Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Caffeine is used to treat apnea that occurs in newborn infants, the most frequent complication seen in the neonatal nursery.
Caffeine is administered orally (nasogastric tube) as a loading dose of 3 mg/kg followed by a maintenance dose of 1 mg/kg administered once every 24 to 48 hours, depending on the patient's response and the serum level.
In neonates, caffeine has a half-life that ranges from 20 to 100 hours, which is much longer than in adults (typically 4-6 hours) due to the immaturity of the neonatal liver. This requires that small doses be administered at much longer intervals than would be predicted based on adult pharmacokinetics.
The volume of distribution of caffeine is 0.6 L/kg and the drug is approximately 35% protein bound.
Toxicity observed in neonates is characterized by central nervous system and skeletal muscle stimulation and bradycardia. These symptoms are seen in adults at lower levels than in neonates, suggesting that neonates have much greater tolerance to the drug.
Monitoring therapy in neonates
Assessing toxicity in neonates
Optimal pharmacologic response occurs when the serum level is in the range of 5 mcg/mL to 15 mcg/mL.
Toxicity in neonates and adults may be seen when the serum level is > or =20 mcg/mL.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
This assay is not intended to detect levels in adults.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Therapeutic concentration: 5-15 mcg/mL
Toxic concentration: > or =30 mcg/mL
Clinical References Provides recommendations for further in-depth reading of a clinical nature
Ou CN, Frawley VL: Concurrent measurement of theophylline and caffeine in neonates by an interference-free liquid-chromatographic method. Clin Chem 1983;29:1934-1936