Thanks for your question. When labs are done the one thing that doctors are looking for are abnormally high or abnormally low values. A lab result of 3.99 when normal is 4.2 is not something that is cause for concern-- keep in mind that lab values are ranges. This is likely why all of her values were "normal".
Serious side effects of Ativan include:
persistent, fine tremor or inability to sit still
difficulty breathing or swallowing
severe skin rash
yellowing of the skin or eyes
If you have questions as to why she may have ended up in the ER, please consult with her doctor since s/he is the best person to answer this.