Variation in common laboratory test results caused by ambient temperature

Area of Science:

• Clinical Chemistry
• Laboratory Medicine
• Environmental Health

Background:

• Laboratory test results are crucial for physiological assessment but can be affected by external factors.
• Ambient temperature on the day of blood collection is an underappreciated source of variation in laboratory test results.

Purpose of the Study:

• To investigate the impact of ambient temperature on a wide range of laboratory test results.
• To determine if temperature-driven variations in test results influence medical decision-making.

Main Methods:

• Analysis of over 215 million laboratory test results from nearly 5 million individuals (2009-2015).
• Modeling test results as a function of daily temperature, controlling for individual and city-week fixed effects.

Main Results:

• Temperature significantly affected 51 out of 75 assays, including kidney function, blood cell counts, and lipid profiles.
• Cooler temperatures were associated with lower-risk lipid panels, leading to a 9.7% decrease in statin prescriptions compared to warmer days.
• Observed temperature-driven variations are unlikely to reflect stable physiological trends but do impact clinical decisions.

Conclusions:

• Ambient temperature is a significant factor causing variability in many laboratory tests.
• Temperature-induced distortions in test results can alter medical decision-making.
• Statistical adjustment for temperature in reporting is a feasible method to mitigate unwanted variability.