Overview of Erythropoiesis
Plateau erythrocytosis (referred to as “polycythemia vera”) is a chronic highland disease caused by excessive compensatory erythropoiesis (i.e., overproduction of erythrocytes) due to the low-oxygen environment of the plateau. Compared with healthy people at the same altitude, erythrocytes, hemoglobin, hematocrit increase significantly, arterial oxygen saturation decreases, and is accompanied by clinical symptoms and signs of polycythemia. The disease is more common in people who have migrated to the plateau and less common in people who have lived there for a long time.
Causes
Hyperthyroidism is caused by excessive erythrocyte proliferation due to tissue hypoxia, and chronic low-pressure hypoxia is the underlying cause of the disease. The increase of erythrocytes, on the one hand, increases the oxygen-carrying capacity; on the other hand, it increases the blood viscosity and slows down the blood flow, which leads to the decrease of perfusion in all organs and tissues, and aggravates the hypoxia, forming the vicious circle of “hypoxia – erythrocytes increase – aggravate hypoxia – erythrocytes further increase – hypoxia”. Living in the plateau area of the crowd long-term smoking will hinder the transmission of oxygen, reduce tissue oxygen uptake, aggravate hypoxemia, thus inducing the occurrence of hypercapnia. In the plateau area, obesity, nighttime sleep and breathing disorders and other factors are also prone to induce excessive red blood cell proliferation, the same principle as the above, also prone to lead to the generation of hyperthyroidism.
Symptoms
The clinical symptoms of this disease vary in severity and complexity. Some foreign scholars summarize the main symptoms and signs of hyperthyroidism as headache, shortness of breath, fatigue, depression, palpitations, sleep disorders, tinnitus, poor appetite, cyanosis, conjunctival capillary congestion and dilatation, muscle and/or joint pain, pestle fingers (toes), numbness of the fingers and toes, and sensory abnormalities.
1. Symptoms
Similar to plateau reaction, some scholars in China summarize its common symptoms as dizziness, headache, shortness of breath, chest tightness, abdominal distension, abdominal pain, fatigue, arthralgia, anorexia, lethargy, memory loss, insomnia, and sometimes numbness or distension of hands and feet. Some patients may have nosebleeds, bleeding gums, bleeding spots or petechiae on skin mucosa. Severe patients may have severe headache and vomiting, and may also have different degrees of impaired consciousness. In addition, symptoms such as irregular menstruation in women, erectile dysfunction in men, and loss of libido have also been reported.
2. Physical signs
Cyanosis is the main sign of the disease, and most patients have different degrees of cyanosis. The lips, cheeks, edges of the ears, finger (toe) nail beds and other parts are cyanotic, and the facial capillaries are dilated with purplish-red streaks, forming the unique face of this disease, i.e., “plateau polycythemia face”. The conjunctiva of the eye is highly congested, the tongue is purple, the tongue moss is thick and dry, the mucous membrane of the tongue and throat is black or greenish-purple, some patients have pestle finger and nail depression; some patients have facial and lower limb edema, the liver and spleen may be enlarged, the heart rhythm is generally regular, a few people have bradycardia or sinus arrhythmia, in some cases, the apical region and the area of the pulmonary valve may be audible as a grade I-II murmur, the pulmonary artery has a hyperactive or splitting of the Ⅱ tone, the blood pressure may be high or low, the pulse pressure difference is small, the blood pressure may be high or low, and the pulse pressure difference is small. The blood pressure may be high or low, and the pulse pressure difference is small.
Examination
1. Blood tests
The red blood cell count in the blood is abnormally high, and the hemoglobin concentration is also abnormally high. China’s diagnostic criteria for hyperhemoglobinopathy are: hemoglobin count ≥200g/L for men and ≥180g/L for women; hematocrit ≥0.65 for men and ≥0.60 for women; erythrocyte count ≥6.5×1012/L for men and ≥6.0×1012/L for women; the total number of leukocytes and their classifications are in the normal range, and the platelet counts are the same as that of the healthy people in the same altitude; the bone marrow granulocyte system is characterized by an abnormally high erythrocyte concentration, and a low blood pressure. The main feature of bone marrow granulocyte system was the proliferation of erythrocyte system, in which the proliferation of late juvenile erythrocytes was obvious, and there was no obvious change in granulocyte and megakaryocyte system.
