Amyloidosis

Amyloidosis is the generic term for a heterogeneous group of disorders characterised by the common finding of amyloid deposition. The various acquired and hereditary syndromes are classified according to the identity of the respective amyloid fibril sub-unit protein. Systemic amyloidosis and some local forms are progressive diseases that are frequently fatal. The diagnosis of systemic amyloidosis is only occasionally suspected on clinical grounds alone, and is more often considered when an associated disorder such as a chronic inflammatory disease or monoclonal gammopathy is present. No blood test is diagnostic of amyloidosis but routine haematological and biochemical investigations have important roles in defining the underlying metabolic disturbance and evaluating function of affected organs. The diagnosis can only be confirmed by demonstrating the presence of tissue amyloid deposits. Traditionally this required histology but the recent introduction of labelled serum amyloid P component scintigraphy is a specific alternative that provides a quantitative macroscopic whole body survey of amyloid deposits. No treatment specifically causes the resolution of amyloid but therapy which reduces the supply of amyloid fibril precursor proteins can improve survival and preserve organ function. Major regression of amyloid occurs in at least a proportion of such cases suggesting that clinical improvement reflects mobilisation of amyloid.