POS1363 CHONDROCALCINOSIS AS PREDICTOR OF DEVELOPMENT OF PRIMARY HYPERPARATHYROIDISM: RESULTS OF THE FOLLOW-UP OBSERVATION
Authors: A. Novikova, M. Elisеev, O. Sheliabina, M. Chikina
Journal: Annals of the Rheumatic Diseases (2021)

Background: The association between chondrocalcinosis and primary hyperparathyroidism (PHPT) is known, but chondrocalcinosis is considered as a late complication of PHPT. Objectives: To investigate whether calcium pyrophosphate crystal deposition is an early clinical sign of PHPT. Methods: The prospective study included 113 patients aged ≥18 years, 42 (37.2%) men and 71 (62.8%) women, with a crystal-verified diagnosis of calcium pyrophosphate crystal deposition disease (CPPD) (McCarty criteria). Exclusion criteria were the presence of other rheumatic diseases with symptoms of arthritis, the presence of hyperparathyroidism (HPT). Patients were examined at their enrollment and over time, the median follow-up was 3.86 [2.07; 8.36] years. The examination of the patients included assessment of anthropometric parameters, information about the affected joints and the time of onset of symptoms. Laboratory tests included determination of the following in blood serum: creatinine (with estimating glomerular filtration rate (eGFR) according to the MDRD formula), total and ionized calcium (Ca and Ca ++ ), phosphorus (P), parathyroid hormone (PTH), vitamin D (25-OH); ultrasound and X-ray investigations of the target joints (hands, knee joints) were made for all patients. Scintigraphy and ultrasound of the parathyroid glands were performed if medically required. Statistica 12.0 package was used for statistical data processing. Results: 113 patients were examined, the average age was 58.4±12.4 years. 10 patients were excluded due to diagnosed HPT at screening. 41 patients dropped out of observation: 5 - died, 36 were not available for dynamic examination. 62 patients were examined in dynamics, 4 (6.5%) of those had HPT. In 1 (1.6%) case, HPT was associated with chronic renal failure, 3 (4.8) patients were diagnosed PHPT. The results of the examination of patients who developed PHPT during screening and in dynamics are presented in Table 1 above. Table 1. Results of patients with PHPT at screening and in dynamics. Сrystals of calcium pyrophosphate in synovial fluid Chondrocalcinosis by ultrasound Chondrocalcinosis by X-ray Convulsions ECG changes (shortening of the QT interval) Arthralgias / arthritis PTH, pg/ml (15,0-65,0) Ca, µmol/l (2.10-2.62) Са ++ , µmol/l (1.10-1.33) vitamin D (25-ОН), ng/ml (30-100) screening / dynamics Рatient А. yes/yes yes/yes not/yes not/not not/not yes/yes 61.6/96.2 2.73/2.67 1.37/1.24 -/31 Рatient В. yes/yes yes/yes yes/yes not/yes not/yes yes/yes 40.7/252 2.63/2.56 1.34/1.77 19.1/14.2 Рatient С. yes/yes yes/yes not/yes not/not not/not yes/yes 26.6/102.4 2.60/2.65 1.25/1.26 -/40 In all three patients, chondrocalcinosis was revealed by ultrasound and Сrystals of calcium pyrophosphate in synovial fluid during the screening examination, in one patient chondrocalcinosis was revealed by X-ray. In two out of three cases, the level of serum Ca and Ca ++ was minimally increased at a normal level of PTH, no other disorders of calcium metabolism were observed during the screening. Interestingly, the first clinical manifestation of HPT in all patients was damage of the musculoskeletal system - mainly arthralgia, as well as arthritis of large and small joints. Moreover, all patients had a different CPPD phenotype: patient A - asymptomatic chondrocalcinosis, patient B - chronic arthritis (pseudo-rheumatoid form) and patient C - chronic arthritis (pseudosteoarthritis). Conclusion: The deposition of calcium pyrophosphate crystals may be an early predictor of the development of PHPT and precedes other manifestations. Disclosure of Interests: Aleksandra Novikova: None declared, Maxim Elisеev Speakers bureau: Berlin Chemie Menarini Group, Novartis International AG, EGIS, Olga Sheliabina: None declared, Maria Chikina: None declared