Calculations of osmolarity/osmolality

[nickfrancis]

Hi all

I have my data interp exam later, and they always seems to ask us questions on various ways to calculate the osmolarity/osmolality of a solution, and drug dose calculations. I haven't done this since GCSE (about 10 years ago) and I can't find any decent explanations on the internet that are really relevant.

Anyone want to have a quick go at teaching?!

Cheers

Nick

[Spencer Wells]

The only osmolality calculation that I do with any frequency (as it's always examined) is plasma osmolality, which is actually pretty simple.
In real life you just send other fluids (urine, for example) to biochemistry and get them to report the value for you.

plasma osmolality:

2(Na + K) + glucose + urea