The level of visit is not determined by the diagnosis. It is a contributing factor in the medical decision making as well as the overarching criteria of medical necessity, but it is not soley what you use to determine the levels. Sure, a viral illness might often be a level 3, but that does not mean it's a level 3 because it's a viral illness. Outpatient coding is based on:
1) Number and complexity of problems.
2) Amount/complexity of data.
3) Risk of complications/morbidity/mortality.
Problems: You are stating it is an acute illness with systemic symptoms. That is level 4 for number/complexity of problems
Data: Ordering 2 tests is a level 3. If any other testing were ordered/reviewed, you could have level 4. Note: often in pediatrics, you will also have an independent historian (parent) as a child may not be able to accurately relay when symptoms started, what their temperature was, etc. It is important for this to be documented, and if so, can be counted. That would be level 4 for data if 2 tests and an independent historian.
Risk: Without a prescription or other treatment, it would be difficult to state this is moderate risk. If no prescription, no additional factors, risk is level 3. If the child also has other conditions (asthma for example), and the clinician notes to continue use of inhaler as needed, that would be level 4.
You need 2 of 3 (problems, data, risk) to meet/exceed the level.
Sometimes using time is a good alternative to MDM. My personal opinion is that for almost all patients, a clinician with competent staff can meet the levels quicker than the time guidelines. Some patients, some clinicians, some specialties are exceptions, but it is an option.