A Syndrome of Vitamin D3 Deficiency/Fibromyalgia/Hyperparathyroidism Mimicking Rheumatoid Arthritis, a Clinical Prospective Study

Objectives: Rheumatoid arthritis is sometimes misdiagnosed for other diseases, like psoriatic arthritis, erosive OA, viral arthritis, reactive arthritis, IBD arthritis, Lyme’s disease, and palindromic rheumatism. Secondary hyperparathyroidism was not included in the differential diagnosis of RA, though it sometimes presents with joint pains and tenderness, and even arthritis. Fibromyalgia is a psychosomatic disorder characterized by chronic widespread pain and tender areas. Mimicry of some manifestations of these diseases sometimes results in misdiagnosis as RA. Methods: Two hundred patients previously diagnosed as RA from outpatient clinics in Al-Azhar Faculty of Medicine, attended as not responding to medical treatment of RA. All patients were subjected to a re-evaluation of disease activity including HAQ, and DAS 28, CDAI, and SDAI. Also, we measured serum vitamin D3, PTH, total and ionized Calcium, Phosphorus, Uric acid, ACPA, and other routine lab. All patients were exposed to various radiological imaging modalities. Results: Cases not responding to RA treatment were reevaluated and were found to have a syndrome of fibromyalgia associated with vitamin D3 deficiency and secondary hyperparathyroidism. Conclusions: Fibromyalgia/Hyperparathyroidism syndrome is an underdiagnosed disease, which results from chronic vitamin D3 deficiency. SHPT can cause bone erosions, which are mostly shaggy in appearance and distributed in the radiocarpal, radioulnar, metacarpophalangeal and distal interphalangeal joints, in contrast to that which predominate proximal IP joints of rheumatoid arthritis. Radiology of FM/HPT syndrome patients revealed a sign of spur-like excrescences in terminal finger tufts unilaterally or bilaterally, which we think is pathognomonic.