Why order a CBC to workup a headache?

[Waysensei]

I'm reading through FA for Step 2 CS and for a headache, it often lists a CBC as the first step in the workup. I'm wondering why this is and what information it adds. The only thing I can think of is that it may help to r/o infection and polycythemia which may produce clots?

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[kemper6036]

i can't think of a great reason, but how many pt have you had who get a cbc, bmp, cxr etc for no good reason?

its defensive medicine and in the case of CS, just something to fill in the space on your note

 

[yaah]

Things associated with headaches that can be seen on CBC: Anemia, polycythemia, thrombocytopenia (with resulting bleed), thrombocytosis, leukocytosis (neoplastic or reactive), leukemia (chronic or acute).

 

[radiodoc99]

You have to rule out Temporal arteritis which has increased erythrocyte sedimentation rate (ESR) > 60 mm/hour, mild leukocytosis, mild normochromic normocytic anemia, thrombocytosis and occasionally (20-30%) liver function test abnormalities (usually increased alkaline phosphatase). For migraines, tension headaches there is no need for a CBC, but it would help.