CBC：血红蛋白、白细胞和血小板

🧠 为什么重要

HEMOGLOBIN：男性约为14到18 g/dL，女性为12到16；HEMATOCRIT：男性为42到52%，女性为37到47%，约为血红蛋白的三倍。数值偏低意味着贫血或出血；是否输血通常在低于7到8 g/dL时考虑，具体取决于症状和心脏病史。即使红细胞总量不变，血细胞比容也会随脱水而升高，随液体负荷过重而降低。WHITE BLOOD CELLS：5,000到10,000/mm³；计数偏高提示感染、炎症、类固醇影响或白血病；计数偏低（leukopenia）见于化疗后、病毒性疾病或骨髓衰竭。A SHIFT TO THE LEFT意味着未成熟中性粒细胞（BANDS）增多，是急性细菌感染的征象。ABSOLUTE NEUTROPHIL COUNT是WBC乘以中性粒细胞加杆状核细胞的百分比；低于1,500为中性粒细胞减少，低于500为严重减少；中性粒细胞减少防护措施通常在低于约1,000时开始，具体按机构政策执行。PLATELETS：150,000到400,000/mm³；低于约50,000时开始采取出血防护措施，低于20,000时自发性出血风险升高。红细胞指数：MCV偏低提示缺铁；MCV偏高提示维生素B12或叶酸缺乏。ERYTHROPOIETIN用于治疗慢性肾脏病引起的贫血；铁剂应与维生素C一起服用，避开乳制品，且会使粪便变黑。

HEMOGLOBIN: men about 14 to 18 g/dL, women 12 to 16; HEMATOCRIT: men 42 to 52%, women 37 to 47%, roughly three times the hemoglobin. Low values mean anemia or bleeding; transfusion is often considered below 7 to 8 g/dL depending on symptoms and cardiac history. Hematocrit rises with dehydration and falls with fluid overload even when red cell mass is unchanged. WHITE BLOOD CELLS: 5,000 to 10,000/mm³; high counts suggest infection, inflammation, steroids or leukemia; low counts (leukopenia) follow chemotherapy, viral illness or marrow failure. A SHIFT TO THE LEFT means an increase in immature neutrophils (BANDS), a sign of acute bacterial infection. The ABSOLUTE NEUTROPHIL COUNT is the WBC multiplied by the percentage of neutrophils plus bands; below 1,500 is neutropenia and below 500 is severe; neutropenic precautions usually start below about 1,000, per facility policy. PLATELETS: 150,000 to 400,000/mm³; bleeding precautions begin below about 50,000, and spontaneous bleeding risk rises below 20,000. Red cell indices: a low MCV suggests iron deficiency; a high MCV suggests vitamin B12 or folate deficiency. ERYTHROPOIETIN is given for the anemia of chronic kidney disease; iron is taken with vitamin C, away from dairy, and it blackens stools.

🏥 真实场景

🔬 一名术后患者的血红蛋白在一夜之间从13.2降至8.9，心率为112。敷料上没有任何渗出。护士报告的是变化趋势，而不只是单个数字：下降4克发生在12小时内，在未证伪之前就意味着某处在出血。CT显示腹膜后血肿。实验室检查的变化趋势发现了敷料无法显示的问题。

🔬 A post-op client's hemoglobin falls from 13.2 to 8.9 overnight with a heart rate of 112. Nothing is on the dressing. The nurse reports the trend, not just the number: a 4-gram drop in 12 hours is bleeding somewhere until proven otherwise. The CT shows a retroperitoneal hematoma. The lab trend found what the dressing could not.

📌 要点总结

• 血红蛋白和血细胞比容都会随脱水而升高，随液体负荷过重或出血而降低Hemoglobin and hematocrit both rise with dehydration and fall with fluid overload or bleeding
• 核左移意味着杆状核细胞增多，意味着细菌感染Left shift means bands, means bacterial infection
• ANC低于1,500为中性粒细胞减少，低于500为严重减少；血小板低于50,000需要采取出血防护措施ANC under 1,500 is neutropenia, under 500 severe; platelets under 50,000 need bleeding precautions

✅ 自我测试