Scientists Identify Which Blood Tests Need to Be Taken on an Empty Stomach
Amul Info ·
A study published in JAMA Internal Medicine analyzed laboratory results from more than 101,000 patients. Researchers found that eating can particularly affect blood glucose, triglycerides, lipase, and GGT levels. Prolonged fasting may also influence bilirubin and certain vitamin D measurements.
Fasting before blood tests has been a common requirement in medical practice for many years. However, the findings of a new scientific study indicate that avoiding food is not essential for every blood test. According to the researchers, fasting can have a significant effect primarily on the results of four types of laboratory tests.
The study, published in the scientific journal JAMA Internal Medicine , analysed extensive laboratory testing data from a hospital in South Korea. Scientists examined approximately 10 million laboratory results from 101,148 patients aged between 18 and 106. Participants were divided into three groups according to the time elapsed since their last meal: less than eight hours, 8–12 hours, and more than 12 hours.
According to the findings, of the 121 indicators examined, food intake or fasting had a particularly significant effect on only four. These were blood glucose, triglycerides, the enzyme lipase, and gamma-glutamyl transferase (GGT).
Glucose helps determine blood sugar levels. Triglycerides are a type of fat stored in the body as an energy reserve. Lipase is an enzyme produced by the pancreas that helps digest fats. GGT is an enzyme indicator used primarily to assess the condition of the liver and bile ducts.
The scientists also found that levels of total bilirubin and 25-hydroxyvitamin D, the main metabolite of vitamin D, could change after more than 12 hours of fasting. Therefore, prolonged abstinence from food may also affect the results of these tests. For most other tests, however, extending the fasting period beyond 12 hours did not substantially alter the results.
The study also identified differences in whole-blood glucose, CA-125, a marker used in the assessment of ovarian diseases, including ovarian cancer, and total carbon dioxide, which is associated with the body's acid-base balance. Changes were also observed in low-density lipoprotein (LDL) levels. However, this indicator is calculated using other measurements, meaning that several factors may affect its results.
The study's authors also acknowledged several limitations. In particular, the data came from a single hospital in South Korea, and most participants were older adults. Therefore, additional research may be needed before the findings can be applied equally to the entire population.
Is fasting always necessary before a blood test?
Although the findings suggest that fasting is not mandatory for many blood tests, patients should not disregard this requirement on their own. A doctor may recommend fasting before certain tests, while in some cases, avoiding food is necessary when several tests are performed at the same time.
Therefore, it is important to follow the instructions provided by a doctor or laboratory before having blood drawn. In particular, people with diabetes should consult their doctor before going without food for an extended period. Proper preparation for testing helps ensure accurate results and an appropriate assessment of a person's health.