Your Voice

January 1, 2009

In the November 2008 pediatric hypertension article, I was surprised to see in the clinical case presentation that the child's blood pressure was not measured off of his methylphenidate, despite the data in Table 2.

Hypertension and stimulants

In the November 2008 pediatric hypertension article, I was surprised to see in the clinical case presentation that the child's blood pressure was not measured off of his methylphenidate, despite the data in Table 2.

I have often seen increased blood pressure and/or tachycardia in children who are on stimulant medications. I have had to discontinue them when hypertension is a side effect, although some have been able to tolerate dexmethylphenidate (Focalin).

Sari K. Friedman, MD

Dear Dr. Friedman, Thank you very much for your letter, and for bringing up two very important topics. It is true that medications used to treat attention deficit hyperactivity disorder (ADHD) can increase blood pressure (BP) and heart rate (HR). Amphetamines and methylphenidate preparations are sympathomimetics, which block the reuptake of norepinephrine and dopamine. Atomoxetine is a non-stimulant medication that acts as a selective norepinephrine reuptake inhibitor. The pharmacological actions of these medications lead to the known cardiac side effects of increased HR and BP.

Interestingly, the increase in HR and BP found with these medications when systematically studied are minimal, and not clinically significant. On average, HR increased by only 1 to 2 bpm, and systolic and diastolic BPs by 3 to 4 mm Hg1 at most, effects confirmed on 24-hour ambulatory BP monitoring.2 Some studies have even found no effect on HR or BP compared to placebo.3,4

This evidence, along with the increasing prevalence of hypertension (HTN) in children, make it difficult to attribute a child's HTN to ADHD medications, without an evaluation that includes an assessment of electrolytes and kidney function (as described below for obese children).

To use the example of the child presented in the article, if we were to "eliminate" this potential effect on his measurements by subtracting 4 mmHg, he would still be considered hypertensive, as his BP would remain at the 95th percentile. In addition, if ADHD therapy is working well, many children and families would find it difficult to undergo a trial off of ADHD medications in order to obtain serial BP measurements.

Lastly, obesity is also on the rise in children, and is an important cause of HTN. That being said, primary HTN, which includes obesity-related HTN, should be a diagnosis of exclusion. Obese children should also undergo the same work-up as suggested above, and only children with pre-hypertension (BPs between the 90th and 95th percentile) should be allowed to initiate lifestyle medications prior to a work-up.

If no secondary cause is identified in an obese child after obtaining a comprehensive metabolic panel, complete blood count, urinalysis, and renal ultrasound, the work-up can often stop there. This is particularly true if the child is older, post-pubertal, African American, or has a family history of HTN, as these children are more likely to have primary HTN.5 Weight loss is an effective means of lowering blood pressure, but it is also a difficult endeavor for most children and families. Lifestyle modifications, including attempts at weight loss, are an important adjunct to anti-hypertensive therapy in these children. Once weight loss occurs, a trial off of medications can be attempted.

Tammy M. Brady, MD, MHS Johns Hopkins School of Medicine, Baltimore