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What causes calcium crystal diseases?

Why do people get calcium crystal deposits?

Crystals are made up of very small geometric particles (atoms) arranged in a regular repeating pattern. This makes them very hard and difficult to break down. In certain substances this is helpful – for example, it contributes to the strength of bone and seashells. However, the hard sharp angles of calcium crystals can rub and grind down softer substances that come into contact with them. In addition, their rough surface has a strong electrical charge, which can injure cells and trigger an immune reaction (inflammation).

Even if you're perfectly healthy, the chemicals that form crystals may be present in your blood, urine or soft tissues. Other chemicals within the body either promote or inhibit the formation of crystals, and the balance between these chemicals tends to change as part of normal ageing. These changes are mainly localised to particular parts of the body and are the most likely reason for crystals forming.

Other possible causes of calcium crystal diseases are:

  • metabolic diseases – which affect the regulation of calcium or polyphosphate levels, including:
    • hyperparathyroidism (overactivity of the parathyroid glands)
    • haemochromatosis (also known as iron-storage disease)
    • hypomagnesaemia (magnesium deficiency)
  • genetic factors – recent research has found that an abnormality of the ANKH gene may lead to the production of too much pyrophosphate, which can result in widespread calcium crystal depositing. This can cause recurrent attacks of acute CPP crystal arthritis at an unusually young age (20s or 30s).

Uncommon causes of calcific tendinitis include diabetes, the kidneys not working properly or high calcium levels.

What triggers acute attacks?

Many attacks of acute CPP crystal arthritis and acute calcific tendinitis occur for no obvious reason, and it’s not clear why the crystals have been shed. But sometimes there’ll be something that has provoked the attack. For example, an injury to your knee or shoulder may shake the crystals loose, setting off an attack a day or two afterwards. Another common trigger is an illness that causes a fever, such as having flu or a chest infection. For some reason these illnesses encourage crystal shedding, leading to an acute attack. A major stress to your body – such as having an operation or a heart attack – may also trigger an attack.


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