Increased serum alkaline phosphatase activity in ankylosing spondylitis.

Abstract

SUMMARY Raised serum alkaline phosphatase (AP) levels were found in 13 of 76 patients (17 %) with ankylosing spondylitis (AS), and 1 1 of these 13 underwent further investigation to determine the origin of the increased enzyme activity. Three had levels within the normal reference range on re-estimation, and, of the remaining 8, AP isoenzyme studies indicated an increased liver fraction in 6. Serum gamma-glutamyl transpeptidase (GGT) was raised in only 3 patients. Increased AP activity did not appear to be directly related to disease activity or to drug therapy. These findings confirm the occurrence of increased serum AP activity in AS but challenge a previously reported suggestion that bone is the source of the increased enzyme.The serum level of alkaline phosphatase (AP) may rise in a variety of inflammatory rheumatic diseases.' 2 The source of the increased enzyme activity is usually the liver,`-4 but it has been suggested that it arises from bone in ankylosing spondylitis (AS).' We have investigated the prevalence of raised AP in AS and attempted to determine the origin of the increased enzyme activity by isoenzyme studies and by reference to other liver enzymes, specifically alanine transaminase (ALT) and gamma-glutamyl transpeptidase (GGT). Patients and methodsSixty-seven men and 9 women, aged 18-71 years, with AS as defined by the New York criteria, were assessed clinically, haematologically, and biochemically. Five had associated psoriasis, 2 Reiter's disease, and 4 chronic inflammatory bowel disease. The mean duration of spondylitic symptoms was 14-9 years.The initial laboratory investigations included haemoglobin, full blood count, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and a serum biochemical screen for calcium, phosphate, AP, total protein, albumin, bilirubin, and ALT. Repeats of these tests with additional AP isoenzyme studies and estimation of GGT were performed on patients found to have AP levels above 13 King-

Regulation of osteoblasts by alkaline phosphatase in ankylosing spondylitis

“…The strength of our study compared to previous studies evaluating ALP in AS lies in the relatively large sample size ALP level and expression were also higher in our studies based on multiple experimental methods. The potential limitation of our study is that only total ALP was analyzed, although it can be divided into various types as aforementioned.…”

“…ALP offers a biochemical marker of bone formation that can be used to assess osteoblastic activity. In particular, clinical reports suggest that elevated serum ALP level is closely related to disease activity . However, the molecular mechanisms responsible for osteoblast differentiation or its association with AS have not been completely defined.…”

Evidence of impaired cartilage/bone turnover in patients with active ankylosing spondylitis.

“…24 March 1995 Patients and methods The study was approved by the University of Giessen ethics committee, and all participants gave informed consent.…”

Serum osteocalcin and vitamin D metabolites in patients with ankylosing spondylitis.

“…A dissociation of alkaline phosphatase and osteocalcin as found in our patients with AS has also been reported by others. 19 23-25 It can be the result of a major hepatic fraction of alkaline phosphatase isoenzyme as reported by Sheehan et al 22 We could not find increased y glutamyl transpeptidases in the five patients with increased alkaline phosphatase, however. Laboratory values of the two patients receiving NSAIDs did not differ significantly from the rest of the studied group, except for an increased ESR.…”