lnBHB

lnBHB is the natural logarithm of the concentration of beta-hydroxybutyrate (BHB), a ketone body produced during fatty acid oxidation in the liver. In biomedical research and biostatistics, lnBHB refers to the transformed value obtained by taking the natural log of measured BHB concentrations, which are typically reported in millimoles per liter (mmol/L). The log transformation is commonly used to normalize skewed distributions, stabilize variance, and improve the performance of statistical models.

Calculation and data considerations: If a BHB measurement is x mmol/L, then lnBHB = ln(x). Since the natural logarithm requires positive inputs, zero or negative values are undefined. In practice, researchers may add a small constant to all observations or use alternative transformations to handle zeros, depending on the study design and analysis plan. The transformation is unitless, but the underlying BHB units influence the interpretation of results through back-transformation.

Usage and interpretation: lnBHB can be employed as a dependent variable to assess factors associated with changes in ketone levels, or as an independent variable to study its relationship with clinical or metabolic outcomes. A one-unit increase in lnBHB corresponds to a multiplicative increase in BHB by a factor of e (approximately 2.718). For example, a rise from BHB to about 2.72 times that amount yields an increase of one in lnBHB; a doubling of BHB corresponds to an increase of approximately 0.693 in lnBHB.

Limitations: The transformation affects interpretability in clinical terms and requires consistent units and appropriate handling of zero values.