investigations
Last reviewed 07/2021
60-90% of patients are HLA-B27 positive.
During the active phase of the disease the ESR is elevated.
The causative organism may be isolated from urethral fluids, if Chlamydia trachomatis, or faeces, if shigella, salmonella or yersinia.
There may be rising titres of antibodies to these organisms.
The following investigations are of use:
- ESR - increased, in parallel with the clinical course
- CRP - increased, in parallel with the clinical course
- FBC - WBC is elevated (10,000-20,000 /cu mm); mild hypochromic or normochromic anaemia
- serum globulins are increased in long-standing disease