犬猫贫血的实验室诊断

1、犬猫贫血的实验室诊断讲座二 贫血的实验室诊断 原著 Professor Michael J. Day 翻译：刘睿 兽医师（广州） ,校对：戴庶 兽医师（广州）、八虽然大部分的检测 在使用仪器检测 也包括血涂片检查前言 如果要对贫血动物做出成功的诊断和管理, 不可或缺一定水准的实验室检查。 血液学检查可 在院内做；或保存为 EDTA抗凝血后，送检至商业诊断实验室。要进行基本的血液分析，最 低限度的实验室设备应包括： 微量血细胞比容法离心机和毛细管判读器、 制备染色血涂片的 材料、用于评估血涂片所用的显微镜。准备一台折射仪来测定血浆蛋白含量也是有价值的。 如今,临床实验室已经有条件使用日趋精密的检

2、测设备来进行血液分析。 设备能够获得可信的红细胞和白细胞数据, 但血小板的检测值可能被低估。 血样的同时, 应配合血涂片镜检。 本讲座回顾了红细胞参数的相关知识, 中可能遇见的各种红细胞形态学改变情况。红细胞参数通过离心微量HcT）通过自或血细胞计红细胞计数，PCV和Hb 红细胞压积（PCV是指红细胞总数（RBCs所占全血中的体积比。PCV测量：红细胞压积管后，人工判读数据，并记录为占血液总量百分比。血细胞压积（ 动血液分析仪在细胞大小和数量的基础上判定。 红细胞总数可使用自动化仪器， 数器在镜下计数来获得，用RBC X 1012/1表示。血液中的血红蛋白（Hb）含量同样也可以使用自动化仪器判

3、定，记录为 g/dl。Hb （血红蛋 白）的含量测定受血液样本中存在脂血症、 红细胞溶解症或胆红素血的影响。 一个检验结果 精确性的简单方法：3 X Hb= Ht （血细胞压积）。检测到的数值要参照 “正常范围值” 来比较， 但要明确“正常范围值” 并不适用于所有情况。 举例来说，初生或者怀孕动物可能会呈现数值偏差，并且某些动物也存在品种效应（例如， 视觉猎犬（sight hounds）就呈现高PCV值和低嗜中性粒细胞计数）。PCV, RBC计数和HB都 反映了红细胞质量，并且这三个参数之间通常具有相关性，所以简单的测定PCV值即是一个良好的临床指征。中度贫血 18-29%，重度贫血 18%。

4、 中度贫血 15-19%，重度贫血 60 X 109/表示显著的再生。RPD也可能需要确定。RPI对“校正”贫血程度集结状网织红细胞，但猫二者都有。在犬上， 网织红细胞百分比 （在红细胞中） X 109/l 是再生性贫血反应的象征， 400 作为另外一个选择，网织红细胞生成指数（ 的评估和网织红细胞寿命有重要价值。1 ）贫血程度校正校正值% （或计数值）=绝对值% （或计数值）X PCV值/正常PCV值（45） 2）网织红细胞寿命校正RPI = 校正值 % X 1/血液成熟时间 血液成熟时间取决于 PCV值：PCV45%1 天35%1.5 天25%2 天15%2.5 天RPI 2.5时，表示再

5、生性贫血反应。猫集结状网织红细胞最初从骨髓中被释放， 在经过 10-12 天的成熟期后， 转变为点状网织红 细胞。 相比之下，点状网织红细胞在循环血液中出现需要 3-4 周。在猫上，集结状网织红 细胞计数可判定再生性贫血， 它反映骨髓再生活跃程度， 而点状红细胞计数代表累积再生贫 血。集结状红细胞计数 40 X 109/l 表示再生性贫血， 200 X 109/l 时表示显著再生性贫血。而后一种样本给 但要获得优质的穿 通常在股骨干骨髓评估 对于非再生性贫血的病例，骨髓评估是诊断过程的一个重要步骤。可能需要采集两种样本： 抽取骨髓内容物或用骨髓针穿刺活检。 前一种样本给临床病理学专家分析， 组

