Medical study questions necessity of fasting for routine blood tests

A study published in JAMA Internal Medicine suggests that mandatory fasting may be unnecessary for most routine blood tests. The research analyzed over 9.7 million results across 121 types of tests from more than 101,000 patients.

Findings indicated that complete blood counts, renal function markers, electrolytes, and most liver enzymes showed little to no significant change based on fasting duration. The study compared patients fasting for less than eight hours, between eight and 12 hours, and more than 12 hours, noting that extending fasting beyond 12 hours provided no additional relevant benefits.

However, certain tests were affected by shorter fasting periods. Specifically, fasting for less than eight hours was associated with glucose levels being 10.8% higher, triglycerides 20.1% higher, and lipase 36.4% higher. For every additional hour of fasting, glucose levels decreased by approximately 4.3 mg/L. The researchers suggest these results challenge the necessity of strict fasting requirements for all laboratory examinations.