Example of specimens taken during a controlled fast
| Specimen | Test | Baseline sample | Postprandial sample | Samples at regular intervals | End of fast samples | Post end of fast samples |
|---|---|---|---|---|---|---|
| Blood | Bedside glucose (1 hourly) | ✓ | ✓ | ✓ | ✓ | ✓ |
| Lab glucose and lactate | ✓ | ✓ | ✓ | ✓ | ✓ | |
| Free fatty acids | ✓ | ✓ | ✓ | ✓ | ✓ | |
| 3-Hydroxybutyrate | ✓ | ✓ | ✓ | ✓ | ✓ | |
| Insulin | ✓ | |||||
| Growth hormone | ✓ | ✓ | ||||
| Cortisol | ✓ | ✓ | ||||
| Amino acids | ✓ | ✓ | ||||
| Liver function tests | ✓ | ✓ | ||||
| Ammonia and TCO2 | ✓ | ✓ | ||||
| Carnitine and acylcarnitine | ✓ | ✓ | ✓ | |||
| Urine | Amino acids and organic acids Collect aliquots of all urine passed from the beginning of the fast and the first and second urines after the end of the fast. Label carefully with the time and store separately in fridge so that the end of fast specimens can be identified and analysed. | |||||
Urine amino acids: helpful in diagnosing aminoacidopathies.
Postprandial samples: samples taken 1–2 hours postcommencement of the fast. These samples are physiological postprandial samples as the fast commences after the patient is given a meal.
Post end of fast samples: samples taken after termination of controlled fast.