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Calciphylaxis

Calciphylaxis is a serious condition that can occur in people chronic with kidney disease; it is most commonly seen in people receiving dialysis but remains very rare with approximately one case diagnosed in every 600 people, having dialysis, per year. It can sometimes occur in people that do not have kidney disease. It happens when small blood vessels in and around the skin become blocked by a build-up of calcium products; this is referred to as calcification. The blockage (calcification) leads to a lack of blood supply, preventing adequate oxygen from getting to the skin. This causes the development of painful skin ulcers which can lead to serious infections. 

What causes calciphylaxis?

The exact cause of calciphylaxis remains unknown; we do not know why some people get the condition and others do not. Possible risk factors (things that may contribute to the development of calciphylaxis) are considered to be:

  • Warfarin use (a blood thinning medication)
  • Long-term dialysis
  • High blood levels of calcium, and/or phosphate*
  • Being overweight

The trigger for the disease is not known but may include local injury; for example, people can report their calciphylaxis started with a flea bite, cut or graze to the area.

*If you have high levels of calcium/and or phosphate then please get in touch with your local kidney team for advice. If needed, your team should be able to refer you to a kidney dietitian who can provide you with tailored dietary guidance to help improve your blood phosphate levels. 

How is the condition diagnosed?

There is no diagnostic test for calciphylaxis. Diagnosis is made by clinical examination. Sometimes a skin biopsy can be taken (a small sample of skin is removed and tested) to check for evidence of calcification but this isn’t always necessary. 

How the illness affects people

Calciphylaxis commonly affects the soft tissues of the body around the abdomen and legs but can affect any area of the body including (but not limited to) the torso, breast and external genitalia. The main symptom (from the ulcers) is pain which can be extreme. If the ulcers become infected then this can result in hospital admission.  People can feel weak and unwell; this may be caused by a combination of factors including the pain, possibly infection, along with the burden of undergoing the treatments. Whilst some people make a good recovery, sadly around 5 out of 10 people die within a year of diagnosis. 

What can be done about it?

There is no specific treatment as yet that is shown to work. Your doctor will try and individualise your care to reduce your risk factors. This may include improving your calcium and phosphate levels or stopping medications such as warfarin. They may also consider experimental treatments or clinical trials where available. 

What’s new? Opportunities for research and development 

The rarity of the condition has limited the ability to do large research studies. 

  1. The UK Calciphylaxis Study is currently underway. This study aims to find out:
  • What the natural history and the development of the disease is (how calciphylaxis starts, the location of the ulcers, how well the ulcers heal and if the patient recovers)
  • What risk factors are associated with development and progression of calciphylaxis?
  • Which treatments offer a favourable outcome?

This study is being led by Professor Smeeta Sinha in Salford.

  1. An international study (BEAT-CALCI) is also underway aiming to determine the best treatment for the condition. The UK are hoping to become involved with this study. https://classic.clinicaltrials.gov/ct2/show/NCT05018221 
  1. Professor Sinha’s research team are currently developing a research study to investigate and understand patient experiences of calciphylaxis. The hope is this study will identify gaps and better understand patient needs to help health professionals to improve the care and support provided. 
  1. The Calciphyx study has recently finished recruitment. This study is investigating whether the investigational drug SNF472 can improve outcomes. The results should be available in 2023. https://clinicaltrials.gov/ct2/show/NCT04195906 

Patient support

At present there is not a patient support group for calciphylaxis; we are hopeful that contacts made through new research projects will change this in the near future. Information will be updated here when this happens. 

Further information

Calciphylaxis is a rare complication and the information available remains very limited. There is a need for greater awareness and support. If you have been diagnosed with the condition and would be willing to share your story or act a patient representative then please do get in touch with the Rare Renal Team https://ukkidney.org/rare-renal/contact-us/form.

Previous enquiries/questions to NKF 

1) What symptoms should I look for 

Calciphylaxis causes ulcers (skin sores). This commonly occur around the abdomen and legs but can affect any area of the body including (but not limited to) the torso, breast and external genitalia. The main symptom (from the ulcers) is pain which can be extreme and may seem disproportionate (worse than you would expect) for the ulcer size.

2) What treatments are available 

There is no specific treatment as yet that is shown to work. Your doctor will try and individualise your care to reduce your risk factors. This may include improving your calcium and phosphate levels or stopping medications such as warfarin. They may also consider experimental treatments or clinical trials where available. 

3) Is there a specialist hospital that can treat Calciphylaxis 

No. There are no specific treatments and therefore no specialist hospital that treats calciphylaxis. There are healthcare professionals in the UK that have an interest in calciphylaxis and your kidney team can contact them for advice (through the calciphylaxis rare disease group). 

4) Is there anything I can do as a patient/carer to help me control Calciphylaxis

Speak to your kidney team. Ask them about your blood results and if you need to make any changes. Make sure you let them know how you are feeling and how your symptoms are – they can then be guided by you. You will understand your symptoms, and needs, better than anyone and letting people know this will help them to manage your care.

Written by Professor Smeeta Sinha and Dr Sharon Huish (Lead and Co-lead of the UK Calciphylaxis Rare Disease Group).
July 2023
Next review July 2026

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The National Kidney Federation cannot accept responsibility for information provided. The above is for guidance only. Patients are advised to seek further information from their own doctor.