Background/Purpose:

Calcinosis, or dystrophic calcification, is a poorly understood, debilitating condition commonly manifested in connective tissue diseases such as scleroderma and polymyositis. Despite treatment of the rheumatologic disease, patients typically endure pain, infections, and decreased joint mobility. Therapeutic options for calcinosis, including coumadin, corticosteroids, diltiazem, probenecid, and colchicine, have shown little success, and treatment failure is common. Intravenous sodium thiosulfate (IV STS) is commonly used to treat calciphylaxis, and several mechanisms are proposed for its effects. Intriguingly, the chelating properties of IV STS form water soluble calcium-thiosulfate, which aids in dissolving deposited calcium salts. Additionally, STS increases production of glutathione and nitric oxide, which improve endothelial function, vasodilate blood vessels, and decrease tissue ischemia. Physiologically, it is feasible to hypothesize that IV STS may treat refractory calcinosis, but data is not available regarding its use. The following patient chart reviews illustrate this hypothesis:

Methods:

Patients #1, a 63 yo Caucasian female with limited scleroderma, and #2, a 46 yo Black female with polymyositis, suffer with recurrent calcinosis deposits of the skin and soft tissue causing pain and functional loss. Patient #1 reported severe pain and decreased mobility of her hands, and patient #2 reported deposits in her posterior thigh causing severe pain on sitting down and standing up. Aggressive therapy, including corticosteroids, colchicine, calcium channel blockers, and surgical interventions, yielded little improvement in pain and function. Each patient regularly reported pain scores of 8-9/10.  After discussing IV STS therapy and obtaining consents, infusions were started at 12.5 grams over one hour weekly and advanced as tolerated. The maximum doses achieved in patients #1 and #2 were 15 gm/week and 25 gm/week, respectively. Infusions were continued weekly for approximately seven months. The infusions were tolerated well, and the most common patient reported side effects were nausea and blurry vision. The most common laboratory abnormality was a non-gap metabolic acidosis.

Results:

As early as two weeks after starting the infusions, improvements in pain scores and softening of calcinosis deposits were observed. Both patients reported improved pain scores of 3-4/10 at two weeks and 0-1/10 at four weeks, and this persisted throughout therapy. At four weeks, functional status improved; specifically, patient #1 was able to grip a drinking glass without difficulty, and patient #2 was able to sit and stand with ease.

Conclusion:

The clinical improvements observed may be attributed to the inherent properties of IV STS. Intravenous STS therapy is approved for calciphylaxis as well as cyanide and chemo-related toxicities. Although calcinosis is pathologically different from calciphylaxis, the physiologic properties of IV STS may contribute to the clinical improvements outlined above. These findings illustrate the potential of IV STS to treat painful calcinosis and the need for further studies of its use in rheumatic disease.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/intravenous-sodium-thiosulfate-for-treatment-of-refractory-calcinosis-in-rheumatic-disease/