Under normal conditions, the intracellular and extracellular calcium ion concentrations are kept in dynamic balance. Modern medical research has found that when intracellular calcium ion concentration continues to increase, causing cellular excitation-contraction decoupling, it will lead to hypertension, myocardial infarction, heart failure, sudden death and other diseases, recently called intracellular “calcium deposition” or “calcium in-flow This has recently been termed intracellular “calcium deposition” or “calcium in-flow”. So, how is the differential diagnosis of calcium deposits made? The following is an introduction to the differential diagnosis of calcium deposits: 1. Diseases differentiated from pseudogout: clinically, pseudogout is mainly a manifestation of acute synovitis patients can have fever can involve one or several joints, the surface of the affected joint is often accompanied by erythema of the skin, when the disease is secondary to joint trauma or other joint diseases, especially when the joint fluid contains a large number of white blood cells need to be differentiated from septic arthritis, the joint fluid Gram staining and culture of the joint fluid are necessary to diagnose the latter, while pseudogout can be diagnosed if calcium pyrophosphate crystals are found microscopically. It is important to note that septic arthritis can sometimes coexist with crystalline synovitis in clinical practice. Acute gout is another disease that requires a differential diagnosis, and microscopic examination of the joint fluid is the best way to distinguish between the two diseases. Sometimes, the high number of erythrocytes in the joint fluid of this disease should be distinguished from some joint diseases with joint effusion, especially the joint effusion due to rupture of blood vessels caused by subchondral fractures, in which the joint fluid is often positive for Sudan III staining without deposits of calcium pyrophosphate crystals. Sometimes the diagnosis of pseudogout is clear, and the symptoms of synovitis are obviously relieved after treatment, but the patient still has localized tenderness in the joint, it is necessary to be alert to the possibility of the combination of the two, and then it is necessary to look for fracture lines on X-rays to provide clues. 2, and chronic pyrophosphate arthropathy to distinguish the disease (1) and type B (pseudorheumatoid arthritis) to distinguish the disease: in elderly patients some involved in multi-joint arthritis of this type can have a mild increase in blood sedimentation, then the disease needs to be distinguished from rheumatoid arthritis because the latter occurs in the elderly often with large joint lesions, in addition to arthroscopic examination of the joint fluid to find calcium pyrophosphate crystals, with the following clinical manifestations can be distinguished from Rheumatoid arthritis can be distinguished from rheumatoid arthritis by the following clinical manifestations: (1) this type of arthropathy is rarely associated with tenosynovitis; (2) there are almost no serious extra-articular manifestations of this type; (3) pars plana osteoporosis or bone destruction is less common than rheumatoid arthritis; (4) serum rheumatoid factor is mostly negative; (5) there is typical cartilage calcification on X-ray. If the patient is accompanied by stiffness of proximal joints, it is also necessary to differentiate it from rheumatic polymyalgia. In addition to careful systematic physical examination and joint fluid and X-ray examination, sometimes diagnostic treatment is required to differentiate it. (2) Diseases differentiated from type C and D (pseudo-osteoarthritis): Osteoarthritis is the most common disease that needs to be differentiated from this disease. Pseudo-osteoarthritis can occur in areas rarely affected by osteoarthritis, such as the wrist, elbow, shoulder and interphalangeal joints, while the knee joint is predominantly posterolateral, with more intense inflammation than osteoarthritis; ② pseudo-osteoarthritis can have acute attacks; ③ calcium pyrophosphate crystals can be found in the joint fluid of pseudo-osteoarthritis; ④ the typical manifestation of pseudo-osteoarthritis on X-ray is cartilage calcification, accompanied by bone redundancy or cyst formation. In addition, compression or fracture of subchondral bone may be seen on X-ray, accompanied by degenerative joint changes such as formation of high-density intra-articular debris; ⑤ pseudo-osteoarthritis mostly has the formation of subchondral cysts. (3) Diseases differentiated from type F (pseudoneuropathic arthritis): Although this type can be very similar to neuropathic arthritis on X-ray, its clinical manifestations are much more severe than Charcot arthritis and the neurological examination and serological examination of this disease are often normal. (4) When the disease involves the pars interarticularis and causes calcification, it needs to be differentiated from soft tissue calcification caused by some tumors, and sometimes a tissue biopsy is required to make a definitive diagnosis.