Thank you for your inquiry.
In answer to your first question, the National Jewish Health Laboratory does have the test (Catalog Number M11, entitled Precipitin Penicillium Mix IgG).
In answer to your second question, since what you would be dealing with is an alveolitis (the alternative name for hypersensitivity pneumonitis is extrinsic allergic alveolitis), one would clearly expect a defect in the DLCO. Thus, if you have not done complete pulmonary functions with DLCO, I believe that would be in order. If the DLCO is normal, it mitigates strongly against the diagnosis unless the disease is at its very earliest phase. But even at the earliest phase, the DLCO usually decreases with exercise. You might also, therefore, consider a pulse ox, both at rest and with exercise, in your office. Finally, a high resolution computed tomography scan would almost universally be abnormal because alveolar changes, even at the earliest phase, should be present.
Finally, as you mentioned earlier about IgG anti-penicillium, precipitin anti-penicillium (IgG or IgM), although very sensitive, are also found in many patients without disease who are exposed. So they are highly sensitive, but not very specific.
Thank you again for your inquiry and we hope this response is helpful to you.
Phil Lieberman, M.D.