Hypocomplementemia

Introduction Urticarial vasculitis (Mruffie vasculitis) was first reported in 1973 by MCDuffie, which is characterized by a rash wheal that lasts for a long time with hypocomplementemia. Inflammatory mediators damage vascular endothelial cells, and thus vasculitis changes, showing the manifestations of leukocyte rupture vasculitis. The cause is unknown, and there are reports of hypersensitivity vasculitis caused by iodine allergy, repeated cold stimulation, and allergens such as viruses, bacteria, and parasites.

Cause

Etiology and pathogenesis: This disease is a new immune complex disease, the etiology and pathogenesis is extremely complicated.

1. Inducement

The factors that induce urticaria vasculitis are unknown. It has been reported that it is an allergic reaction such as a chemical substance or a drug (such as an iodine agent), repeated cold stimulation, and hypersensitivity vasculitis caused by an allergen such as a virus, a bacterium, or a parasite.

2. Damage to circulating immune complexes, anti-endothelial cell antibodies, and cellular immune responses

Antigen-antibody immune complexes cause C1q binding or activation under the action of low molecular weight precipitants, further leading to complement activation of traditional pathways, producing anaphylatoxins and neutrophil chemotactic factors. These inflammatory mediators can damage vascular endothelial cells, leading to the development of vasculitis. Some scholars pointed out that the relationship between this disease and connective tissue disease should be taken seriously.

3. Arthus reaction

Leukocyte fragmentation vasculitis (local skin reaction) caused by type III allergy mediated by IgG and IgM.

an examination

Related inspection

Skin smear microscopy skin microscopy

1, clinical manifestations

The main clinical manifestations of urticaria vasculitis are as follows:

1 The disease is more common in middle-aged women, and the age of onset is mostly between 30 and 40 years old. When it starts, it is often accompanied by irregular fever, sometimes up to 38 ~ 39 °C.

2 The main feature of the skin is the wheal, which is very similar to urticaria. However, the wind damage of the wind group lasts for a long time, often 24 to 72 hours, or even days. Consciously itchy or burning, the wind group is infiltrated, and sometimes spotted bleeding can be seen in the lesion. In a few cases, there are blisters, but no necrosis, and the pigmentation or desquamation remains after the damage subsides.

3 This disease is often accompanied by joint pain and arthritis, mainly found in the joints of the limbs, and sometimes joint swelling. There may also be abdominal discomfort, swollen lymph nodes, and the like. Kidney damage can occur in the advanced stage. In a few cases, epilepsy, meningitis and unilateral optic neuritis can occur. Vascular inflammatory urticaria is often an early symptom of dermatomyositis, allergic vasculitis, SLE, etc., so the course of disease should be closely observed.

2, diagnosis

Mainly based on clinical manifestations and laboratory tests to diagnose: clinical manifestations mainly for skin wheal lasting more than 24 hours, with fever, joint pain, abdominal pain, etc., swollen lymph nodes, severe cases may have kidney damage. Laboratory indicators: dermal endothelial cells are swollen, there are more neutrophils around the blood vessels, nuclear dust and red blood cells spilling out, and fibrin-like degeneration in the blood vessel wall. Rapid, severe and long-lasting hypocomplementemia. Histopathological examination revealed leukocyte fragmentation vasculitis. Direct fluoroscopy revealed Ig and complement deposition in and around the vessel wall.

Differential diagnosis

Differential diagnosis of hypocomplementemia:

1. Hypophosphatemia: Phosphorus metabolism disorder caused by lower than normal phosphate concentration in circulating blood. Also known as hypophosphatemia. The table is currently hemolysis, burnout, weakness and convulsions. The cause is fasting, long-term use of aluminum hydroxide, magnesium hydroxide or aluminum carbonate and other binding agents, glycolysis and alkalosis, hyperthyroidism, vitamin D deficiency, certain tubular diseases (such as Fanconi syndrome) ), alcoholism and anti-vitamin D rickets (familial hypophosphatemia).

2, hypoxemia: refers to the lack of oxygen in the blood, arterial partial pressure of oxygen (pao2) is lower than the normal lower limit of the same age, mainly as the blood oxygen partial pressure and blood oxygen saturation decreased. Adult normal arterial oxygen partial pressure (PaO2): 83-108 mmHg. A variety of causes, such as central nervous system disorders, bronchial, pulmonary lesions, etc. caused by ventilation and / or ventilation dysfunction can lead to hypoxia. Due to the degree of hypoxemia, the speed and duration of hypoxia, the impact on the body is also different. Hypoxemia is one of the most common critical illnesses in respiratory diseases and one of the important clinical manifestations of respiratory failure.

3. Proteinemia: refers to the reduction of total plasma protein, especially plasma albumin. Mainly manifested as malnutrition. The proteins in the blood are mainly plasma proteins and hemoglobin contained in red blood cells. Plasma proteins include plasma albumin, various globulins, fibrinogen and a small amount of binding proteins such as glycoproteins, lipoproteins, etc., in a total amount of 6.5 to 7.8 g%. If the total plasma protein is less than 6.0 g%, it can be diagnosed as hypoproteinemia.

4, hypomagnesemia: normal into the plasma magnesium content of 0.8. ~ 1.05mmol / L, plasma magnesium below 0.75mmol / L for hypomagnesemia. Plasma magnesium exists in three forms. 1 free magnesium: about 55% or more; 2 complex magnesium: a complex of magnesium and bicarbonate, phosphate, etc., about 15%; 3 protein-bound magnesium: mainly combined with albumin, about 30% . Muscle tissue has the highest magnesium content in tissues, accounting for about 80% of the nuclear content of nuclear cells. In acute magnesium deficiency, plasma magnesium is low and muscle magnesium content does not change much, but in chronic magnesium deficiency, plasma magnesium is normal and muscle magnesium content is reduced. The magnesium concentration of red blood cells is earlier than that of muscle when magnesium is deficient, so red blood cell magnesium can be used as an important indicator to reflect magnesium deficiency in the body. Magnesium is absorbed by the intestines and is mainly excreted by the kidneys. Thyroxine, parathyroid hormone, growth hormone and vitamins all promote the absorption of magnesium in the intestines and kidneys, contrary to the effects of aldosterone. Insulin promotes the entry of magnesium into cells. Magnesium has many important physiological functions. For example, magnesium is an activator of many enzyme systems in cell metabolism. It is necessary to maintain the integrity of DNA helix and ribosomal particle structure. Magnesium has the function of maintaining normal myocardial metabolism and myocardial excitability. Important role.

5, hypocalcemia: normal serum total calcium is quite constant, 2.25 ~ 2.75mmol / L, children are high. Calcium in plasma and body fluids is mainly present in combination with calcium and free calcium. The former is mainly combined with albumin, and a small amount is combined with organic acids, such as calcium citrate, calcium lactate, and calcium phosphate. Free exchange of calcium with bound calcium is in a dynamic equilibrium, which is mainly affected by pH. In the case of acidemia, free calcium (Ca2+) increases and vice versa. In addition, a certain product is maintained between blood calcium and blood phosphorus concentration, that is, [Ca] × [P] = 350-400 mg / L. Only free calcium really has the physiological function of calcium. Calcium calcium below 2.2mmol / L is called hypocalcemia.

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