Normal ESR with elevated CRP is seen in some cases of
Investigations in PMR and GCA The typical laboratory abnormality is an elevated ESR, often with a normochromic, normocytic anaemia. CRP may also be elevated and abnormal liver function can occur. Rarely, PMR and GCA can present with a normal ESR. More objective evidence for GCA should be obtained whenever possible. There are three investigations to consider: temporal aery biopsy, ultrasound of the temporal aeries and 19fluorodeoxyglucose positron emission tomography (19FDG PET scan). Characteristic biopsy findings are fragmentation of the internal elastic lamina with necrosis of the media in combination with a mixed inflammatory cell infiltrate. Diagnostic yield is highest with multiple biopsies and multiple section analysis (to detect 'skip' lesions). A negative biopsy does not exclude the diagnosis. On ultrasound examination, affected temporal aeries show a 'halo' sign. A strongly positive 19FDG PET scan is highly specific but sensitivity is low. Caution is needed in interpreting weakly positive images. Low-grade vascular uptake may occur in atheromatous aerial disease. Ref Davidsons 23e p1042
RA
Polymyalgia rheumatica
SLE
Systemic sclerosis
Miscellaneous