CPPD & pseudogout

In CPPD, minute crystals of calcium pyrophosphate gather in a joint's cartilage and in its soft tissues. Crystals that break loose into the joint provoke a sudden, painful bout of inflammation, the attack often known as pseudogout. The same deposits are also linked with cartilage wearing away over the years, giving a more grumbling picture like osteoarthritis.

Usually there is no one cause to find, and the older people get, the commoner it becomes. Rarely it runs in a family. A joint injured in the past is likelier to develop it, and an earlier operation on the joint may be too; an injury, an operation or an illness with a fever can also set off an attack. Occasionally it comes with a condition of the body's chemistry, an overactive parathyroid gland, a low magnesium level or too much iron for example, and so a specialist may run a few blood tests when CPPD appears at a younger age than usual or its deposits are found in many joints.

CPPD does not always look the same. Its commoner features include:

• A joint, often the knee or the wrist, that turns hot, swollen and painful suddenly, often over a matter of hours
• Attacks much like gout's, though more often in a larger joint
• At times a more lasting, low-grade ache in the joints over the years

An attack occasionally brings a fever and a general feeling of being unwell. Rarely, the joint is infected (septic arthritis) rather than inflamed by crystals, and the two can be hard to tell apart; so if a fever or a growing sense of being ill comes with the attack, go the same day, either at A&E or by calling NHS 111 instead of waiting for a routine appointment. Shaking, confusion, rapid breathing, or feeling dramatically worse over hours make it a 999 or A&E emergency (the first list below). A joint worsening faster than in your usual attacks, even without a fever, needs seeing that day too, by one of the routes the second list gives.

To reach the diagnosis, a doctor weighs the pattern of symptoms and the examination, analyses fluid drawn from the joint if needed, and looks at imaging. Telling it apart from gout, and from everything else that makes a joint hot and swollen, is important, since each is managed differently in the long term.

Ultrasound is especially useful here: calcium crystals have a typical look on the scan that usually sets them apart from urate. Point-of-care ultrasound is part of the consultation with Dr Borukhson, so the scan is usually part of the same appointment; our ultrasound clinic page describes what it involves.

An attack is treated with an NSAID (an anti-inflammatory tablet) or with colchicine, or with a steroid, given as an injection into the joint, often straight after fluid is drawn off, or as tablets or an injection into a muscle when the others do not suit. Attacks usually settle on their own in time, and treatment eases the pain and swelling while they do. Where attacks keep coming back, the aim becomes making them less frequent. If one joint is badly inflamed, a steroid injection guided into it with ultrasound can help to settle it. You and Dr Borukhson settle the plan together.

Between attacks, keeping active can strengthen the muscles around the affected joints and ease symptoms, so keep the joints moving within comfortable limits rather than resting them completely; staying active has its own guide. Losing any extra weight can ease joint pain.

Have simple measures ready for the start of an attack, resting the joint and cooling it; colchicine works best when it is begun early in an attack. Food matters in gout, since some foods and drinks push urate up, but calcium in the diet does not cause CPPD, so there is no need to cut it down.

Attacks come and go, and most die down by themselves. Those that keep returning, or joints that stay sore, are worth having reviewed rather than endured, since treatment may make them less frequent.

An attack of pseudogout and an infected joint can look alike, which is why a hot joint in the lists below needs help fast. The two lists put the gravest signs first, and the less pressing ones follow them.

Treat any of these as a 999 or A&E emergency: call 999 and do not drive yourself to A&E.

• Severe illness with suspected sepsis: a high fever with shaking, confusion, rapid breathing, or feeling dramatically worse over hours
• With a fever or feeling unwell, a rash that does not fade when you press it, a stiff neck with eyes that cannot bear bright light, or skin, lips or tongue turning blue, grey, pale or blotchy, since these can be signs of meningitis or sepsis, as can a very bad headache, confusion or a first seizure with a fever or feeling unwell; on black or brown skin the rash and the change of colour may be easier to see on the palms of the hands or the soles of the feet
• A joint you cannot put weight on or move, or that has moved out of place, or, after a fall or injury, very bad pain or any tingling or numbness
• Chest pain that is crushing, tight or like a pressure, that spreads to an arm, the jaw, the neck, the stomach or the back, that comes with breathlessness, sweating, feeling sick or feeling light-headed, or that came on suddenly and does not go away
• Vomiting blood, or bleeding from the back passage that is heavy or will not stop, most of all with faintness, confusion or pain in the abdomen, or vomit that is black or dark brown, since anti-inflammatory tablets, often used to settle an attack, can make the stomach bleed
• Lips, mouth, throat or tongue that suddenly swell, a throat that feels tight, very fast breathing or a struggle to breathe or to swallow, skin, tongue or lips turning blue, grey or pale (on black or brown skin this may be easier to see on the palms of the hands or the soles of the feet), becoming suddenly very confused, drowsy or dizzy, or fainting and not being able to be woken, since this can be a severe allergic reaction, anaphylaxis, which can follow a dose of any medicine

