Platelet count fall is an important part of the HIT score, as featured in Omni's 4T score calculator (HIT calculator). Here's the instruction on how to calculate it manually:
Analyze all the platelet counts that are available for a given period.
Find the greatest and the smallest value detected.
Use the equation:
Platelet count change(%) = (Smallest value × 100) / Greatest value
Yay! You got this. 
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