Calcium Pyrophosphate Dihydrate (CPPD) Crystal Deposition Disease, or Pseudogout
False gout (pseudogout) causes gout-like attacks of acute local joint pain and swelling in patients with chondrocalcinosis. That tongue twisting term means calcium pyrophosphate crystal deposits in cartilage, which are usually visible on x-rays of a pseudogout patient’s joints. The calcium deposits cause pseudogout.
Like gout, pseudogout can significantly interfere with normal life. At the worst end of the spectrum, acute attacks can incapacitate a person for days or even weeks. The calcium crystal deposits can also encourage severe joint degeneration, leading to chronic disability.
Feels Like Gout, But It Isn’t
Is CPPD Crystal Deposition the Same Thing as Pseudogout?
CPPD crystal deposition happens about equally in men and women. If either of your parents have it, you have about a 50% probability of developing it as you grow older. Getting lots of calcium in your food does not cause crystal deposition–something goes wrong to make the deposits happen.
Some people with CPPD crystal deposits in their joints have no symptoms, so the crystal deposits do not always cause trouble.
Among people with CPPD crystal deposits in their joints, about half develop a disease very much like osteoarthritis. About a quarter develop the type of acute arthritis commonly called false gout or pseudogout. Some of the remaining people develop a chronic inflammatory condition very much like rheumatoid arthritis.
Does Pseudogout Happen Alone, or With Something Else?
The reason behind formation of the crystal deposits is usually unclear. Both gout and pseudogout are most common above age 60, so they tend to be regarded as associated with aging. However, in some cases a family pattern of pseudogout diagnoses suggests a genetic cause.
Pseudogout can be associated with any of several problems. Upon discovery of pseudogout, the patient should also be checked for:
- hemophilia, in which the patient’s blood does not clot normally
- ochronosis, a bluish black discoloration of cartilage caused by exposure to certain noxious agents such as benzene, or more often as a result of the rare recessive metabolic disorder alkaptonuria which causes unprocessed homogentisic acid (HGA) to build up in cartilage (leading to chronic inflammation, degeneration, and osteoarthritis)
- amyloidosis, a group of diseases due to abnormal deposition of a protein called amyloid, in various tissues of the body
- hypothyroidism, an underactive thyroid gland, causing symptoms that include fatigue, weight gain, and a tendency to feel cold, which can progress to myxedema
- myxedema, a disease caused by an underactive thyroid gland, leading to symptoms that include dry skin, swelling around the lips and nose, mental deterioration, a subnormal basal metabolic rate, and coma in extreme cases
- hemochromatosis, commonly called iron overload disease, a relatively common hereditary disease in which too much iron builds up in the body
- hyperparathyroidism, overactive parathyroid, click here to go to a lens about this
How Do Gout and False Gout Differ?
Both gout and pseudogout are caused by deposits of crystals in joints. Your joints are meant to have smooth cartilage and no bits of anything hard floating in the fluid that lubricates them. Take two smooth pieces of plastic, drizzle a little oil between them, and rub them together. That’s how your joints are meant to work. Sprinkle sand or salt between them and rub them together again to get some sense of what the crystal deposits in joints are doing.
In gout the offending substance is monosodium urate. When joint fluid is examined under a microscope, the crystals involved are visibly different, but the effect is similar.
It is possible to have both gout and pseudogout at the same time. In one study, 5.5% of gout patients also had the crystals that cause pseudogout. In that study, X-ray images for patients who had both diseases showed visibly calcified joint fluid.
In pseudogout, acute episodes are believed to occur when some of crystals that have been deposited in cartilage get loose in the joint fluid instead. These attacks can happen for no apparent reason, or they can be triggered by serious illness, trauma or surgery.
Gout has a predeliction for affecting the big toe. By contrast, about half of all pseudogout attacks affect the knee, although pseudogout can affect any joint. Bad attacks can be accompanied by a fever.
What Can Be Done About It?
The most appropriate type of doctor to help with pseudogout is typically a rheumatologist, although a severe case may wind up being treated by an orthopedic specialist. Treatment starts out like this:
Patients can also use cold packs on a joint that is suffering an attack. Dehydration can bring on an attack, so it is a good idea to drink adequate fluid every day. That is especially true after any type of surgery, since an attack often follows surgery.
Most of the books available at Amazon about this are expensive, highly technical medical texts. I’ve chosen one written for ordinary people and a medical primer (not a heavy-duty specialist’s reference book).
Most information for this lens came from the sources below, with some additional tidbits from Medscape / Medline, and the US National Institutes of Health. If you are searching for more information about false gout, try CPPD as one of your search terms. That will find some information that is relevant but does not appear for any of the other keywords you may be using.
Gout and false gout fall within the purview of rheumatologists.
This organization makes a point of providing understandable information for patients. Excellent, thorough material but you don’t need a medical degree to make sense of it.
I am not a medical professional. Years ago I was a volunteer sysop in an online forum for people with chronic illnesses. The forum was so highly regarded that some doctors sent patients to it to learn how to live with their illnesses. I did a fair amount of translating from medical jargon into something more understandable for the benefit of the forum’s members.
If you need a detailed understanding of this topic, please talk with your doctor and consult formal medical literature. I’m no substitute for that!
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