Excel Question

I am hoping to come up with a formula, which I have been trying to figure out for some time now.

I have Column A which contains a list of thyroid values. I want to come up with a way of having 3 cells in Column B SUM the patients from Column A based on IF criteria.

A3:A350 – thyroid values
C4 – # of patients hypothyroid (with thyroid values <1.9) C5 - # of patients euthyroid (with thyroid values >1.9 <4.0 ) C6 - # of patients hyperthyroid (with thyroid values >4.0)

I am hoping someone out there might be able to help me create a formula for this situation.

Kind Regards and Thanks in Advanced,

Daniel