Single center, open-label, non-randomized study to assess the pharmacokinetic profile of methylprednisolone in healthy children 2-20 years of age admitted for asthma exacerbation.

This is a prospective study aiming to characterize the pharmacokinetics of methylprednisolone in obese and non-obese children hospitalized for asthma, and to build a metabolomic profile for each cohort. The primary hypothesis is that the obese cohort will have increased methylprednisolone clearance compared to the non-obese cohort. The secondary hypothesis is that the obese cohort will have decreased amounts of 11-β-hydroxysteroid dehydrogenase in the serum which will correlate to abnormalities in steroid clearance. The tertiary hypothesis is that the obese cohort will have increased levels of branched chain amino acids and inflammatory markers which will correlate to disease severity.

Inclusion Criteria:

1. Age between 2 years and 20 years inclusive
2. Written informed consent provided by a parent or legal guardian
3. Admitted to Duke Children's Hospital for primary reason of asthma exacerbation (and treated with methylprednisolone)
4. BMI-percentile greater than 95th for obese subjects and BMI less than 95th percentile for non-obese subjects

Exclusion Criteria:

1. Patients with suspected liver failure, renal failure, sepsis, or cardiopulmonary instability deemed by the PI.
2. Receiving any extracorporeal life support including extracorporeal membrane oxygenation, ventricular assist devices, and renal replacement therapy at enrollment
3. Any condition or circumstance that, in the opinion of the investigator, would compromise the safety of the participant or the quality of the data.

Children and young adults 2-20 years of age who are admitted to Duke Hospital for primary reason of asthma exacerbation and are treated with methylprednisolone.