical journals. This gives a smooth gradual line of increasing mortality as blood pressure goes up between 140 and 160. This is called the Linear Model. However, if you examine the raw data, as S. Port did as published in Lancet 1/15/2000, you will find a non-linear threshold of increased risk above 160 systolic, and no increased mortality below 160.
For a more complete review of this controversy in Blood Pressure guidelines, see my newsletter
Blood Pressure Pills for Hypertension, When to Treat? by Jeffrey Dach MD
Jeffrey Dach MD
Post a Comment