how do there know u got leukemia?

i had 2 have the Blood test but with out that How did there no i had it
i passed out and then i went 2 the hosptail and then i got a blood test and found Leukemia
I took my daughter to the doctor cause she was very pale with black rings around her eyes. She looked so sick, but I never thought for a moment she had leukaemia. They did a blood test and a bone marrow biopsy and found she had cancer.

I guess the hospital did a blood test to see why you passed out, you cant tell from looking at someone they have leukaemia.

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