fasting before a blood test

Hi, I am having a blood test tomorrow morning.  My doctor told me I need to fast for 12 hours ahead of time.  But I can't remember if drinking fluids is okay - like water or herbal tea.    Please respond before I die of thirst!

Is it possible to call your doctor? What's the test for? Usually for testing for cholesterol levels water is fine - the tea *should* be fine but  I can't guarantee it.

Test is for

Biochemistry:  glucose, TSH, creatinine, sodium, potassium, chloride, CK, ALT, alk. phosphatase, Lipid assessment (including cholesterol, HDL-C, trigycerides) ferritin, albumin/creatinine ratio, urine

and

Hematology: CBC

Yeah... maybe I'll try to find my doctor's office after-hours phone number.

But wouldn't water affect the sodium levels? I'm no expert, but was under the impression it would.

I would imagine water is OK though as long as it's not in excess.

I am a soon to be nurse. Just looked up in my book of lab and diagnostic tests, and it says you should fast from food and fluid, esp for creatinine and cholesterol (which to be honest i thought water would be ok)... call your md to double check

Hi,

I used to be a practice nurse (working in a GP's surgery doing blood tests etc) and for fasting bloods, you could have water but nothing else. Obviously, drinking 4 litres of water would affect the results, but just a glass of water should be fine. The fasting aspect relates to the glucose, and sometimes the lipids depending on what they are looking for. I have never ever been asked to do a fasting sodium level.

Good luck!

I was told not to drink any water.