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The axial spondyloarthritis clinical phenotype in idiopathic hypoparathyroidism: critical review of concept that muscular hypercontractility can induce enthesopathy lesions

1, 2, 3


  1. Department of Medicine, University of Illinois College of Medicine at Peoria (UICOMP), Peoria, IL, USA.
  2. Transitional Resident, University of Illinois College of Medicine at Peoria (UICOMP), Peoria, IL, USA.
  3. 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]

Received: 15/02/2021
Accepted : 26/04/2021
In Press: 08/06/2021
Published: 26/11/2021


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.

Rheumatology Article