Lupus is a difficult diagnosis to make, even when obvious symptoms are present. Most tests that are done to determine this condition are blood tests - the ANA test, white blood cell count, etc. However, you have to have something like 5 symptoms of 8 probable symptoms for a doctor to make the diagnosis.
I first presented symptoms when I was around 21 (I am 50 now). The doctors suspected it, but could not definitely say it was lupus. I lived a pretty symptom-free life for many years. Then in 2003, I got meningitis, and was hospitalized for 2 weeks. That was most likely triggered from my compromised immune system. Then in 2005, I developed a blood clot on my kidney. Again, I was hospitalized for 2 weeks and have been on blood thinners since then. Hopefully no other life-threatening events will occur. I have systemic lupus, which affects your body's organs and systems. I never had the 'butterfly rash'. The discoid lupus is the version that affects the skin and most often cause skin rashes.