Calciphylaxis: symptoms, causes and treatment

The National Kidney Federation and Kidney Care UK both say there is currently no specific treatment shown to work. Instead, doctors individualise care to reduce risk factors. The Oxford Kidney Unit leaflet explains that treatment involves controlling any calcium, phosphate and parathyroid hormone (PTH) imbalances and is coordinated by a team that includes a dietitian, pharmacist, bone and mineral metabolism nurse, pain management team, dermatologist, tissue viability (wound care) specialist and kidney specialist.

The Oxford leaflet lists measures that may be used. Which ones apply depends on your dialysis, medicines and other conditions, and your kidney team will decide.

• Limit high-phosphate foods in your diet, with advice from a dietitian.

• Adjust haemodialysis for more frequent or longer sessions, or switch temporarily from peritoneal dialysis to haemodialysis.

• Use a dialysis fluid with a lower calcium concentration.

• Take phosphate binders with meals and snacks.

• Review medicines, including stopping calcium-containing medicines and reviewing blood-thinning treatment, especially warfarin.

• Cinacalcet or etelcalcetide may be prescribed to optimise parathyroid hormone control.

• Sodium thiosulfate by injection, usually given during haemodialysis, is used off-label for calciphylaxis.

• Regular pain relief, wound care from tissue viability and dermatology teams, and rotating insulin injection sites to lower infection risk.

Kidney Care UK says calciphylaxis causes rashes and skin ulcers, usually on the legs and abdomen but possibly anywhere. The ulcers can be extremely painful and can become infected. The Oxford leaflet says it tends to happen on the thighs, abdomen, buttocks, lower legs, breasts or penis.

The National Kidney Federation notes that the pain can seem disproportionate, worse than you would expect for the size of the ulcer. If ulcers become infected, hospital admission may be needed, and people can feel weak and unwell.

• Skin discolouration or mottled skin.

• Hard black scabs, wounds or ulcers that do not heal.

• Hard lumps under the skin.

• Itching or tenderness of the skin.

• Severe pain in the affected area.

The exact cause is unknown. Kidney Care UK describes calcium and phosphate building up in the body and causing chalky deposits in the small blood vessels supplying the skin and muscles, reducing blood flow. The National Kidney Federation says the lack of blood supply stops enough oxygen reaching the skin, producing painful ulcers.

Risk factors that appear to make it more likely are listed in the table. The National Kidney Federation adds that the trigger may include local injury, with some people reporting that it began with a flea bite, cut or graze.

Kidney Care UK says it affects around 1 in 10,000 people in the UK and occurs in 1 in 600 people receiving dialysis. It can also occur in people with chronic kidney disease who are not on dialysis, after a kidney transplant, or very rarely in people without kidney disease. The National Kidney Federation similarly says it can sometimes occur in people who do not have kidney disease.

It is usually diagnosed in later adulthood and is more common in women than in men, although the reason is unknown.

There is no diagnostic test. The National Kidney Federation says diagnosis is made by clinical examination. Oxford Kidney Unit says it is usually recognised on physical examination, and blood tests may show an imbalance in calcium, phosphate and PTH and a raised C-reactive protein (CRP), which is also high in infection or inflammation.

A skin biopsy can be taken to look for calcification, usually by a dermatologist, but it is not always needed. Both Kidney Care UK and Oxford say biopsies can affect healing, so they are used selectively, such as for unusual-looking ulcers.

Oxford Kidney Unit says calciphylaxis is a serious condition and that, despite treatment, you may develop further skin lesions that can cause your health to deteriorate. Managing it may take many months. The National Kidney Federation says that whilst some people make a good recovery, around 5 out of 10 people die within a year of diagnosis.

These figures come from a small number of people because the condition is so rare, which has limited large research studies. The UK Calciphylaxis Study, led from Salford, aims to understand how it develops, what risk factors matter and which treatments give better outcomes.

Oxford Kidney Unit suggests several things. Do not miss haemodialysis sessions, because sometimes extra dialysis is suggested. Control your phosphate level by reducing high-phosphate foods, with advice from a renal dietitian, and take all prescribed medicines. Try to avoid injury to the skin, cover wounds or ulcers (which may need specialist tissue viability care), and tell your kidney team about any pain, since pain relief in kidney disease needs extra care and often takes several different medicines to get right.

Kidney Care UK adds keeping any cuts clean to prevent infection, good nutrition to promote healing, and psychological support. Dietary changes include limiting high-phosphate foods such as cheese and nuts. If you or your family are finding it hard to cope, the Oxford leaflet says you can ask the kidney team about renal supportive care.

Painful skin ulcers or black scabs in someone with kidney disease or on dialysis should be reported to the kidney team promptly. Kidney Care UK says that if ulcers become infected, hospital treatment may be needed, and the National Kidney Federation says infected ulcers can lead to hospital admission.

Contact your kidney team or NHS 111 promptly if an ulcer looks infected, or if you develop a fever or feel very unwell. Renal wards and dialysis units give their patients contact numbers for advice, and the Oxford leaflet lists a 24-hour number for its renal ward.

Calciphylaxis is managed by NHS renal (kidney) teams. The National Kidney Federation says there is no specialist hospital that treats calciphylaxis, because there is no specific treatment, but kidney teams can seek advice from clinicians with an interest in the condition through a UK calciphylaxis rare disease group.

Because care combines dialysis planning, medicines, wound care and pain control, it is usually best delivered through the team already looking after your kidneys.