Female 37 complement c3 /c4 test normal,double stranded dna negative. strong positive rnp .ana titer 3.6 inflammation markers normal.systemic enquiry no symptoms of connective tissue disease dermatologist could not diagnose ct disease or lupus ,true?

You did not state what the symptoms this 37 year old woman has. You mentioned dermatologist so I assume her main symptom is skin problem. Connective tissue disease is strongly suspected with a strong positive RNP titer. Discoid lupus or systemic lupus erythematosus (SLE) is very less likely with negative dsDNA antibody.

1st. thing to remember is:Doctors don’t treat lab tests,but patients.2nd. URNP is only one of the ENAs.If others negative too, lupus is less likely.3rd.URNP is + in Mixed Connective Disease(when dsDNA antibodies and Sm antibodies are not detectable), but in 50% of Lupus patients too.Bottom line: All too complex,trust your Doctor or look for a second opinion of another specialist to see the lesions

True, we need to know what symptoms this patient presented with? (butterfly rash? petechiae, vasculitis? raynaude's?) Positive RNP is not diagnostic and needs to be interpreted in context.