About Gout

Gout is a disease triggered by abnormal uric acid metabolism. When uric acid levels in the body are too high, urate crystals are formed and deposited in the joints and surrounding tissues, which triggers an inflammatory response and leads to severe pain in the patient. In order to effectively prevent and control gout, we need to address the problem of abnormal uric acid metabolism at its source.

Uric acid production and metabolism

Uric acid production is closely related to a number of factors, including dietary intake, genetic factors, metabolic abnormalities, and kidney function. Uric acid, as the end product of human purine metabolism, is produced mainly through the breakdown of ingested nutrients and endogenous synthesis. Purines are converted to uric acid by metabolism in the liver. Although uric acid can be further converted to the highly soluble allantoin by the enzyme uricase, excretion of uric acid is mainly dependent on the kidneys because the body lacks the enzyme.

Uric acid metabolism

In humans, the uricase gene is usually in a state of non-expression, thus the body lacks the enzyme uricase, resulting in the majority of purine metabolism stopping at the formation of uric acid.

The body has a limited ability to metabolise urate and therefore excretes it mainly through the kidneys (70% of the body) and the intestines (30% of the body). Specifically, after glomerular filtration, urate is reabsorbed in the renal proximal tubules, which in turn secrete uric acid for excretion through different mechanisms. Uric acid that enters the intestine, on the other hand, is mainly degraded by the intestinal flora.

Causes of gout/abnormal uric acid metabolism

1. Inborn factors
Such as enzyme defects, impaired purine metabolism, inactivation of the uricase gene, and genetic defects in key ion channels for uric acid transport or key enzymes in uric acid synthesis;

2. Dietary factors
such as excessive intake of high-purine foods;

3. Renal factors
e.g. decreased renal tubular secretion, decreased glomerular filtration or increased tubular reabsorption;

4. Medication factors
e.g. the use of drugs such as tachycardia, etanercept, pyrazinamide, aspirin, etc. may inhibit uric acid excretion;

5. Other factors
such as leukaemia, multiple myeloma, lymphoma and chemotherapy or radiotherapy for malignant tumours may lead to overproduction of uric acid.

In summary, gout is actually a disease caused by elevated uric acid due to a variety of factors.