6、织病理学专家分析。 骨髓穿刺针的优点是病理组织可得到更好的评估， 刺活检物却具有挑战性。 将穿刺活检物放入福尔马林溶液固定之前先做压片。骨（猫）或髂骨嵴（犬）来获得样本。在大型犬，肋骨或胸骨节是骨髓抽取的备用位置。抽取的骨髓样本应放入 EDTA或ACD （可从采血袋中获得）抗凝血剂中保存，同时至少要制备 10 张压片， 迅速空气干燥后染色。 主要的谱系细胞应该按照成熟程度、 所占的相对比例、 粒细胞和红细胞比例的顺序依次确定。同时应该检测异常细胞（肿瘤细胞）LECTURE 2. LABORATORY DIAGNOSIS OF ANAEMIAINTRODUCTIONThe anaemic pat

7、ient cannot be successfully diagnosed and managed without at least some level of laboratory testing. This may be undertaken in-practice or by sending EDTA anticoagulated blood to a commercial diagnostic laboratory. The minimum in-practice equipment required for basic haematological analysis would be

8、 a microhaematocrit centrifuge and tube reader, materials for preparation of a stained blood smear and a microscope for evaluation of the blood smear. A refractometer for assessment of plasma proteins is also valuable.Increasingly sophisticated instrumentation is now available for in-practice labora

9、tories to undertake haematological analysis. Most of these machines produce acceptable data for red and white blood cells but may underestimate platelets. It is essential to examine a blood smear in parallel with assessing the readings from such equipment. This lecture reviews the erythrocyte parame

10、ters and cytological changes that may be seen on examination of the blood smear.ERYTHROCYTE PARAMETERSTotal red blood cell count, PCV and HbThe packed cell volume (PCV) is the percentage of blood volume made up of red blood cells (RBCs). It is determined manually by centrifugation of a microhaematoc

11、rit tube and recorded as a percentage of blood volume. The haematocrit (Hct) is determined by the automated haematology analyser on the basis of cell size and number. The total RBC count is determined in automated fashion or may be measured manually using a haemocytometer chamber and microscope. Thi

12、s parameter is recorded as RBC X 101/2l. The concentration of haemoglobin (Hb) in the blood is also determined in automated fashion and reported as g/dl. Determination of Hb concentration will be affected by the presence of lipaemia, haemolysis or bilirubin in the blood sample. A simple check for ac

13、curacy is that the HbX 3 should equal the haematocrit.These values are assessed relative to a normal reference range but it should be remembered that these reference ranges may not apply to all situations. For example very young animals or pregnant animals may have outlying values and there are some

14、 breed-related effects (e.g. sight hounds have relatively high PCV and lower neutrophil count). The PCV, RBC count and Hb all reflect the red cell mass and these three parameters generally correlate, so simple PCV measurement is a good index to use.The PCV may be used to describe the severity of ana

15、emia. As an approximation a doghas a mild an aemia with a PCV of 30 -36%, moderate an aemia at 18 -29% and severe an aemia at 18%. A cat has mild anaemia at 20 - 24%, moderate anaemia at 15 - 19% and severe anaemia at 60 a count of 400 X109/l indicates markedproduction index (RPI) may be determined.

16、 anaemia and the lifespan of the reticulocyte. is calculated by:Corrected % (or count) = observed % (or count) The second correction is for reticulocyte lifespan:In the dog the percentage reticulocytes (of red cells) should be expressed as an absolute X109/l is indicative of a regenerative response

17、and regeneration. Alternatively, the reticulocyte The RPI correctsthecount for the degree of The first correction is for degree of anaemia thatX observed PCV/normal PCV (45)45%1 day35%1.5 days25%2 days15%2.5 daysRPI = corrected % /bloxod 1maturation time where maturation time depends upon the PCV: P

18、CVAn RPI 2.5 indicates a regenerative anaemia.Feline aggregate reticulocytes are recent marrow emigrants that become punctate reticulocytes after a 10 -12 day maturation time. By contrast, punctate reticulocytes have been present in the circulation for 3 - 4 weeks. Aggregate reticulocytes should be

19、counted to determine regeneration in the cat as they represent active bone marrow regeneration whereas pun ctate forms rep rese nt cumulative rege nerati on.An aggregate count of 40x 109/1 in dicatesrege nerati on and of 200x 109/l in dicates marked rege nerati on.BONE MARROW EVALUATIONFor non-regen

20、erative anaemia evaluation of the bone marrow is an important part of the diagnostic process. Two sample types may be collected: an aspirate of medullary content or a bone marrow needle core biopsy. The former sample is evaluated by the clinical pathologist and the latter by a histopathologist.The advantage of core biopsy is that the tissue pathologymay be better evaluated, but