The patient, a 17-year-old female, was admitted to the hospital with fever of unknown origin and was later diagnosed with infective endocarditis and given cefmetazole sodium (2 g, tid) and amikacin (0.4 g, qd) intravenously. After 7 days of treatment, the body temperature was normal and all other tests were normal, but the routine blood test showed leukocytes of 2.5×109/L.
Why is this patient’s white blood cell level still low after a period of antimicrobial therapy? Shouldn’t a patient with a normal infection have elevated white blood cells? After reading this article, maybe you will find the answer.
Routine blood tests, the first of the three routine tests, are one of the common tests used by doctors to diagnose medical conditions. The most commonly used items on a routine blood test include hemoglobin, red blood cell count, white blood cell count and white blood cell sorting count.
White blood cell count
White blood cell count (WBC) is normally 4.0~10.0×109/L in adults, 15.0~20.0×109/L in newborns, and 5.0~12.0×109/L in infants aged 6 months to 2 years.
1. Leukocytosis
The first thing that comes to mind with leukocytosis is the presence of infection, but you may not know that chronic leukemia, malignancy, uremia, diabetic ketoacidosis and acute poisoning from chemical drugs can also cause leukocytosis. Leukocytosis needs to be taken seriously enough because it can be a symptom of chronic leukemia, which, if not treated promptly, can lead to accelerated or acute lesions of slow-growing leukemia.
In addition to these pathological causes, there are also physiological causes such as leukocytosis around the time of menstruation, pregnancy, women during childbirth, strenuous exercise, excitement, and alcohol consumption. Therefore, when you see elevated white blood cells, do not jump to a diagnosis, it may be caused by physiological reasons.
2. Leukocytopenia
As a doctor, you may think of pathological diseases first, but be careful not to ignore physiological and pharmacological causes. Influenza, measles, granulocyte deficiency, cataracts and leukemia can all cause leukopenia. Of course, there are also some “false positives” that are easily overlooked.
When a patient is taking sulfonamides, antipyretics, some antibiotics (such as cephalosporins), antithyroid or antitumor drugs, it can cause leukopenia, which can be recovered by discontinuing them. For chemotherapy patients due to the adverse effects of chemotherapy drugs, there will also be a decrease in white blood cells, you can take some white-raising drugs.
3.White blood cell count
Leukocytes are a “large family”, divided into neutrophils, eosinophils, basophils, monocytes and lymphocytes.
The normal values of neutrophils are 50% to 70%, eosinophils 0.5% to 5%, basophils 0 to 1.0%, lymphocytes 20% to 40%, and monocytes 3% to 8%.
(1) Increased
The most common is neutrophilia, which, together with leukocytes, can be an indicator of infection because it is often caused by acute, septic infections. In contrast, normal leukocytes and high neutrophils are not necessarily an infection, as neutrophils fluctuate physiologically.
Of particular concern is the finding that patients with neutrophilia have a higher incidence of coronary heart disease, which is often severe, and a higher mortality rate in patients with cancer. In addition to pathological diseases that increase eosinophilia, there is also an increase when drugs such as midazapril, cefradine, and cefuroxime sodium are applied.
(2) Decrease
When patients have diseases such as typhoid fever and paratyphoid fever, it may cause a decrease in each cell of the leukocyte classification. And neutropenia is caused when patients take antineoplastic drugs, benzodiazepine sedatives, and antiepileptic drugs. And eosinophilic or basophilic granulocytopenia may occur with long-term application of drugs such as adrenocorticotropic hormone or candesartan.
Red blood cell count
Red blood cells are an important “player” in the blood, with normal values of (4.09~5.74)×1012/L for men and (3.68~5.74)×1012/L for women.
1. Erythrocytosis
In addition to unexplained chronic myelodysplasia causing true erythropoiesis, erythrocytes can reach up to (7~12)×1012/L. In addition to this there are some physiological causes that can lead to an increase in erythrocytes, such as an accelerated rate of erythrocyte release from the bone marrow during hypoxia and plateau life.
There is also a relative increase in red blood cells, when a large amount of water loss such as vomiting, diarrhea, excessive sweating, shock, etc., the amount of plasma is reduced, the blood is concentrated, then the concentration of each component in the blood increases accordingly. However, it is only a temporary phenomenon, and the red blood cells tend to normalize after the symptoms are relieved. Which can be measured by the red blood cell pressure product to understand the degree of blood concentration, as a clinical basis for the amount of rehydration.
2.Red blood cell reduction
Different causes of anemia such as aplastic anemia, blood loss anemia, etc. can cause a decrease in red blood cell count.
Hemoglobin
Hemoglobin (Hb) – the main component of red blood cells, its increase or decrease has the same clinical significance as the increase or decrease of red blood cells, and can better reflect the degree of anemia. The normal values are 131~172 g/L for men and 113~151 g/L for women.
1. Increased hemoglobin
Chronic pulmonary heart disease, true erythrocytosis, plateau disease and other pathological causes can cause hemoglobin increase. In cases of massive water loss and severe burns, hemoglobin increase can also be caused by blood concentration, but this condition requires special attention and may mask the symptoms of anemia.
There are also some conditions that are often easy to overlook, such as when patients take drugs such as sodium para-aminosalicylate, primaquine, vitamin K, nitroglycerin, etc., which can also increase Hb, so the effects of taking these drugs should be excluded when diagnosing the disease.
2.Decrease in hemoglobin
(1) The degree of hemoglobin reduction = the degree of red blood cell reduction, mostly seen when bleeding. And because hemoglobin can interact with certain substances to form a variety of hemoglobin derivatives, it can also be used to diagnose certain blood system diseases.
(2) The degree of hemoglobin reduction > the degree of erythrocyte reduction, which is mostly seen in iron deficiency anemia.
(3) Hemoglobin reduction < erythrocytopenia, most often seen in megaloblastic anemia.
Hemoglobin measurement can also provide a basis for determining the severity of anemia, with >90 g/L being mild, 60-90 g/L moderate, 30-59 g/L severe, and <30 g/L very severe anemia.
Platelet count
Platelets can produce a variety of platelet factors, which are involved in blood coagulation. Normal values are (100~300)×109/L for men and (101~320)×109/L for women.
1.Pathological causes
A variety of conditions can cause platelet reduction, such as bone marrow hematopoietic dysfunction, aplastic anemia, etc. will reduce platelet production. Cirrhosis and hypersplenism can cause excessive platelet destruction; splenomegaly and various causes of hemodilution can cause abnormal platelet distribution. In addition to pathological diseases that cause thrombocytopenia, there is also transient thrombocytosis seen in acute hemorrhagic anemia, post-spleen removal, fracture, post-hemorrhage and other traumas.
2, drug-induced thrombocytopenia
There are also some drugs that cause poisoning or allergy when taking some drugs can also make platelet reduction. For example, when taking chloramphenicol has a myelosuppressive effect, can cause thrombocytopenia; anti-platelet drugs such as aspirin can also cause thrombocytopenia; there are some anti-tumor drugs, antibiotics, sulfonamides can also cause thrombocytopenia.
So let’s go back to the case at the beginning of the article, it will be found that the patient’s leukopenia is more likely to be affected by cefmetazole drugs. Of course in routine blood tests, it is not the abnormality of one indicator that confirms the diagnosis of having a certain disease, but the combination of several tests is needed to support the evidence of a certain disease.