Only the amount of medical expenses over the 10% gets used as an itemized deduction. But, you still need to be able to itemize your deductions in order to benefit - i.e you need to have more total itemized deductions than the standard deduction.
For 2016, the standard deduction amounts are: $6,300 (single), $12600 (married filing jointly), or $9,300 (head of household). Every taxpayer starts off with these amounts in deductions as a "base" deduction from income that the IRS allows. So, you will need to have total itemized deductions (things like medical expenses, mortgage interest, property taxes, charitable donations) greater than these amounts before you start to see additional tax benefit from itemizing your deductions.
Example: Your AGI is $40,000, you are single and you have $5,000 in medical expenses - this gives you a medical expense deduction of $1,000 after the 10% threshold. So, you would still need to have $5,301 in other itemized deductions before you start to see greater tax benefits as the $1,000 medical expense is still below the $6,300 standard deduction.
Also, these are only deductions from income - they will not directly add the amounts into your refund.
Example: Your AGI is $40,000 and you have a $10,000 itemized deduction for medical expenses after the 10%. You don't receive this $10,000 back as a refund, it reduces the amount of income you pay tax on. So, now instead of paying tax on $40,000, you only have to pay tax on $30,000.
Also, the student loan interest paid deduction is a bit different. While it is still only a deduction from income, that deduction is called an "above the line" deduction, which means you get to take that deduction before you apply either the standard deduction or itemized deductions. So, it is not subject to the same rules as above.
