In chronic illnesses like lupus the following may occur: Symptoms come and go for months or years before a diagnosis is certain.
Laboratory tests may change over the course of treatment.
You may not know for months whether a prescribed treatment works; it may not work, and it may be necessary to try another medication.
The illness changes from day to day: in treatment trials spontaneous remissions make it difficult to be certain that the treatment worked until the trial has been repeated several times. Your diagnosis may change over time.