Amyloidosis

Introduction Amyloidosis, also known as starch-like deposition, refers to a variety of conditions that cause amyloid protein to deposit abnormally in body organs or tissues. It is a general term for a group of rare diseases. Amyloid is a form of insoluble polymerization similar to beta-sheets due to changes in its secondary structure. The signs of starch deposition vary depending on where the amyloid deposits are located, and the causes of these diseases may be acquired or genetic.

Cause

The reason for the deposition of amyloid products and the tissues in which they are located is unclear. In different biochemical types of amyloidosis, the etiology may be different, such as secondary amyloidosis as a metabolic disorder of protein precursors (acute phase). The reactant plasma amyloid A), while the hereditary amyloidosis produces different proteins. In primary amyloidosis, a monoclonal population of bone marrow cells produces fragments or entire long chains that form amyloidosis. Under light microscopy, amyloid is homologous, highly affinitive, and has affinity for Congo red dye in fixed tissues.

an examination

Peripheral blood

Hemoglobin, white blood cell count and classification, platelets are generally normal, only 11% of patients with hemoglobin <100g / L, which is related to myeloma involving bone marrow, renal insufficiency or gastrointestinal blood loss. About 9% of patients have platelet counts >500×109/L. The spleen function is caused by the precipitation of amyloid.

2. Biochemical examination

Some patients have an increase in alkaline phosphatase, which is considered to be caused by congestive heart failure, in addition to considering liver involvement. Transaminase bilirubin is in the normal range, and some patients may see an increase. If there is a significant increase, it often indicates that the disease has reached the advanced stage. Half of those with nephrotic syndrome have elevated cholesterol and some have elevated triglycerides. In addition, 5% of patients had X-factor defects, but rarely caused bleeding. In some patients, serum creatinine was 180 mol/L, and half of the patients were completely normal.

3. Serum protein

About half of patients with primary amyloidosis can see monoclonal protein in protein electrophoresis. If further electrophoresis or immunofixation is used, the positive rate can reach 72%. The median M protein 14g / L (M protein) a few > 30g / L, about one-four patients with aggreglobinemia. / is 1:2.3.

Differential diagnosis

According to the symptoms and signs described above, the initial diagnosis of amyloidosis can only be confirmed by biopsy. Subcutaneous abdominal fat pad aspiration and rectal mucosal biopsy are the most commonly used screening methods. Other useful biopsy sites are gums, skin and nerves. , kidney and liver. The green birefringence characteristics of amyloidosis were observed under polarized microscopy in tissues stained with Congo red. Amyloidosis can be confirmed by a scintillation test using isotopically labeled serum AP.

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