Many have not had elevated ced rate or CRP . A diagnosis of PMR can be that prednisone works. That was my case. My blood tests were normal. here is a quote.

"The erythrocyte sedimentation rate (ESR) is the most sensitive diagnostic study for PMR, although it is not specific. The ESR is frequently elevated and greater than 40 mm/h, but it can exceed 100 mm/h. In 20% of patients, the ESR is mildly elevated or, occasionally, normal, which may occur in patients with limited disease activity. In these cases, diagnosis is based on rapid positive response to low-dose prednisone (10-15 mg/day)."
https://www.uspharmacist.com/article/polymyalgia-rheumatica-a-severe-self-limiting-disease.