How is mixed connective tissue disease diagnosed (MCTD)?
A diagnosis can be difficult to make because the three conditions (SLE, scleroderma, and polymyositis) that can be seen in MCTD usually occur one after the other over a long period of time, rather than at the same time. It may take several years to make an accurate diagnosis of MCTD.
There are 4 features that point to MCTD rather than another connective tissue disorder:
- High concentrations in blood tests of a particular antibody called anti-U1-RNP (ribonucleoprotein).
- An absence of the severe kidney and central nervous system problems often found in SLE patients.
- Severe arthritis and pulmonary hypertension, which may not be found in either SLE or scleroderma patients.
- Raynaud phenomenon, and swollen hands or puffy fingers, which occur in only about 25% of SLE patients.