B-type Natriuretic Peptide in the Non-Cardiac Pediatric Patient

B-type Natriuretic Peptide (BNP) is a hormone that is made by the pumping chambers of the heart. The BNP level can be measured by a blood test and is used as a marker for heart problems in adults. Deciding if a child has a heart problem or a lung problem can be very difficult, especially in infants. Several studies have demonstrated that BNP levels are elevated when children have heart disease. The overall goal of the study is to be able to prove that obtaining BNP levels in pediatric patients can be used to identify heart problems. We already know that kids with heart problems have high BNP levels (\>200pg/ml). We need to prove that children who come to the Emergency Department for non-cardiac problems still have normal BNP levels (\<100pg/ml, slightly higher in the newborn population). This will be done by comparing BNP levels with the final diagnosis made by the ED physician.