Uric Acid in Joints: Crystals, Salt Deposits, and Pain

Uric acid is a breakdown product of purines that normally dissolves in the blood and is excreted by the kidneys. If too much is produced or excretion is impaired, blood levels rise, and in some people the acid forms needle-shaped crystals around the joints, causing pain. This article explains when this condition is called gout and how to recognize it.

What uric acid is and where it comes from

Uric acid is a breakdown product of purines, substances from body tissues and many foods. When the body processes old cells or purine-containing food, most of the acid dissolves in the blood, and the kidneys excrete it in urine. Sometimes the body produces too much of it or removes too little. Then blood levels rise — this is called hyperuricemia. On its own, it does not cause problems in everyone, but in some people the acid forms needle-shaped crystals.

How uric acid crystals are deposited in joints

Crystals form around and inside joints, and they are what causes pain. Over time, if gout is not treated, hard nodules — tophi — appear under the skin, usually on the ears, fingers, or elbows. At first they are painless; later they may hurt, damage bones and soft tissues, and change the shape of joints. Crystals can also cause kidney stones.

Symptoms: joint pain, the big toe, and other locations

Gout is an inflammatory arthritis that usually flares up in one joint. Most often it is the big toe, but other toes, the ankle, knee, as well as the hands, wrists, and elbows may be affected. An attack often begins at night: severe pain, sometimes waking the person, swelling, redness, and warmth of the skin over the joint. On dark skin, redness is harder to notice. Without treatment, an attack lasts one to two weeks, and subsequent attacks may be longer. Between attacks, there are usually no symptoms.

• sudden severe pain in one joint, often the big toe;
• swelling, redness, and warmth over the affected joint;
• attacks recur more often if gout is not treated;
• hard nodules under the skin in long-standing disease.

Causes of uric acid accumulation in joints

Gout sometimes runs in families and is more common in men, especially with age. Risk is higher with excess weight, alcohol consumption, after menopause, and with certain medications — diuretics, blood pressure drugs, low-dose aspirin. High cholesterol, hypertension, kidney disease, osteoarthritis, diabetes, and previous surgeries and injuries also play a role. An attack may be triggered by a febrile illness, heavy meals, dehydration, or joint injury.

Why joints hurt when blood uric acid is normal

Elevated blood uric acid does not always mean disease and does not cause problems in everyone. A similar picture is produced by pseudogout — deposition of calcium crystals rather than uric acid. To sort this out, the doctor assesses the complaints and examines the joint, and if necessary tests joint fluid under a microscope and orders ultrasound or CT.

Diagnosis, complications, and when to see a doctor

The doctor asks about symptoms, diet, and alcohol, examines the joint, and may order a blood or urine test for uric acid. If the picture is unclear, the patient is referred to a rheumatologist: a sample of joint fluid is taken with a thin needle and examined for crystals under a microscope, and ultrasound or a special CT is performed. Without treatment, joint damage, tophi, kidney stones, and chronic arthritis are possible. See a doctor at the first attack and when usual treatment does not help.

Gout itself is not a reason to call an ambulance. With sudden joint pain and swelling accompanied by worsening pain, very high fever, chills, or nausea — seek medical help urgently (joint infection is possible); 103/112 — for a life-threatening condition.

Write down questions for the doctor: what tests do I need, what do my numbers mean, could the medication I take have had an effect. This material is for reference and does not replace a doctor's consultation — the final decision is always theirs.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer