Recent Blog Articles
Monkeypox: An unfamiliar virus spreading fast — sound familiar?
Diabetes: Does a long-term study reinforce or change approaches to prevention?
War anxiety: How to cope
Can we prevent depression in older adults by treating insomnia?
Want to try veganism? Here's how to get started
Vitamin B6 flies under the radar: Are you getting enough?
The formula shortage is hurting families: What parents should know and do
Gyn Care 101: What to know about seeing a gynecologist
Swimming lessons save lives: What parents should know
Strong legs help power summer activities: Hiking, biking, swimming, and more
Staying Healthy
Ask the doctor: What blood tests require fasting?
Q. Sometimes my doctor tells me it's okay to eat before a blood test, and sometimes it isn't. Why is that?
A. Actually, fasting affects the results of very few blood tests. For example, measurements of kidney, liver, and thyroid function, as well as blood counts, are not influenced by fasting. However, fasting is required before commonly ordered tests for glucose (blood sugar) and triglycerides (part of the cholesterol, or lipid, panel) for accurate results.
To continue reading this article, you must log in.
Subscribe to Harvard Health Online for immediate access to health news and information from Harvard Medical School.
- Research health conditions
- Check your symptoms
- Prepare for a doctor's visit or test
- Find the best treatments and procedures for you
- Explore options for better nutrition and exercise
I'd like to receive access to Harvard Health Online for only $4.99 a month.
Sign Me UpAlready a member? Login ».
Disclaimer:
As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles.
No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.
You might also be interested in…
Living Better, Living Longer
With this Special Health Report, Living Better, Living Longer, you will learn the protective steps doctors recommend for keeping your mind and body fit for an active and rewarding life. You’ll get tips for diet and exercise, preventive screenings, reducing the risk of coronary disease, strengthening bones, lessening joint aches, and assuring that your sight, hearing, and memory all stay sharp. Plus, you’ll get authoritative guidance to help you stretch your health care dollar, select a health plan that meets your needs, prepare a health care proxy, and more.
Free Healthbeat Signup
Get the latest in health news delivered to your inbox!
