Morning Serum Cortisol Test

A highly sensitive quantitative biochemical assay measuring the basal level of Cortisol, a primary glucocorticoid hormone, in blood serum. The biological sample is strictly extracted in the early morning, characteristically between 7:00 AM and 9:00 AM, to align with the hormone's natural physiological fluctuations. Cortisol secretion is tightly regulated by a distinct circadian rhythm; it achieves its peak concentration in the early morning hours upon waking, and subsequently undergoes a gradual decline throughout the daylight hours, culminating at its physiological nadir near midnight. The early morning baseline measurement provides the most diagnostically relevant and accurate representation of adrenal cortex functionality, playing a vital role in identifying hypercortisolism (e.g., Cushing's syndrome) or hypocortisolism (e.g., Addison's disease).