The patient had 24 blood routine tests, but the latter two had abnormally high platelets

foreword

Platelets are an important parameter in blood routine tests, and many factors can interfere with platelet coun.

case after

On March 29, 2022, when reviewing the results, the blood routine test results in Figure 1 were encountered, and the test results were consistent with the historical resul.

figure 1

Preliminary judgment, the possibility of falsely elevated platelets, check the platelet histogram, see Figure

figure 2

The right side of the platelet histogram floats high, and the high boundary line reaches 30.

image 3

The platelet result for the optical channel was 1400×10^9/L, which was significantly lower than the result for the electrical impedance chann.

Figure 4

Looking at the platelet histogram on March 1, the histogram is similar to the results of this test, and the high boundary line is 31.

The patient is a 16-year-old female patient who was diagnosed with thalassemia for more than 10 years and was admitted to the hospital with 3 days of fatig.

Figure 5

The results of the last two platelet tests were significantly higher, and there was no significant difference in the platelet histograms of the previous blood routine tests of the patie.

Image 6

case analysis

By looking at the platelet histogram high mark, see Figure 7, we find the reason for the last two falsely high platele.

Figure 7

The department where the author works has two different types of blood routine analyzers, and there are 17 samples with high landmarks seen from Lis (green vertical lines in F.

Floating landmark is the platelet count method of Sysmex blood analyzer [

When the instrument encounters an abnormal PLT histogram, its high boundary line will drift, that is, it may not be able to locate the same position every time, resulting in deviations in the PLT resul.

Summary

How should laboratory staff identify these false elevations of platelets?

Step 1: Check the following items that are closely related to the false elevation of platelets: MCV↓, indicating that the blood picture is microcytic anemia; RDW-CV is high, RDW-SD result has not been obtained, indicating that the patient's red blood cell size is severely uneven , erythrocyte debris or microcytes may be prese.

Step 2: Check the platelet histogram, if the histogram is normal, the possibility of falsely high platelets in the sample is low; if the histogram is abnormal but the platelet high boundary line does not move to the right (less than 15fl), the sample platelets may be slightly high On the contrary, the high threshold line is obviously shifted to the right by more than (15fl), and the degree of high platelet in the sample is proportional to the high threshold li.

Normal platelets are usually distributed in the range of 2 ~ 30fl, mainly concentrated in 2 ~ 15fl, showing a unimodal curve with a skewed distributi.

In clinical work, especially in Guangdong and Guangxi, there are many samples that violate this ru.

[references]

[1] Tong Ru, Li Zhuo.

[2] Cheng Can, Quan Hongji.

Discussion on the re-examination rules of Beckman LH750 blood smear in ISO15189 accredited laboratory [.

Chinese Journal of Modern Medicine, 2013, 23(34): 53-5