Platelet Count (Blood)

Testing Laboratory

Department

Haematology

Delphic Registration Code (Alpha Code)

FBC

Test Code (Numeric Code)

1000

Laboratory Handling

Sample Stability

FBC analysis should occur within 6 hours of collection but may be processed up to 24 hours post collection if the sample is refrigerated at 4 degrees C.

Associated Tests

• Full Blood Count (Blood)

Synonyms

Thrombocyte Count, Blood Platelet Count

Turnaround Time

1 hour

Available 24 hours

Specimen Type

• Whole Blood

Specimen Requirements

Tube/Container Type:

Preferred

• Please refer to Additional Information below
• EDTA (Lavender Cap)

Preferred Sample Volume (ml)

3

Paediatric Specimen Requirements

Tube/Container Type:

Preferred

• EDTA (Microtainer)
• Please refer to Additional Information below

Preferred Sample Volume (ml)

0.5

Additional Specimen Information

In patients where EDTA mediated platelet clumping has been reported, an accurate count can be obtained by collecting a Citrate tube (blue top) - Tube must be filled up to the "Fill Line"

Uncertainty of Measurement

12%

Platelet Function:

Normally, platelets do not adhere to blood vessel walls because the endothelial cells produce prostaglandin I2and nitrous oxide. Both of these substances are vasodilators and inhibit platelet aggregation. If the vessel is injured, the platelets will adhere to exposed collagen and microfibrils via glycoprotein receptor sites on the platelet membrane. Following adhesion, the platelets become more spherical, start putting out long psedopods and their cytoplasmic granules are forced towards the cell membrane. These granules produce many platelet aggregating agents, such as thromboxane A2, thus activating more circulating platelets. Platelet aggregation, as well as binding to fibrinogen, leads to the formation of the platelet plug. This, coupled with local vessel vasoconstriction, is usually sufficient to maintain haemostasis, but in larger vessels fibrin is also necessary to prevent the plug from being dislodged

Contact Information