====== Serum cortisol ======
✔ 8 A.M. cortisol & 24-hour urine free cortisol ([[Cortisol urine test]])

Serum [[cortisol]] measurements are primarily used to diagnose states of cortisol excess ([[hypercortisolism]]) or deficiency ([[hypocortisolism]]).
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Remission from [[Cushing disease]] (CD) after [[pituitary neuroendocrine tumor]] resection may be predicted by a postoperative reduction in serum cortisol level.
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Liu et al. retrospectively enrolled 92 consecutive patients with a confirmed diagnosis of [[Cushing's disease]]. Voxel-based analysis was performed to investigate the association between cerebral [[18F positron emission tomography]] uptake and serum [[cortisol]] level. Relatively impaired metabolism of specific brain regions correlated with serum cortisol level was found. Specifically, notable correlations were found in the [[hippocampus]], [[amygdala]], and [[cerebellum]], regions considered to be involved in the regulation and central action of [[glucocorticoid]]s. Moreover, some hormone-associated regions were found in the [[frontal lobe]] [[cortex]] and occipital cortex, possibly mediating the [[cognitive decline]] seen in Cushing's disease. The findings link patterns of perturbed [[brain metabolism]] relates to individual hormone level, thus presenting a substrate for cognitive disturbances seen in Cushing's disease patients, as well as in other conditions with abnormal cortisol levels
((Liu S, Wang Y, Xu K, Ping F, Wang R, Li F, Cheng X. Brain glucose metabolism
is associated with hormone level in Cushing's disease: A voxel-based study using 
FDG-PET. Neuroimage Clin. 2016 Aug 24;12:415-9. doi: 10.1016/j.nicl.2016.08.018. 
eCollection 2016. PubMed PMID: 27622138; PubMed Central PMCID: PMC5008049.
)).