The axial spondyloarthritis clinical phenotype in idiopathic hypoparathyroidism: critical review of concept that muscular hypercontractility can induce enthesopathy lesions
A.T. Masi1, L.C. Jorgenson2, S. Ilahi3
- Department of Medicine, University of Illinois College of Medicine at Peoria (UICOMP), Peoria, IL, USA. firstname.lastname@example.org
- Transitional Resident, University of Illinois College of Medicine at Peoria (UICOMP), Peoria, IL, USA.
- Family Medicine Resident, Niagara Falls Memorial Medical Center, Niagara Falls, NY, USA.
2021 Vol.39, N°6
PI 1422, PF 1431
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PMID: 34128805 [PubMed]
Accepted : 26/04/2021
In Press: 08/06/2021
Idiopathic hypoparathyroidism (iH-PoPT) is a rare condition infrequently associated with axial spondyloarthritis (SpA) which may mimic ankylosing spondylitis (AS). Axial SpA is a unifying clinical term for chronic inflammatory spinal disorders, although biomechanical factors may play a role. The primary objective of this review is to critically describe the iHPoPT/SpA phenotype defined by established criteria and its differentiation from AS. Five databases were comprehensively searched without time limit to retrieve 14 (11M, 3F) iH-PoPT/SpA cases. Their demographic, clinical, laboratory, radiographic, and HLA-B27 status were compared to two national series of AS patients. Mean (SD) onset age of musculoskeletal symptoms [32.5 (9.7)] was significantly older than 943 German AS patients [25.1 (8.5), (p=0.004)] and 842 Spanish AS patients [26.1 (9.7), (p=0.030)]. Radiographic lesions of iHPoPT/SpA differ morphologically from skeletal alterations in hyperparathyroid and hypophosphataemic syndromes which often have inadequate bone mineralisation and decreased bone mineral density (BMD). Clinical musculoskeletal manifestations were greater (p<0.001) in iHPoPT/SpA than AS patients at cervical (62 vs. 10%) and hip (85 vs. 22%) localisations, respectively. Typical AS sacroiliac joint structural lesions of erosions and bony bridging were reported in only 1 iHPoPT/SpA case and HLA-B27 was positive in 2 of 10 tested. The iHPoPT/SpA phenotype may be a natural experiment on the novel concept of how chronic hypocalcaemia of iHPoPT causes axial neuromotor hypercontractility and biomechanically induces the rare SpA association. In iHPoPT/SpA, neuromuscular hyper-contractility may predispose to axial radiographic enthesopathy lesions and contribute knowledge on biomechanical contributions and pathways for further research.