Gout is a disorder in which uric acid crystals accumulate in the joints. The sharp edges of these crystals irritate the soft tissue of the joints, and cause inflammation and pain. Uric acid crystals are the waste products formed when purines, which are part of the nucleic acids that make up the genes, break down. A number of other conditions can cause symptoms similar to those of gout.
Gout commonly affects a single joint initially, most often the joint of the big toe. Hydroxyapatite pseudopodagra is a disorder that manifests via a similar pattern of pain and swelling in the first metatarsophalangeal joint, which is the joint where the big toe meets the bones of the foot. The symptoms closely resemble gout, but differ in that they most commonly affect young women, while gout is more frequently associated with women of postmenopausal age.
Hydroxyapatite pseudopodagra differs from gout in that the crystals that form in the big toe are composed of calcium hydroxyapatite, not deposits of uric acid as is the case in gout.
Pseudogout is another disease that results from crystalline deposits that gather in the joint. In this condition, calcium pyrophosphate crystals are involved, forming deposits called chondrocalcinosis. Pseudogout affects some of the same joints that are typically involved in gout, such as the ankles, toes and knees, but can also affect areas not usually touched by gout, such as the shoulders and hips.
The pain of pseudogout is not as severe as that of gout, but similarly to gout, it can cause lifelong symptoms and result in joint damage.
Osteoarthritis occurs due to wear on the joints over time, or due to damage to the joint caused by trauma. This condition is often confused with gout, and can actually coincide with gout, according to the University of Maryland Medical Center. The crystalline uric acid deposits that become lodged in the capsule of a joint can impinge on joint movement, or damage cartilage or bone tissue, leading to the formation of bone spurs or the erosion of the joint surface.
Diabetics frequently experience damage to the nerves of the foot due to their disease. Charcot foot, also known as neuropathic arthropathy, is a condition that results from such nerve damage. Charcot foot manifests with symptoms such as swelling and inflammation of the foot. The University of Maryland Medical Center warns that this condition can lead to foot deformity.