by
Mohamed Elseginy , Marketing/ Advertisement salesman , Motor Time Auto-newspaper
This isn't really something to be answered, each disease or disorder category has its own way to reach their diagnoses, some have a specific work up, while some are diagnosed by exclusion.
Most of diseases are diagnosed by the presentation and a simple examination, which gives the provisional diagnosis or the differential, then according to the disease it needs more work up.
For infections the best and most accurate is lab work, like cultures to detect the type of organism
For tumors its biopsy with all its different types, followed by radiological investigation for staging the tumor.
Auto-immune diseases are the by lab works and detecting auto-anti bodies in the blood. And so on
