Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1052 page)

   Use

   Biomarker for body fat metabolism

   Interpretation

Increased In

   Obesity

   Pregnant women

Decreased In

   Fasting

   Very low–calorie diet

   Limitations

   Serum leptin concentrations increase with progressive obesity. The concentrations are higher in women than in men, for any measure of obesity, and they decrease with age in both women and men.

   Pregnant women have higher serum leptin concentrations than nonpregnant women.

   Serum leptin concentrations increase during childhood, with the highest concentrations in children who gain the most weight; higher serum leptin concentrations are associated with an earlier onset of puberty.

   The concentrations are similar in normal subjects and patients of the same weight with type 2 DM.

   There is a diurnal rhythm of serum leptin concentrations, the values being 20–40% higher in the middle of the night as compared with daytime. The peak shifts in parallel with shifts in the timing of meals.