Hemolytic anemia due to lead poisoning
Introduction
Introduction to hemolytic anemia caused by lead poisoning The toxicity of lead is more obvious, which can affect the multi-organ system in the body, and the impact on the hematopoietic system is particularly significant. It is the most common cause of hemolytic anemia in occupational and life poisoning. basic knowledge The proportion of sickness: 0.01--0.03% Susceptible people: no specific population Mode of infection: non-infectious Complications: anemia
Cause
Causes of hemolytic anemia caused by lead poisoning
(1) Causes of the disease
Lead is silver-white metal, slightly light blue, high density, can be used to determine the relative density, soft, and malleable, can be rolled into lead without heating, lead foil, melting point is not high, Can be used as a fuse, lead is corrosion resistant, used in chemical equipment and cable sheathing, lead is easy to alloy with other metals, such as typeface, bearing tiling, can improve metal properties, lead mining and smelter frequent exposure to lead dust And lead smoke, the contact with the lead is the production and repair of the battery.
Among the common lead compounds, lead dan, lead chrome yellow, lead white are used as paint pigments, ceramic glazes, lead arsenate is used as a pesticide, tribasic lead sulphate, and dibasic lead phosphite is used as a plastic stabilizer. Lead compounds are also used as drugs, such as bismuth (Pb3O4), black tin dan, etc. for the treatment of epilepsy, asthma, etc. In life, tin cans (mainly lead-tin alloy) wine or tea, often can cause severe illness Lead poisoning; lead poisoning can occur in utensils coated with lead glaze on the inside, and exhaust gas from cars with leaded gasoline can pollute the environment. According to the lead determination of ice specimens collected in Icelandic icebergs, lead in today's industrialized era Environmental pollution is becoming more and more serious, and prevention of lead poisoning should be carried out in parallel with industrial development.
(two) pathogenesis
The mechanism of lead poisoning causing anemia has two aspects:
Hemoglobin synthesis disorder
(1) Inhibition of heme synthesis: Lead inhibits the synthesis of heme by inhibiting several related enzymes of porphyrin metabolism during heme synthesis (Fig. 1), and lead inhibits -amino--ketovalerate dehydratase (ALAD) ), the formation of scorpion bilirubin is inhibited, lead inhibits coproporphyrinogen oxidase, causing the content of fecal porphyrin in the blood to be excreted in the urine, and lead inhibits heme synthetase, so that the ferrous iron cannot be incorporated into the original Porphyrin, which hinders the synthesis of heme, reduces the synthesis of heme by feedback, stimulates -amino--ketovalerate synthase (ALAS) to increase the synthesis of -amino--ketovaleric acid (ALA) in blood, and Excreted from the urine, because the ferrous iron can not be incorporated into the original porphyrin to form heme, too much protoporphyrin in the red blood cells combines with zinc to form zinc protoporphyrin (ZPP), which has fluorescence for easy detection, and excess iron particles In the red blood cells that accumulate in the maturation process, bone marrow examination shows iron mitochondria around the nucleus of the young red blood cells, which is called "annular iron granule cells".
(2) globin synthesis disorder: lead has obvious inhibitory effect on the synthesis of globin, mainly interferes with the synthesis of and chains of globin, making its synthesis asynchronous, and lead can also promote hemoglobin decomposition. These changes may be The hemoglobin undergoes a conformational change.
2. Hemolysis of lead
(1) The effect of lead on erythrocyte fragility, morphology and deformability: lead and human red blood cells, red blood cell mechanical fragility, its mechanism may be related to lead-induced hemoglobin changes, which in turn affect erythrocyte membrane, lead workers with anemia It can be seen that the erythrocytes of spherical and abnormal morphology increase, and the red blood cell deformability of lead workers is significantly reduced, which is prone to hemolysis.
(2) Effect of lead on erythrocyte membrane permeability: Lead acts on erythrocyte membrane, which changes membrane permeability, leading to destruction of red blood cells, lead inhibits erythrocyte membrane Na / K -ATPase and Ca2 / Mg2 - ATPase The activity is due to the fact that lead can directly bind to the sulfhydryl group of the enzyme protein to inhibit the activity of the enzyme. Lead into the cell can reduce ATP and indirectly reduce the enzyme activity. Due to the inhibition of the above membrane ion pump, the leakage of red blood cell K increases and the water loses. The cells shrink; at the same time, the intracellular Ca2 rises, which makes the Ca2-dependent K channel open, promotes the leakage of K, and causes hemolysis.
3. Lead inhibits pyrimidine 5'-nucleotidase (P5N) activity. Lead inhibits P5N activity, so that the 5'-nucleotide of reticulocytes can not be degraded and gradually accumulate, and aggregates in the cytoplasm to form alkaline red blood cells. The increase of 5'-nucleotide of pyrimidine can inhibit the function of pentose phosphate pathway by inhibiting the activity of G-6-PD, making lead poisoning red blood cells more susceptible to oxidant damage and hemolysis, chronic chronic anemia caused by long-term exposure to low concentration lead Lead inhibits heme synthesis; short-term exposure to high concentrations of lead caused by acute anemia, in addition to hemoglobin synthesis disorders, but also related to hemolysis, some of the above indicators of lead poisoning anemia can also be used as an indicator for the diagnosis of lead poisoning.
