The Aspirin Episode of the Mystery of Platelet Disappearance

Author | Juman

| Anyang Cancer Hospital

Peripheral blood platelets diameter 2-4μm, average volume 7.
2fl, don't look at its small size, but the role is decisive, through adhesion, aggregation and secretion function to participate in the first-stage hemostatic process involving blood vessels and platelets, through its secretion of a variety of procoagulant factors, provide blood clotting catalytic surface and blood clot contraction, promote blood clotting ^[1].

Many tumor patients have thrombocytopenia during treatment, some are caused by bone marrow suppression, and some thrombocytopenia is unexplained, which requires us to carefully analyze and accumulate
.

Case history

The patient, a 69-year-old female, was admitted to the hospital with "postmenopausal intermittent vaginal bleeding for more than 3 months" and was clinically diagnosed with cervical squamous cell carcinoma stage
1b2.

On March 4, 2022, the patient received one cycle of chemotherapy with "sindilimab + paclitaxel + nidaplatin"; On March 17, radiotherapy began; On March 26, he received the second cycle of chemotherapy
.

On April 3, the patient's blood count was 1.
09×10 9/L, the percentage of neutrophils was 36.
6%, hemoglobin was 101g/L, and the platelet count was 113×10⁹/L
.
Leukocyte is markedly reduced, 3rd degree myelosuppression, granulocyte colony-stimulating factor whitening therapy
is used.

On April 5, the patient's blood count was 3.
25×10 9/L, the percentage of neutrophils was 49.
3%, hemoglobin was 91g/L, and the platelet count was 3×10⁹/L
.
The patient presents with severe myelosuppression and is infused with 2 platelets and thrombopoietin is used to stimulate platelet production
.

Blood routine results and clinical treatment measures for the next few days are shown in the table:

On April 6, the patient's platelet count had an unexplained decline and the platelet transfusion was ineffective, and the clinician questioned the results of the blood routine and asked us to retest on the one hand, and asked the nurse to replace the citrate anticoagulant tube on the
other hand.
We patiently communicate with the doctor, whether it is manual re-examination or replacement of blood collection tubes, it is for platelet aggregation; The patient's blood routine did not have an instrument alarm "platelet coagulation", and second, we prepared blood slides for microscopic review, platelets did not aggregate, and the number was consistent
with the instrument results.
The root of the problem is that the patient has a low platelet count, not that we can't find platelets
.

The patient transfused 6 platelets can not reverse the dilemma of thrombocytopenia, consistent platelet transfusion is ineffective, the reasons for the ineffectiveness of platelet transfusion are divided into two reasons, one is immune factors, seen in repeated platelet transfusion, pregnancy, serum production of PLT alloantibodies; The other is non-immune and is seen in DIC, fever, infection, sepsis, severe bleeding, splenomegaly, poor PLT storage, intravenous amphotericin B, etc
.
Doctors have ruled out the possibility
that platelet transfusion is ineffective based on the clinical manifestations of the patient.

Bewildered.
.
.
.
.
.

On April 9, the patient's platelets suddenly rose to normal, we asked the doctor why, the doctor said that the patient had been secretly taking aspirin, and after being discovered, the drug was stopped; After two days, the platelets returned to normal
.

In this case, the platelet count of the patient decreased, and the reason why multiple platelet transfusions were ineffective was the patient's private aspirin enteric-coated tablets
.

Aspirin enteric-coated tablets are antipyretic and analgesic, nonsteroidal anti-inflammatory drugs, and antiplatelet aggregation drugs
.
Low concentrations of aspirin can inactivate serine acetylation at the active center of PG synthetase, irreversibly inhibit platelet cyclooxygenase, reduce the production of thromboxane A2 in platelets, and affect platelet aggregation and antithrombosis, achieving the purpose of anticoagulation ^[2].

The original intention of patients taking aspirin is to prevent platelet aggregation, but there are side effects - thrombocytopenia, aspirin leads to thrombocytopenia mechanism: (1) immunosuppression, aspirin as a hapten drug, and platelets in plasma to form whole antigens, and then produce antiplatelet antibodies, the formed antigen-antibody complex attaches to the platelet membrane, resulting in platelets being phagocytosed by
the mononucleo-macrophage system 。 (2) The toxic side reaction of drugs to platelets, aspirin inhibits the synthesis of prostacyclin, makes platelet cyclopolymerase irreversible acetylation, thereby preventing platelet aggregation and shortening platelet life
.

Patients due to radiotherapy and chemotherapy lead to bone marrow suppression, platelet production decreases, the original platelets in the peripheral blood and transfused platelets due to the side effects of drugs, increased destruction, shortened life, these factors lead to a combination of platelet count continues to be low
.

References

[1] Liu Chengyu.
Fundamentals of clinical testing[J].
China Medical Science and Technology Press,2004:83.
)

[2] Yang Baofeng.
Pharmacology(7th Edition)[J].
People's Medical Publishing House,2008:184.
)