Intravenous Sodium Thiosulfate for Calciphylaxis

What calciphylaxis is

Calciphylaxis is a rare and serious disease in which calcium builds up inside the walls of the small blood vessels of the skin and the fat layer beneath it. Those vessels narrow, clot off, and stop delivering blood. The starved tissue dies, producing skin lesions that are intensely painful and extremely slow to heal.

The earliest and most consistent warning sign is pain that is far worse than the skin looks. Early lesions often appear as purple, blotchy, net-like discoloration. Over days to weeks these can harden into tender lumps or plaques, break down into deep ulcers, and develop a thick black crust of dead tissue called eschar. Lesions favor fatty areas such as the abdomen, buttocks, and thighs, but can occur below the knees and elsewhere.

Because early calciphylaxis resembles more common problems — venous ulcers, cellulitis, pyoderma gangrenosum, vascular disease — diagnosis is frequently delayed. Diagnosis is often made from the clinical picture together with risk factors; a skin biopsy can confirm it but carries a real risk of creating a new non-healing wound at the biopsy site, so the decision to biopsy is weighed carefully.

Two forms of the same disease

Most calciphylaxis occurs in people with kidney failure on dialysis, where disordered calcium, phosphate, and parathyroid hormone metabolism drives calcium deposition into vessel walls. This is the uremic form, sometimes called calcific uremic arteriolopathy.

The disease also occurs in people whose kidneys work normally or nearly so, which is called non-uremic calciphylaxis. It looks identical under the microscope but arises from different triggers: primary hyperparathyroidism, obesity, autoimmune and connective tissue disease, liver disease, cancer, corticosteroids, and above all warfarin.

Warfarin blocks activation of Matrix Gla Protein, one of the body's main natural inhibitors of arterial calcification, while also reducing the anticoagulant proteins C and S. The timing is a useful diagnostic clue. Warfarin-induced skin necrosis, a different condition, strikes within the first one to ten days of starting the drug. Warfarin-associated calciphylaxis appears much later — in a published series of 18 patients, an average of about 32 months into therapy, with a range from 1 month to 14 years.

How sodium thiosulfate is thought to work

Sodium thiosulfate has been used for decades as an antidote for cyanide poisoning, and more recently to protect children's hearing during cisplatin chemotherapy. Its use in calciphylaxis relies on entirely different properties. Three mechanisms are proposed, and it is worth noting that the mechanism in humans is still not settled:

• Calcium chelation. Thiosulfate binds calcium to form calcium thiosulfate, a far more soluble salt than the calcium phosphate deposits found in affected vessels. In principle this allows deposits to dissolve and the calcium to be cleared.
• Antioxidant effect. Sodium thiosulfate is a reducing agent that raises glutathione and scavenges reactive oxygen species, which may limit the endothelial injury and inflammation that drive the disease.
• Vasodilation. Thiosulfate generates hydrogen sulfide and improves nitric oxide availability, widening vessels and improving blood flow. This is the likeliest explanation for why pain often improves well before wounds visibly heal.

What the evidence actually shows

We think patients and referring physicians deserve a straight account of this, because the published picture is genuinely mixed.

What treatment looks like here

Your prescribing physician sets the regimen. The table below reflects the approaches most often described in the literature.

Situation	Typical regimen	Notes
On hemodialysis	25 g, three times weekly	Usually given at the dialysis unit during the last 30–60 minutes of a session, so clearance is aligned. We can cover non-dialysis days when ordered.
Normal kidney function (non-uremic)	25 g, three times weekly	Given here as a standalone outpatient infusion.
Kidney impairment, not on dialysis	Reduced dose, three times weekly	Dose is titrated to kidney function, since the drug is cleared renally and can accumulate.

