Pseudogout is most common in the elderly. It involves deposits of calcium pyrophosphate dihydrate (CPPD) crystals in joints. However, exactly why these deposits occur is unknown. Diet and the intake of certain calcium-rich substances, such as milk, do not increase the risk of getting pseudogout attacks. However, there are several other factors thought to be associated with the formation of CPPD deposits and pseudogout, including:

• Gout. Often occurs simultaneously with pseudogout. Crystal deposits associated with gout are made from uric acid, as opposed to pseudogout crystals, which are made from calcium. Furthermore, gout often affects the toes and feet, whereas pseudogout is more common in the knees. These two diseases are thought to be connected, although how or why is unclear.
  
  
• Joint trauma. People who have experienced severe joint trauma, including surgery such as a joint replacement (arthroplasty), have higher rates of pseudogout than others who have not. If evidence of CPPD deposits is found, a physician may seek information about a patient’s trauma history.

• Hypercalcemia (excessive calcium in the blood). Causes of hypercalcemia include hypothyroidism (underactive thyroid gland), hyperparathyroidism (overactive parathyroid glands), hemochromatosis (inherited disease marked by excessive storage of iron), hypomagnesia (magnesium insufficiency) or hypophosphatasia (inherited bone disease marked by insufficient phosphate). Other conditions that may increase the risk of pseudogout include acromegaly (gigantism), Wilson's disease (inherited disorder in which copper accumulates in the tissues) and ochronosis (condition marked by blue-black discoloration of tissues).
  
  
• Stress. Stress from medical illness may be a cause of pseudogout.
  
  
• Heredity. Family history of pseudogout increases the risk of developing the condition.