Any of these needs an assessment that is urgent, on the same day, from your GP or NHS 111:

• A joint that is hot and swollen, with a fever or feeling unwell, since an infected joint has to be ruled out at once, at A&E or through NHS 111
• A joint whose swelling and pain build faster than in your usual attacks, an attack much more painful than is usual for you, or the first attack in a joint that has never been diagnosed, with no fever and even when you feel well in yourself, because an infected joint cannot yet be ruled out and can resemble pseudogout closely: an urgent GP appointment, NHS 111 or a specialist clinic that can see you that day
• Joint pain with a fever, or feeling hot, cold or shivery, or generally unwell, since an infection in or around a joint has to be found the same day
• While you take colchicine: diarrhoea, feeling or being sick, or pain in the stomach; a high temperature, bruising, or bleeding that goes on for a long time after an injury; muscle pain or weakness, or dark red or brown pee; or pain, tingling, loss of feeling or weakness, since these can mean that too much of the medicine has built up in the body or that it is affecting the bone marrow, the muscles and kidneys or the nerves; NHS 111 can tell you what to do that day, and a swollen throat or tongue, or difficulty breathing, is a 999 or A&E emergency: call 999 and do not drive yourself to A&E
• Black or dark red stools, on anti-inflammatory tablets, since a bleed in the stomach or gut has to be found that day

Short of the signs in the lists above, an attack like your usual ones can be managed as you have agreed with your team, and one that has not settled after two weeks is for your GP or rheumatology team to see within days; with a fever or feeling unwell alongside it, it belongs to the second list. Between attacks, see your GP or team for a routine review when hot, swollen joints keep coming back or a joint stays painful or stiff, so that the cause can be confirmed and a plan made. If you cannot tell how urgent something is, asking is never a mistake.

Since CPPD is so easily taken for gout, finding out which crystal is the cause is what puts the long-term approach on the right footing. Anyone who has had a joint turn hot and swollen in attacks can have the cause looked into by a specialist, with ultrasound where it helps.

What tests show that it is CPPD?

Your symptoms, an examination and which joints are affected are the starting point. The clearest answer comes from finding the crystal in a little fluid drawn off the joint, where that is needed. Scans add to this: calcium in the cartilage can show up on an X-ray, and ultrasound can pick up the same deposits. Point-of-care ultrasound is part of the consultation with Dr Borukhson, so the scan can often be done at your appointment.

What helps an attack of pseudogout, and how long does one last?

The aim is to calm the inflammation, usually with an NSAID (an anti-inflammatory tablet) or with colchicine, and with rest for the joint. A steroid injected into a single badly affected joint, often guided by ultrasound, can help it settle. Many attacks ease within several days to two weeks. If attacks keep returning, the plan turns to making them less frequent. Your situation shapes the approach, and nothing is done without your agreement.

What can I do for myself while an attack lasts?

Rest the joint and avoid overloading it, with gentle movement once the worst has passed. Ordinary painkillers can ease the pain, and some people find a wrapped ice pack on the joint soothing. These steps support medical treatment and do not replace it. Anything in the first list under When to seek help is a 999 or A&E emergency, and the second list gives the signs that need an answer the same day; an attack that has not settled after two weeks is for your GP or team to see within days, and attacks coming more often are worth raising with your GP or team at a routine review.

What sets CPPD apart from gout, and does the difference matter?

Each is a crystal arthritis that can make a joint suddenly painful and swollen, which is why one is so easily taken for the other. What differs is the crystal, calcium pyrophosphate for CPPD and urate for gout, and CPPD leans towards the bigger joints, the knee or the wrist for example. It matters because the two are managed differently over the long run: knowing which crystal is at work means the treatment you are offered fits your condition and not another.

Which signs need urgent care, and is a specialist worth seeing?

A joint you cannot put weight on or move, and anything else in the first list under When to seek help, is a 999 or A&E emergency. Call 999 and do not drive yourself to A&E. Infection and pseudogout can be hard to tell apart at first, so a hot, swollen joint together with a fever, shivers or a growing sense of being ill needs the same day, at A&E or through NHS 111. Also needing the same day, with no fever and even when you feel well in yourself, are a joint whose swelling and pain build faster than in your usual attacks, an attack much more painful than is usual for you, and a first attack in a joint not yet diagnosed, by an urgent GP appointment, NHS 111 or a specialist clinic that can see you that day. If hot, swollen joints keep returning without any of those signs, a routine visit to your GP or team, or to a specialist, with ultrasound if it would help, is worthwhile to confirm what is behind them and agree a plan.