Calciphylaxis (calcific uremic arteriolopathy) !

Calciphylaxis is a rare, very painful disease, mostly in people on dialysis, in which calcified small skin vessels clot and the skin and fat die.

Updated 2026-11-01

Structures involved

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Why it happens

What it is

A rare and often fatal disorder in which calcium deposits in the wall of small arteries and arterioles of the skin and subcutaneous fat, followed by clotting, leads to ischaemic, painful necrosis of skin and fat. It is seen mainly in people with kidney failure on dialysis.

Who gets it

Uncommon, but among the most feared skin complications of end-stage kidney disease; it affects a small fraction of people on dialysis each year, more often women and people with obesity or diabetes. As dialysis access grows in Colombia and Latin America, nephrology and dermatology services see it more often. Rare non-uraemic cases occur with normal kidney function.

Causes

End-stage kidney disease on haemodialysis or peritoneal dialysis (calcific uraemic arteriolopathy)
Disturbed mineral metabolism: high phosphate, high calcium-phosphate product and secondary or tertiary hyperparathyroidism
Non-uraemic forms with primary hyperparathyroidism, alcoholic liver disease, cancer or connective-tissue disease
Vitamin K antagonist (warfarin) use, which lowers active matrix Gla protein, an inhibitor of vascular calcification

Risk factors

Dialysis, especially for longer periods
Female sex, obesity and diabetes
Warfarin therapy
Calcium-based phosphate binders and active vitamin D analogues
Low serum albumin and recent rapid weight loss
Glucocorticoids or other immunosuppressants
Hypercoagulable states such as protein C or S deficiency

Pathophysiology

Small arterioles of the dermis and subcutaneous fat develop medial calcification and intimal fibrosis, narrowing the lumen. Endothelial injury then triggers thrombosis, and the tissue they supply becomes ischaemic and dies. Kidney failure promotes this through phosphate retention, hyperparathyroidism and loss of natural calcification inhibitors such as fetuin-A and matrix Gla protein.

Classification

Uraemic (calcific uraemic arteriolopathy), in chronic kidney disease, mostly on dialysis
Non-uraemic, with normal or near-normal kidney function
By site: central (trunk, abdomen, buttocks, thighs, over fatty areas) or distal (legs, fingers, penis)

Symptoms and signs

Severe, burning pain that is often out of proportion to what is seen, and may come before visible lesions
Violaceous, net-like (retiform) purpura and painful firm plaques or nodules in the skin
Blood-filled blisters that break into deep, black necrotic ulcers (eschar)
Lesions mostly on the thighs, abdomen, buttocks and legs, over areas rich in fat
Slow or absent healing of the ulcers

Diagnosis

Clinical: Suspected in a person on dialysis (or with other risk factors) with very painful retiform purpura, plaques or necrotic ulcers on fatty areas. The diagnosis is often clinical when the picture is typical.
Tests: Calcium, phosphate, parathyroid hormone, alkaline phosphatase, albumin and coagulation studies; screening for hypercoagulable states where relevant. A deep incisional (wedge) skin biopsy that includes subcutaneous fat shows calcified, narrowed small vessels with thrombi and fat necrosis, but it can provoke new ulcers, so it is used with caution. Wound cultures if infection is suspected.
Imaging: Plain radiographs or mammography-type soft-tissue films may show fine net-like calcification of small vessels; bone scintigraphy can show uptake in affected soft tissue. Neither is specific.

Differential diagnosis

Warfarin-induced skin necrosis
Cellulitis or necrotising fasciitis
Cutaneous vasculitis and cryoglobulinaemia
Antiphospholipid syndrome and other thrombotic vasculopathies
Pyoderma gangrenosum
Cholesterol (atheroembolic) emboli to the skin
Peripheral arterial ulcers

Goal of treatment

Control pain, prevent and treat wound infection, stop the process that calcifies small vessels (correcting calcium, phosphate and parathyroid hormone and removing triggers such as warfarin) and allow the wounds to heal.

Treatment

Acute: Multidisciplinary care (nephrology, dermatology, wound care, surgery, pain and palliative care); strong analgesia; prompt antibiotics when there is wound infection or sepsis.
Medical: Correction of mineral disorders: more intensive dialysis, non-calcium phosphate binders, stopping calcium supplements and active vitamin D, and calcimimetics when parathyroid hormone is high. Warfarin is usually replaced by another anticoagulant.
Medical: Sodium thiosulfate is the most widely used specific therapy, although evidence comes mainly from case series; bisphosphonates and hyperbaric oxygen have also been reported.
Surgical: Surgical debridement of necrotic tissue in selected cases, and parathyroidectomy when hyperparathyroidism is severe and does not respond to drugs.
Follow-up: Nursing care: careful wound care and dressings, regular pain scores, watching for signs of infection, pressure-area care and nutritional support to raise albumin.

Complications

Wound infection and sepsis
Chronic non-healing ulcers and loss of limb (amputation)
Severe chronic pain and loss of mobility
Malnutrition and debility
Death, mainly from infection

Prognosis

Poor: mortality in dialysis-related cases is high, often reported above half of patients within a year, mostly from infected wounds and sepsis. Central (trunk) lesions do worse than distal ones; warfarin-related cases and early, combined treatment have better outcomes.

Prevention

Good control of phosphate, calcium and parathyroid hormone in chronic kidney disease
Avoiding excess calcium load and, where possible, warfarin in people on dialysis
Early assessment of any new painful skin lesion in a dialysis patient

Test yourself

Think of the answer, then tap the question to see it.

Which patient group is classically affected by calciphylaxis?

People with end-stage kidney disease on dialysis, especially women, people with obesity or diabetes, and those taking warfarin.

What is the typical skin finding in calciphylaxis?

Extremely painful violaceous retiform purpura and firm plaques that turn into black necrotic ulcers, mainly over fatty areas such as thighs and abdomen.

What does a deep skin biopsy show in calciphylaxis?

Calcification of the media of small arterioles in the subcutaneous fat, with intimal narrowing, thrombi and fat necrosis.

Which anticoagulant is a known risk factor for calciphylaxis and why?

Warfarin (vitamin K antagonists), because it reduces activation of matrix Gla protein, a natural inhibitor of vascular calcification.

What is the main cause of death in calciphylaxis?

Infection of the necrotic wounds leading to sepsis.

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Educational information, not medical advice. For any symptom, see a health professional.

Sources: Calciphylaxis: Causes, Symptoms, and Management (DermNet, 2024).

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Representative model, for educational purposes only.

Skin highlighted on the Durgical 3D model