Correct!
5. None of the above
A positive rheumatoid factor occurs when antibodies are formed against the Fc portion of IgG (also an antibody) (1). Although a rheumatoid factor is elevated in rheumatoid arthritis, it can be seen in a variety of other rheumatologic diseases and nonrheumatologic disorders including cancer, chronic infections, inflammatory lung diseases (sarcoidosis, tuberculosis, idiopathic pulmonary fibrosis), mixed connective tissue disease, Sjögren's syndrome and systemic lupus erythematosus. To add even more confusion, some healthy individuals also have a positive rheumatoid factor (5% increasing to 20% over the age of 65 years).
Her pulmonary function tests show mild obstruction with a FEV1/FVC ration of 65% despite her FEV1 being within the normal range. Her diffusing limit for carbon monoxide (DLco) is also slightly decreased 75% of predicted (normal >80% predicted). Although these abnormalities might be dismissed in an otherwise normal healthy subject, they may be significant in a patient complaining of dyspnea.
Lastly, her chest x-ray does not show increased interstitial markings but does show hyperinflation (> 10 posterior ribs in the midclavicular line above the diaphragm).
Which of the following should be done next? (Click on the correct answer to proceed to the fourth of five pages)