Does fasting mean you can't even drink water?

The situation of fasting is mainly a check and precaution that needs to be taken during the experience, which is a guarantee for the test results. Fasting means not being able to eat food, not not being able to drink water. Please don’t misunderstand. Not drinking water will lead to increased blood concentration and dehydrated skin. Therefore, for various examinations, you need to fast. You still need to consult your doctor for advice.

Which tests require fasting?

Gastroenteroscopy, abdominal ultrasound, blood tests, etc.

Fasting is mainly aimed at some specific items that are easily affected by eating, such as: gastrointestinal endoscopy, abdominal ultrasound, blood sugar, blood lipids, certain specific biochemical metabolic indicators and other examinations.

Gastrointestinal endoscopy

If fasting is not performed, a large amount of food residue will seriously affect the observation of the gastrointestinal mucosa and increase the risk of vomiting aspiration or choking.

Abdominal ultrasound

Ultrasound examinations rely on real-time feedback.

After eating, the various organs of the human digestive system begin to become active, the gallbladder contracts, bile is secreted, gastrointestinal motility accelerates, and the gas and fluid in the gastrointestinal tract increase, which will seriously interfere with the ultrasound physician's observation of the various digestive system organs.

Kind tips

If you are examining your urinary system, your doctor may ask you to hold your urine.

Blood test

Blood sugar, blood lipids and certain biochemical metabolic indicators are greatly affected by eating. After eating, food is quickly broken down into small molecules and enters the blood, affecting various indicators.

The purpose of fasting blood test is to make comparison under unified "standards", which is clinically meaningful.

Kind tips

These indicators are often given a reference range. If you don't understand, please go to the outpatient clinic to ask the doctor. It is not recommended to measure them on your own, which will scare you to death, make you lose your appetite, and affect your sleep...

What is considered fasting?

Fasting requires overnight stay

The fasting mentioned in the physical examination is not simply "going hungry for a meal". The fasting standard is 8-14 hours (overnight) without calorie intake.

That is, the night before the blood test, you should eat dinner normally according to your usual lifestyle, but not have a midnight snack. Do not eat breakfast the next morning for the test.

Therefore, it is necessary to grasp the reasonable fasting time. The best time for fasting blood collection is from 8 to 9 in the morning, and it is best not to exceed 9:30.

If it is too late, it will be affected by physiological and endocrine hormones.

For example, blood sugar will further decrease as the fasting time increases. If blood sugar decreases due to starvation for too long, it will not only affect judgment but may also lead to the risk of hypoglycemia.

Can I drink water?

Specific analysis of specific issues

For some tests, you can drink a small amount of water as long as it does not affect the results.

Fasting blood sampling does not require absolute abstinence from water. Many friends often abstain from water for more than ten hours because of the saying "can't eat or drink". In fact, some people are already in a state of dehydration, which leads to obvious bias in the test results.

If you feel thirsty, drink a small amount of boiled water until the thirsty feeling disappears. (Not including beverages, tea, wine, soda...)

For patients with hypertension, can they take an antihypertensive pill orally in the morning before a gastrointestinal endoscopy? There is absolutely no problem with that! Do they have to "take it dry"? There is absolutely no problem with drinking a sip of water.

If you are only having a colonoscopy without anesthesia, it is okay to drink a small amount of water.

It is not advisable to drink a lot of water before an abdominal ultrasound examination, but drinking just a sip of water actually has little impact. However, if you secretly eat an egg, that won’t work, because solid, caloric food will activate our digestive system.

What other dietary precautions should be taken before the physical examination?

Eating too much oil can cause inaccurate liver function results

If you eat a lot of high-fat food the day before the physical examination, triglycerides will increase significantly. Some people's blood may even become milky and look turbid, which will affect the accuracy of many tests such as liver function.

suggestion

Avoid greasy food 3 days before the physical examination.

In addition, eating large amounts of high-protein foods can increase the levels of urea nitrogen and blood creatinine, creating the illusion that there is a problem with kidney function.

It is recommended to maintain normal eating and living habits two weeks before the physical examination.

Eating the wrong food can cause a "false positive".

Fecal occult blood testing is the most widely used and evaluated method for colorectal cancer screening.

Sometimes, some foods you eat or unintentional behaviors may cause the result to be a "false positive".

For example, if you ate spinach, animal blood products, pork liver, etc. one or two days before the test, or brushed your teeth too hard and had frequent gum bleeding, even if you accidentally swallowed a small amount, it will affect the test results.

In addition, if people with hemorrhoids strain too hard when using the toilet, the result may also be positive.

suggestion

One or two days before having a stool test, avoid eating spinach and pork liver, and don't eat too much spicy food.

Drinking too much alcohol affects the electrocardiogram

Drinking alcohol can affect the results of some blood tests, the most common of which are triglycerides, transaminases, and uric acid.

Large amounts of alcohol can also cause changes in blood pressure, increase heart rate, induce arrhythmia, and reduce the accuracy of electrocardiograms and cerebral blood flow graphs.

suggestion

It is best not to drink a lot of alcohol 3 days before the physical examination, and definitely not to drink alcohol the day before the examination.