How long should you fast for a fasting metabolic panel? I keep hearing varying numbers. I'm assuming drinking water is ok at any point in time.

Prior . Prior to answering your question, avvo's terms of use state, "such information should be used only as a starting point for addressing your medical issues. It is not a substitute for medical advice, diagnosis or treatment. You should not disregard medical advice from your doctor, or avoid obtaining medical care, due to any health information you obtain on the site." in general, fasting is greater than 8 hours, however most achieve at least 12 hours since labs are drawn at 8am and the patients meal (dinner) was the prior night at 8pm. This is done in order to get accurate lab tests and imaging. Water usually doesn't interfere with the lab tests however drinking too much or too little can alter your creatinine (kidney function), so would discuss with your physician if they are specifically looking at this number and want you to fast for a specific time.