“Hypertension” is the fancy word for high blood pressure. Blood pressure is the measure of how much pressure it takes the left ventricle of the heart to squeeze the blood out (the top number, or systolic pressure) and the pressure inside the left ventricle of the heart when the heart is relaxed (the bottom number, or diastolic pressure).
“Normal blood pressure” changes throughout life, and is based on sex, age, and height. Most health care providers use the blood pressure reference provided by the National Institute of Health (NIH) to see if a child’s blood pressure is normal, and, as a general rule, 120/80 is the top limit for a normal blood pressure.
High Blood Pressure Causes
One of the causes of high blood pressure is having a large blood volume (the amount of blood and fluid in the body’s circulatory system which is pumped by the heart). This is why people with high blood pressure are put on “diuretics,” or water pills to decrease blood volume. Diuretics cause increased urination, which gets rid of fluid in the body, which decreases the blood volume, giving the heart less blood to pump, requiring less pressure to pump, thus lowering the “blood pressure.” Blood volume can be increased by a diet high in salt – salt in the gut attracts water, and more water entering the body systems increases the blood volume. This is why people with high blood pressure are encouraged to decrease or limit their salt intake.
Steroids & Salt Intake
Recently, the issue of whether it is necessary for children who take “glucocorticoids” (prednisone or deflazacort) to limit their sodium/salt intake has come up. It is well known that taking steroids (prednisone or deflazacort) can cause glucocorticoid-induced hypertension. After consulting with five major programs (Columbus, Cincinnati, Iowa City, Seattle, and Baltimore), we have developed the following suggestions. (As always, if you have questions specific to your child, please ask your health care provider.)
While children taking glucocorticoids rarely develop hypertension, it has been shown that approximately 20% of patients treated with glucocorticoids will develop glucocorticoid-induced hypertension[i]. What is less clear is why. A recent review article [ii] suggests that there are several interactions that occur between the glucocorticoids and glucocorticoid receptors in body tissues (central nervous system, blood vessels, kidney, fat, and liver).
There is little evidence showing that increased salt and water in the body cause glucocorticoid-induced hypertension [iii]. In fact, studies have been done, giving patients who take glucocorticoids, spirololactone (which blocks the body from holding salt/sodium and water) to see if there was less hypertension; there was no reduction in the incidence of hypertension [iv]. Absorbing too much salt/sodium does not seem to cause or effect glucocorticoid-induced hypertension [v].
Given these findings, is it really necessary to limit your child’s salt intake?
Managing Factors That Cause High Blood Pressure
As stated above, children who take glucocorticoids may be at increased risk for developing high blood pressure. Given this fact, it is important to manage other factors, which may also cause high blood pressure. These include:
I hope this helps address the Salt, Steroids and Duchenne issue. As with most things, moderation is key!
[ii] Goodwin JE, Geller DS. Glucocorticoid-induced hypertension. Pediatr Nephrol (2012) 27:1059-1066.
[iii] Zhang Y, Whitworth JA. The role of nitric oxide: redox Imbalance in glucocorticoid-induced hypertension. Pp.129-146. NOVA Publishers.
[iv] Mangos GJ, Whitworth JA, Williamson PM, Kelly JJ (2003) Glucocorticoids and the kidney. Nephrology (Carlton) 8:267–273
[v] Li M,Wen C, Fraser T,Whitworth JA (1999) Adrenocorticotrophininduced hypertension: effects of mineralocorticoid and glucocorticoid receptor antagonism. J Hypertens 17:419–426