Alveolar hemorrhage is an uncommon event that is associated with sever
al underlying disorders, many of which are immunologically mediated. C
areful evaluation of basic laboratory tests, extrapulmonary physical f
indings, and serology usually leads to the correct diagnosis. Signific
ant overlap exists, however, and pathologic (especially immunopatholog
ic) evaluation of pulmonary or renal biopsies may be necessary. An acc
urate diagnosis is essential because treatment is best when directed a
t the underlying diagnosis. Supportive therapy may be needed until the
underlying disease is diagnosed and specific therapy is initiated.