No wonder you are concerned. They have apparently seen some markers in your blood that indicate "some abnormality" but I would think it is most likely not a life-threatening situation or they would be pursuing a better diagnosis. Not being a doctor or hematologist, but only a medical consumer myself, I cannot imagine doing anything else.
What did they tell you about "what it is not"? If they did not tell me what their tests ruled out, I would certainly look back at the paperwork from the visit, or call and ask for an explanation.
Have you asked for a better explanation, either from your rheumatologist or primary providr?
Sue