Catecholamine alterations in pediatric obstructive sleep apnea: effect of obesity
Ayelet B Snow1, Abdelnaby Khalyfa, Laura D Serpero
1Division of Pediatric Sleep Medicine and Kosair Children's Hospital Research Institute, Department of Pediatrics, University of Louisville, Louisville, KY 40202, USA.
Insights
Children with obstructive sleep apnea (OSA) show higher morning urine norepinephrine and epinephrine levels, correlating with disease severity. Obesity did not influence these elevated catecholamine levels in children.
Area of Science:
- Pediatric Sleep Medicine
- Cardiovascular Physiology
- Biochemistry
Background:
- Obstructive sleep apnea (OSA) is linked to increased sympathetic activity and elevated urinary catecholamines in adults.
- Urinary catecholamine excretion patterns are also altered in obese individuals.
- The relationship between OSA severity, obesity, and catecholamine levels in children remains unclear.
Purpose of the Study:
- To investigate the correlation between morning urinary catecholamine levels and the severity of obstructive sleep apnea (OSA) in children.
- To determine if obesity influences urinary catecholamine levels in pediatric OSA patients.
- To explore gene expression patterns related to catecholamine pathways in children with OSA.
Main Methods:
- Overnight polysomnography was performed on children referred for habitual snoring.
- First morning voided urine samples were analyzed for norepinephrine, epinephrine, and dopamine concentrations, corrected for creatinine.
- Quantitative real-time PCR was used to analyze gene expression of catecholamine-relevant genes in a subset of participants.
Main Results:
- Children with OSA exhibited significantly higher urinary norepinephrine and epinephrine levels compared to non-OSA habitual snorers.
- Positive correlations were observed between norepinephrine and epinephrine levels and polysomnographic indices of OSA severity.
- Urinary catecholamine levels were not significantly affected by the degree of obesity in the studied children.
Conclusions:
- Morning urinary norepinephrine and epinephrine levels are elevated in children with OSA and correlate with disease severity.
- Gene expression data support increased catecholamine bioavailability in pediatric OSA.
- The observed alterations in sympathetic activity in pediatric OSA appear independent of obesity.
Study Objectives:
Obstructive sleep apnea (OSA) elicits increased sympathetic activity in adults and increased urinary catecholamines. Moreover, urinary catecholamine excretion is altered in obese patients. We hypothesized that morning urine catecholamine levels would be correlated with the severity of obstructive sleep apnea and degree of obesity in children.
Methods:
Children referred to the pediatric sleep center for habitual snoring underwent overnight polysomnography, and the first morning voided urine sample was collected. Urinary concentrations of norepinephrine, epinephrine and dopamine were measured and corrected for creatinine levels. In a subset of children, blood samples were drawn and gene expression of catecholamine-relevant genes analyzed by quantitative real-time PCR.
Results:
One hundred fifty-nine children were recruited and completed the protocol. Children with OSA had significantly higher urinary norepinephrine and epinephrine levels, but not dopamine, compared to habitual snorers (norepinephrine: 40.1 +/- 24.7 ng/mg creatinine vs. 31.6 +/- 16.2 ng/mg creatinine, P < 0.01; epinephrine: 6.4 +/- 10.5 ng/mg vs. 4.5 +/- 0.5 ng/mg, P < 0.01). There was a positive correlation between norepinephrine and epinephrine values and polysomnographic indices, but no effect of obesity on catecholamine levels. In addition, expression of several of the major genes involved in synthesis and transport of catecholamines, as well as in selected receptors were compatible with increased bioavailability of catecholamines.
Conclusions:
In children with OSA, morning urinary norepinephrine and epinephrine levels are significantly higher than those without OSA, and correlate with the severity of the disease. Gene expression patterns are in agreement with such findings. Urine catecholamine levels do not appear to be influenced by the presence of obesity. Thus, altered sympathetic activity in OSA patients appears to occur independently of the presence of obesity.
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