Table 2.

Comparison of the invasive and non-invasive methods for detecting cortisol.

Items	Noninvasive	Invasive
Sample	Saliva, hair, and urine	Blood (plasma, serum) and CSF
Sampling methods	Swabs for saliva, hair near the scalp, and 24-h urine collection in a container	Peripheral blood collection and lumbar puncture
Clinical usage	Occasionally performed for endocrine disease	Blood samples are frequently obtained for endocrine disease, stress dysregulation, and infertility
Diagnostic method	ELISA for saliva and urine and LC-MS for hair	Chemiluminescence, ELISA, and lateral flow assay
Sampling conditions	Hospital or home, single or multiple time points, and variations in sample matrix and storage	Hospital, usually single time point per day, standard operation, consumables, and storage
Sample preparation	Easy for saliva, very complicated for hair	Easy and standardized
Detection time	Commonly 4–24 h for ELISA and >24 h for LC-MS	Commonly 1–2 h for chemiluminescence, 4–24 h for ELISA, and 10–15 min for lateral flow assay
Source of error	Self-sampling, storage, transportation, sample preparation, experimental operation, and quality of test kit	Calibration of equipment, experimental operation, and quality of test kit

CSF, cerebrospinal fluid; ELISA, enzyme-linked immunosorbent assay; LC-MS, liquid chromatography mass spectrometry.