Calcium oxalate crystals are hard and strong, like bone, arranged in a repeating pattern. The crystals' sharp edges are abrasive grinding surfaces, which may injure body tissue and cause joint damage and pain. A large calcium crystal deposit can produce a bulging tendon in the arm, for example, which causes discomfort and pain in the upper arm and shoulder. The inflamed tendon between the bones in the shoulder makes it difficult to raise the arm laterally or outward.
Calcium Crystals in Arthritis
Calcium crystals may be calcium phosphate or calcium oxalate. Calcium crystals embedded in joints usually do not interfere with the working of the joint. The calcium crystals usually become dislodged and disappear.
The rough grinding surfaces of the calcium phosphate or oxalate crystals may inflame tendons in a condition known as calcifictendinitis, or the crystals may cause hot painful swollen "pseudogout." In pseudogout, calcium crystals form in joints. With gout uric acid crystals form in joints.
Calcifictendinitis usually occurs in the shoulder. Chondrocalcinosis, or calcium crystals in cartilage, tears at the hyaline cartilage at the end of a bone. Calcium phosphate crystals usually cause chondrocalcinosis. Calcium chondrocalcinosis from calcium oxalate is rare and occurs only in dialysis patients.
Chronic calcium crystal arthritis may be more troublesome, painful and severe than most osteoarthritis, but usually there is no difference between osteoarthritis with crystals and osteoarthritis without crystals.
A specific concentration of calcium oxalate in solution is one condition required for calcium oxalate crystal formation. Inhibitor proteins usually prevent the crystals from developing in blood, urine or soft tissue. Promoters facilitate calcium crystal formation.
Crystals form when the serum, urine or soft tissue balance between inhibitors and promoters is conducive to crystal formation. Osteoarthritis and ageing alter the inhibitor-promoter balance. An acute attack of inflammation and pain starts in the arm and shoulder within 12 to 36 hours after crystals embed in tissue surrounding the shoulder joint. Pain in the upper arm and shoulder worsen, and you have difficulty raising your arm outward.
Inhibition of Crystal Formation
Kidney stones are one of the most common urinary tract problems. Kidney stones are hard masses of calcium oxalate, calcium phosphate or uric acid crystals. Normal urine is frequently supersaturated with calcium oxalate, but most humans do not form stones.
Uropontin, a protein similar to pontin proteins found in bone, plasma and breast milk, occurs in urine. Uropontin has an inhibitory effect on calcium oxalate crystal growth, which indicates that the pontins have a regulatory role in calcium crystal formation.
Kidney Failure and Arthritis
During chronic renal failure, calcium oxalate crystals are deposited in synovial fluid and cartilage. Under the microscope, the calcium oxalate crystals look like calcium phosphate crystals associated with knee osteoarthritis. Joint disease in chronic renal failure may be the result of calcium oxalate deposits.
No dietary change is necessary to prevent calcium oxalate crystal formation. Drinking at least 2 quarts of water per day definitely helps. Special diets and supplements are needed only for metabolic disorders, such as a magnesium deficiency or a kidney problem.
Hypercalciuria is inherited. Calcium-based antacids may increase calcium oxalate crystals, as does chronic inflammation of the bowel or intestinal bypass surgery. Your doctor may recommend limiting high oxalate food. Rhubarb, spinach, beets, wheat germ, soybean crackers, peanuts, chocolate, black Indian tea, and sweet potatoes are high oxalate foods. Grits, grapes, celery, green peppers, raspberries and liver are moderately high in oxalates.