Study Reveals Most Tests Don’t Require Extended Fasting

According to a recent observational study, fasting for less than 8 hours before standard blood tests typically does not alter the results, with only a few exceptions.

In analyses involving over 100,000 patients who underwent multiple blood collections, the vast majority of the 372 test items did not exceed established analytical performance specifications with less than 8 hours of fasting, as reported by Dr. Sollip Kim and colleagues from the University of Ulsan College of Medicine in Seoul, Korea, in JAMA Internal Medicine.

However, it was noted that for specific tests, the differences were more pronounced when comparing fasting durations:

• Glucose: +13.0 mg/dL (compared to <8 hours fasting) and +10.8 mg/dL (compared to 8-12 hours)
• Triglycerides: +17.1 mg/dL and +20.1 mg/dL
• Gamma-glutamyl transferase: +21.7 U/L and +14.8 U/L
• Lipase: no comparison available against 8-12 hours, but +36.4 U/L when compared to >12 hours

The researchers stated, “This cross-sectional study found that the duration of fasting was associated with differences exceeding analytical performance specifications for only a few analytes.” They emphasized that fasting requirements should be analyte-specific rather than uniform.

Fasting, defined as the intentional wait between the last meal and blood collection, has traditionally been a practice aimed at standardizing preanalytical variations in laboratory results.

In this study, participants who fasted for less than 8 hours exhibited a linear trend indicating that glucose and lactate levels decreased significantly for each additional hour of fasting. Conversely, the findings for lipid results did not improve with extended fasting hours.

Clinicians should consider careful interpretation for a limited number of postprandial-sensitive analytes when results are obtained from very short fasting periods.

In managing and diagnosing diabetes, reliance has already shifted to HbA1c, which measures blood sugar over the past 2-3 months, showing less day-to-day variability. Nonetheless, fasting plasma glucose remains an essential test for diabetes, particularly where HbA1c may not be reliable.

Concerning cholesterol screenings, U.S. guidelines advocate for either fasting or non-fasting lipid profiles for adults and children; however, a fasting lipid profile is preferred for assessing LDL cholesterol in individuals with a family history of dyslipidemia or premature heart disease, suspected triglyceride metabolism disorders, or non-fasting triglyceride levels exceeding 400 mg/dL.

In an accompanying editorial, Børge Grønne Nordestgaard and colleagues from Copenhagen University Hospital highlighted that this study supports the growing evidence suggesting fasting blood sampling is often unnecessary.

The editorial stressed that the understanding that fasting offers little to no added benefit in interpreting most laboratory test results represents an important message for laboratories, clinicians, and patients. It is anticipated that eliminating the fasting requirement could enhance patient compliance and satisfaction with healthcare services.

This retrospective study included adult outpatients with recorded fasting durations, gathering data from 9,755,547 test results across 101,148 patients, with a median age of 61 years and 43% being women.

It’s important to note that this study has limitations, including its focus on a single center’s outpatient phlebotomy unit and the absence of adjustments for macronutrient composition in pre-testing meals. Additionally, the applicability of the results to younger demographics remains uncertain.

While the findings were derived from a primarily East Asian cohort, the authors believe that the results are generally relevant to various ethnicities and countries.

Disclaimer: Always consult with a healthcare professional for advice regarding medical conditions or treatments.

Fuente: https://www.medpagetoday.com/primarycare/preventivecare/123173