2. Blood gas analysis
In patients with hypercoerythrocymia, the pH was reduced, and blood gas analysis showed significant hypoxemia, with decreased PaO2, increased PaCO2, increased A-aDO2 (alveolar gas arterial blood oxygen partial pressure difference), and relative hypercapnia; there were no significant changes in lung function except for mild abnormalities in small airway function, which was manifested in the patients with decreased closed air volume (CV/VC%) and decreased forceful expiratory mid-expiratory flow (FEF25%-75%). FEF25% to 75%) were decreased.
3. Gastroscopy
Due to the increase of blood viscosity, blood flow is slow, which directly affects the microcirculation of gastric mucosa, and due to the formation of thrombus in the capillaries in the hypercoagulable state of the blood, the gastric mucosa is severely ischemic and hypoxic, which can easily lead to hemorrhage, erosion and necrosis of the mucosa.
4. Electrocardiography
Right ventricular hypertrophy is the main manifestation, with rightward deviation of electrical axis, extreme clockwise transposition, pulmonary P wave or spike P wave, complete or incomplete right bundle branch block, right ventricular hypertrophy with myocardial strain, etc. Only a few patients have PR and QT interval prolongation and biventricular hypertrophy, and there is a positive correlation between right ventricular hypertrophy and pulmonary arterial hypertension.
5. X-ray examination
In case of pulmonary hypertension and plateau heart disease, right ventricular enlargement, convexity of pulmonary artery segment and increase in diameter of right lower pulmonary artery will be seen.
Diagnosis
Diagnosis can be made on the basis of symptoms, signs, and laboratory tests. The diagnostic criteria are:
1. migrants living on a plateau at an altitude of 3000 meters or more, or a few worldly residents.
2. symptoms such as headache, dizziness, shortness of breath, fatigue, sleep disturbance, cyanosis, and congestion of the conjunctiva of the eye.
3. Hemoglobin count, male ≥200g/L, female ≥180g/L; hematocrit, male ≥0.65, female ≥0.60; red blood cell count, male ≥6.5×1012/L, female ≥6.0×1012/L.
4. Symptoms and signs disappear after leaving the hypoxic environment, and then recur when returning to the plateau.
5. Rule out other causes or diseases causing erythrocytosis.
Treatment
The underlying cause of hyperthyroidism is excessive erythropoiesis caused by tissue hypoxia. Therefore, the most effective treatment is to get out of the hypoxic environment. Based on its pathogenesis, the basic treatment principles are:
1. General treatment
In addition to individual differences in hypoxia, exertion, cold and respiratory infections are often the triggering factors for patients with hyperhidrosis. Therefore, patients with hyperhidrosis in plateau should pay attention to the combination of work and rest, to ensure sleep time and sleep quality, appropriate physical exercise. Cardiac insufficiency should pay attention to bed rest. Adjust the diet, eat more fruits and fresh vegetables, prohibit smoking and excessive alcohol consumption. [1]
2. Oxygen therapy
Oxygen therapy is an important means of correcting hypoxia, increasing oxygen saturation and improving cardiac function. Oxygen according to the condition of intermittent or continuous low-flow (1 liter / min) oxygen, generally do not have to apply high concentration of oxygen, in order to raise the PaO2 to 50mmHg, SaO285% or more appropriate.
3. Cardiotonic and diuretic
Cardiotonic agents can be used for those with heart failure, such as cediran and digoxin. And can be combined with hydrochlorothiazide, furosemide and so on.
4. Reduce pulmonary artery pressure
If hyperhidrosis is complicated by pulmonary hypertension or plateau heart disease, aminophylline or phentolamine can be used as appropriate. [2]
5. Antibiotics
Antibiotics may be used if the patient has a respiratory tract infection. [3]
6. Removal from plateau environment
Where the heart is obviously enlarged, there is obvious pulmonary hypertension and serious cardiac insufficiency patients as soon as possible to the plains or lower altitude treatment. [4]
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