Prevention
Prevention of hemolytic anemia caused by lead poisoning
Good work and living environment to reduce environmental pollution and lead exposure energy.
Complication
Complications of hemolytic anemia caused by lead poisoning Complications anemia
There are no other special complications except for anemia.
Symptom
Symptoms of hemolytic anemia caused by lead poisoning Common symptoms Nausea bloating pale pale fatigue constipation Abdominal tenderness
Workers working in a better working environment may have only elevated urine lead and asymptomatic. Long-term exposure to low concentrations of lead may have mild neurological symptoms such as dizziness, headache, fatigue, limb aches, and digestive system. Symptoms, such as abdominal distension, abdominal pain, constipation, etc., when exposed to high concentrations of lead, abdominal cramps, anemia and peripheral neuropathy, working in harsh conditions, lead paralysis can also occur, the earliest literature mentioned in the phrenic nerve Paralysis, lead encephalopathy is currently rare.
Patients with chronic lead poisoning have recently been exposed to higher concentrations of lead dust and lead smoke, and acute lead poisoning episodes with abdominal cramps may also occur.
Living lead poisoning can be seen as severe lead poisoning, such as taking Qidan for epilepsy, and black tindan for treating asthma. After 2 to 3 weeks of continuous medication, nausea, loss of appetite, constipation, abdominal cramps, mild jaundice, Obvious anemia, numbness of hands and feet, weakness, physical examination to see pale, jaundice, gingival margin lead line, liver, abdominal tenderness, there may be limb extremity sensation, hand extensor weakness, this poisoning is subacute lead poisoning, Abdominal colic is characterized by anemia, liver disease and peripheral nerve damage, which is also common in alcoholic or tea drinkers who use tin pots for wine or tea.
Examine
Examination of hemolytic anemia caused by lead poisoning
1. Peripheral blood chronic lead poisoning patients 25% have anemia, anemia occurs later, from mild to moderate, is a mild hypochromic small cell anemia, acute lead poisoning hemolysis, anemia appears rapidly, reticulocytes and alkali Sexual red blood cells increased.
2. Red blood cell osmotic fragility is normal and mechanical fragility is increased.
3. Electrophoresis shows "fast" hemoglobin similar to hemoglobin A3, and some patients have increased levels of hemoglobin A2 and F.
4. Bone marrow examination often shows erythroid hyperplasia, but it can also be proliferated and low. Bone marrow smear iron staining can be seen in ring-shaped iron granule cells.
5. Red blood cell life is shortened, serum iron levels are normal or slightly increased, and iron dynamics studies are consistent with ineffective red blood cell hematopoiesis with mild hemolysis.
6. Porphyrin metabolism index check
(1) The two indicators of urinary -amino--ketovaleric acid (ALA) and urinary porphyrin are not sensitive enough, which is not ideal for early diagnosis of lead poisoning.
(2) Blood ALAD: It is too sensitive to lead and can be used as an environmental evaluation index. It should not be used as a diagnostic indicator.
(3) Free erythrocyte protoporphyrin (FEP) and erythrocyte zinc protoporphyrin (ZPP): the two have the same meaning and have a good linear correlation with blood lead. FEP and ZPP are sensitive to early lead poisoning or lead absorption. Biochemical indicators are a sensitive indicator of the body's response to lead. The determination of ZPP by fluorometer is fast, simple, economical and reliable.
7. Lead determination
(1) urinary lead: can reflect the recent lead exposure and lead absorption in the body, but sometimes not parallel.
(2) Lead-in test: Determination of lead in urine: It has a positive value for the diagnosis of lead poisoning and can reflect the lead load in the body.
(3) Blood lead: It can reflect the recent lead exposure, which is relatively stable and related to other biological indicators. Blood lead is a good indicator for the diagnosis of lead poisoning.
(4) Lead, the practical value of lead lead has not been confirmed, not suitable for census.
The order of change of indicators after exposure to lead is that urine ALA and coproporphyrin decrease within a few weeks, ZPP takes several months to become normal, and the biological half-life of blood lead is 30 days. The inhibition of ALAD can be For a long time, the biological half-life of bone lead can exceed 20 years, and the three values of lead poisoning diagnostic indicators are shown in Table 1.
Diagnosis
Diagnosis and diagnosis of hemolytic anemia caused by lead poisoning
According to the exact occupational history and clinical manifestations and related laboratory tests based on nerve, digestion, and blood system damage, the occupational lead poisoning can be diagnosed after comprehensive analysis.
Occupational lead poisoning should be identified with the following diseases:
1. The symptoms of lead poisoning in life are similar and heavier, but the history of lead exposure is different, mostly caused by taking medicine and drinking with tin pot.
2. Acute intermittent hematoporphyria can have severe abdominal cramps, accompanied by neuromuscular disorders, urinary purple bilirubin (PBG) is significantly increased, and urine lead emissions are not increased.
3. Iron deficiency anemia red blood cell ZPP increased, but less than lead poisoning, urine lead determination is helpful for differential diagnosis.