A typical visit

1. Before you start. We verify benefits and pursue prior authorization, review your medication list, and confirm baseline labs with your physician — bicarbonate, anion gap, sodium, calcium, and kidney function.
2. Pre-medication. Nausea is the most common reason patients stop this therapy, so an anti-nausea medication such as ondansetron is given routinely beforehand rather than in response to symptoms.
3. Access. We use your port, PICC, or tunneled line when you have one. With a peripheral IV we dilute further, choose a larger proximal vein, and monitor the site continuously.
4. The infusion. The dose is diluted and infused slowly over 30 to 60 minutes on a programmed pump. Blood pressure is checked before, during, and after, because infusing too quickly can drop it sharply.
5. After. You are observed until stable. We send treatment notes and lab results to your referring physician and wound care team so the whole plan stays coordinated.

Side effects and how they are managed

Sodium thiosulfate is demanding to tolerate, and honest expectations help. The main issues are predictable and manageable with monitoring:

• Nausea and vomiting affect roughly one in five patients and are the most common reason for discontinuation. Routine pre-medication substantially reduces this.
• High anion gap metabolic acidosis. The drug is metabolized to acidic byproducts that can lower blood bicarbonate. Bicarbonate and anion gap are followed, and oral sodium bicarbonate, a dose reduction, or a pause may be needed.
• Sodium and fluid overload. A 25 gram dose carries roughly 316 milliequivalents of sodium, about 7.3 grams of elemental sodium. In patients who cannot excrete it this can cause swelling, elevated blood pressure, high serum sodium, and in severe cases fluid in the lungs. Electrolytes and weight are tracked, and fluid restriction or diuretics may be required.
• Low blood pressure if infused too rapidly. This is why the infusion is deliberately slow and never given as a push.
• Vein irritation with peripheral administration, because the solution is hyperosmolar. Careful site selection, dilution, and continuous observation minimize this.

One part of a larger plan

No single drug controls calciphylaxis. Infusion therapy works only alongside the rest of your care, and we function as one node in that network rather than as the whole treatment:

• Nephrology manages mineral and bone disease — stopping calcium-based phosphate binders and active vitamin D where appropriate, lowering dialysate calcium, intensifying dialysis, and using non-calcium binders or calcimimetics such as cinacalcet, with parathyroidectomy in selected cases.
• Wound care and surgery control infection and remove dead tissue. Debridement was historically avoided for fear of worsening lesions, but a Mayo Clinic series found markedly better one-year survival in patients who underwent surgical debridement (61.6%) compared with those who did not (27.4%), and later work has supported careful, well-selected operative management.
• Dermatology is often the specialty that recognizes the disease first and guides the biopsy decision.
• Pain management and palliative care matter enormously. Calciphylaxis pain is severe and frequently resistant to standard analgesia, and it deserves dedicated attention.

Information for referring providers

We accept referrals from nephrology, dermatology, wound care, and primary care across Northeast Ohio. What we provide:

• Administration of physician-ordered sodium thiosulfate with pump-controlled infusion rates and continuous nursing observation.
• Both central and peripheral administration, with documented protocols for peripheral use given the hyperosmolarity of the drug.
• Routine 5-HT3 antagonist pre-medication and monitoring of vital signs, electrolytes, bicarbonate, anion gap, and volume status.
• Benefits verification and prior authorization support for off-label use, completed before the first dose.
• Treatment notes and laboratory results returned to your office throughout the course.
• Scheduling flexibility around dialysis days, wound care visits, and hyperbaric oxygen sessions.

To send an order or arrange a peer-to-peer discussion, call (216) 755-4044 or fax 330-967-0571.

Common questions

Getting started

If you or someone you care for has been diagnosed with calciphylaxis, timing matters. Call (216) 755-4044 or send us a message and we will walk through orders, insurance, and scheduling.

CarePoint Infusion Center
23215 Commerce Park, Suite 318, Beachwood, OH 44122
Phone (216) 755-4044 · Fax 330-967-0571 · [email protected]
Monday–Thursday 8:00 AM–5:00 PM, Friday 8:00 AM–12:00 PM

Related pages

• All infusion services at CarePoint
• Iron infusion therapy
• IVIG therapy
• How prior authorization works
• What is infusion therapy?