Causes of secondary gout

As discussed briefly above, high uric acid levels can be classified as arising from overproduction of uric acid, or preventing its excretion in the kidneys. Some, such as alcohol, operate through both mechanisms.

Factors that may cause an overproduction of uric acid:

• Certain cancers and their treatment

• Psoriasis

• Hemolytic anaemia

• Alcohol

• Fructose (in many soft drinks)

• Rarely: warfarin, vitamin B12

Factors that may cause an under excretion of uric acid

• A large number of drugs:

• Low dose aspirin

• Cyclosporin

• Diuretics

• Alcohol

• Kidney disease

Saturnine gout

An interesting example of gout caused at least partly by under excretion of uric acid is ‘saturnine gout’. This is now of largely historical interest but when lead poisoning was a common problem (lead in water from lead piping, children ingesting lead paint, or in ancient Rome, the use of lead salts to sweeten wine) the lead prevented excretion of uric acid and caused gout. Gout was a common problem in Ancient Rome.

How can my doctor and I be certain my pain is gout?

When a patient describes what has happened to a doctor he/she will try and elicit a history of the symptoms. This information will include:

• the site of the pain

• its severity

• if there was swelling

• how long it lasted

• if it has happened before

• if there is a family history

• any alcohol consumption

• medication the patient may be taking etc.

The doctor will then perform an examination, and if suspecting gout this will generally involve examining the affected area. It may also cover anything else relevant arising from the history given, and an examination for tophi, the soft tissue deposits of uric acid.
If the patient has given a typical history, of very severe pain and swelling, lasting 7-10 days, affecting a big toe, there is usually little room for doubt about the diagnosis, as few very other conditions behave in this manner. If there are atypical features such as an unusual joint being affected, or longer attacks than expected, other possibilities may need to be considered.

What tests might the doctor order?

It follows from the above that there is often no need for specific tests to make a diagnosis of gout. Nevertheless, both patients and doctors may feel more comfortable if some tests are performed to confirm the diagnosis, particularly if there are some unusual features.

Aspiration of the affected joint

This refers to taking a sample of fluid from the affected joint with needle and syringe. Sometimes this must be done, for example, if there is concern that the joint is inflamed because of an infection, rather than gout. However, it can be a painful procedure, may be difficult to perform, and will rarely be done outside a hospital setting.

Blood tests

We have discussed how most patients who suffer gout will have high uric acid levels in the blood. However, it is usually unhelpful to perform blood tests at the time of an attack. This is because, as a result of the intense inflammation, uric acid is excreted more effectively in the urine during an acute attack, and the levels of uric acid level in the blood actually fall, and so can be misleadingly normal.
It is more helpful to measure the uric acid level in the blood about 6 weeks later. This will be more representative, and the doctor will usually take the opportunity to check for impairment of kidney function, high cholesterol and diabetes, all of which are more common in gout sufferers. It is important to realize however that uric acid levels can vary quite widely on a day-to-day basis and treatment should not be based on a single measurement.

X-rays and scans

These are rarely helpful. Unless there have been recurrent attacks of gout for many years, X-rays will not reveal any abnormality. Uric acid deposits are not visible on X-ray or in any type of scan, and it takes many years for any damage to occur which might be visible on an X-ray.
If X-rays of a big toe are performed they almost inevitably show some osteoarthritis (‘wear and tear’) affecting the big toe joint, as this is as common as wrinkles on the forehead. This may in part explain why gout occurs commonly in the big toe, as it seems to have a predilection for worn joints, but such wear and tear is by no means necessary for it to occur.