General inspection
Blood routine Blood routine examination is basically required for patients with acute fever to help doctors preliminarily determine whether the patient is infected, the possible pathogen type of infection, and the severity of infection. Sometimes, it is one of the indicators for doctors to judge whether antibiotics are necessary.
The typical hematologic features of HFRS are "three high and one low". ① Increased white blood cell count, increased hemoglobin, lymphocyte increase, often because of a large amount of plasma exudation, blood concentration; Some patients with systemic leukocyte mobilization, greatly increased, leukemia-like performance, easy to make people mistake for hematological system tumor. ② A large number of abnormal lymphocytes appeared in peripheral blood, suggesting that the disease may be caused by virus infection. ③ Thrombocytopenia, but with a certain specificity. Thrombocytopenia in patients with atypical acute fever in endemic areas needs to be considered for hemorrhagic fever with renal syndrome, which can help doctors screen atypical cases. At the same time, the degree of thrombocytopenia is also related to the severity of the disease and the risk of visceral hemorrhage. Therefore, during the whole process of the disease, doctors will closely observe the changes of platelets dynamically to determine the direction of the disease development, and active intervention measures should be taken when necessary. Peripheral blood platelet count below 20×109/ l usually indicates severe disease. Critically ill patients need daily blood tests until platelets rise to safe levels.
Routine urine routine urine routine is a relatively simple, inexpensive non-invasive test, commonly used to preliminarily judge whether the urinary system has abnormal function, usually can distinguish between frequent urination, urgent urination, urination pain and other urinary tract irritation patients with urinary tract infection. In patients with typical kidney disease, such as low back pain, urine volume change and foamed urine, doctors often require patients to complete routine urine examination to determine whether renal function is damaged. For patients with hemorrhagic fever with RENAL syndrome with typical manifestations of "three red and three pain", doctors usually complete routine urine examination at the first time. Urine protein can appear on the second day of the disease course, and urine protein often reaches +++ ~ ++++ on the 4th to 6th day of the disease course. The sudden appearance of a large amount of urine protein is very helpful to the diagnosis, urine microscopic examination can see red blood cells, white blood cells and tubular type; Some severe patients had visible membrane in their urine. In the absence of urinary system performance is not a typical patients with mild and early is not the patients with symptoms of urinary system, the epidemic areas of if patients with fever of unknown causes thrombocytopenia, also can consider to improve urine routine examination, in order to help distinguish whether could be kidney syndrome hemorrhagic fever, and if there is any need to improve the kidney syndrome hemorrhagic fever etiology examination. The abnormality of urine routine reached its peak in oliguria stage and turned negative in polyuria stage and recovery stage.
Blood biochemistry
Liver function HFRS patients may have elevated liver enzymes and decreased human serum albumin. But these are secondary changes, there is no need to worry, as the disease recovers, liver function will naturally improve.
Renal function Renal function is an important index to distinguish the severity and recovery of diseases. Serum urea nitrogen and creatinine in HFRS patients began to increase in hypotensive shock stage, peaked in oliguria stage, and gradually decreased in recovery stage. Patients with serum creatinine rising to more than 3 times the normal value or urea nitrogen significantly increased need hemodialysis treatment, kidney function is also one of the important indicators for doctors to evaluate whether patients can be discharged.
Electrolytes Electrolytes are also one of the indicators that doctors focus on to help identify acid-base imbalance, hyperpotassium, or hypokalemia. The febrile period presents as respiratory alkalosis (associated with hyperventilation); Shock stage and oliguria stage were metabolic acidosis, blood sodium, chlorine, calcium decreased; Blood potassium was low in fever and shock stage and increased in oliguria stage. Hypokalemia was easy to occur in polyuria stage. Monitoring of electrolytes during treatment is extremely important. Severe electrolyte disturbances can be life-threatening. Hyperkalemia, in particular, can lead to cardiac arrest. Blood potassium ion & GT; Hemodialysis is recommended as soon as possible for patients with 6.5 mol/l.
Coagulation function test
In febrile period, thrombocytopenia begins, and its adhesion, coagulation and release functions are reduced. In the case of diffuse intravascular coagulation (DIC), thrombocytopenia often decreases to less than 50×109/ l. Coagulation time was shortened in DIC hypercoagulable stage, fibrinogen was decreased and prothrombin time was prolonged in consumptive hypocoagulable stage, and fibrin degradators were increased in DIC hyperfibrinolysis stage.
Coagulation function is one of the indicators to judge the risk of bleeding and the severity of disease. As the coagulation mechanism in blood is diffusely activated, fibrinogen deposition in small blood vessels is promoted, leading to tissue and organ damage. On the other hand, the consumption of clotting factors causes systemic bleeding tendency. In patients whose DIC has been initiated, the multiple organ dysfunction syndrome is the leading cause of death.
A positive test for hantavirus specific IgM antibody can confirm present or recent infection. However, a negative test does not rule out HFRS, and suspected cases that test negative can be tested daily or every other day. Specific IgM antibody (1:20 positive) can be detected on the second disease day, and the positive rate is more than 90% on the 4th to 6th disease day, and close to 100% on the 7th disease day. A small number of clinical cases with atypical symptoms, but specific IgM antibody positive. Hantavirus specific IgG antibody 1:40 is positive, but a single positive IgG cannot distinguish recent infection or previous infection, and the diagnostic value is only when the titer increases by 4 times or more after 1 week. Immunological examination is a cheap, rapid and accurate diagnostic method.
For patients with typical "three redness and three pain" in epidemic areas, doctors will improve this test in the first time to confirm the diagnosis. For patients with acute fever of unknown thrombocytopenia or patients with thrombocytopenia accompanied by positive urinary protein, doctors will also improve the antibody test of epidemic hemorrhagic fever as soon as possible.
Molecular biological approach
Nestlander RT-PCR can detect Hantavirus RNA with high sensitivity and diagnostic value. However, viremia exists in vivo for a short time and the positive rate after the fever period is low, so it is not commonly used in clinical practice.
virus isolation
Hantavirus can be isolated by inoculating serum, blood cells and urine of patients in febrile stage into V-ERO-E6 cells or A549 cells. However, due to the short duration of viremia, it is not commonly used in clinical practice.
Other tests
In the acute stage of abdominal ultrasonography, renal enlargement was seen, suggesting the possibility of acute renal edema.
Pulmonary edema can be seen on chest X-ray or CT in 30% of patients. The incidence of pulmonary edema was 47% in the hypotensive shock phase and up to 68% in the oliguria phase.
Ecg patients with hyperkalemia will appear T wave high apex, hypokalemia U wave, part of the patients can appear sinus bradycardia.
Patients with neurological symptoms and signs are treated with a head CT to help assess intracranial hemorrhage.
The purpose of all tests is to help confirm the diagnosis, determine the trend/severity of the haemorrhagic fever, and guide the treatment plan.
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