Use

Serum or plasma caffeine levels are clinically significant for evaluating exposure to caffeine—whether through beverages like coffee or tea, over‑the‑counter or prescription products—and are especially important in neonates. In premature infants treated with theophylline or caffeine for respiratory distress, theophylline metabolizes to caffeine, and caffeine clearance pathways may be underdeveloped, resulting in elevated levels. Caffeine levels in infants typically reach adult clearance values by approximately 3–4 months of age.