Cortisol A.M.

AM Cortisol levels need to be drawn between 7 - 9 AM.
Due to the circadian rhythm of cortisol levels in serum and plasma, the sample collection time must be noted.

CORTAM

0.5 mL of Li Heparin Plasma (PST)

50 uL

Plasma – EDTA (Lavender)

Tiger top (SST)
Gold top (SST)

Red top

Cortisol a.m. specimen: Collect specimen between 7:00 - 9:00 a.m. Indicate the collection time on specimen container and test requisition. Due to the circadian rhythm of cortisol levels in serum and plasma, the sample collection time must be noted.

Room temperature

Room temperature: 24 hours at 20 - 25ºC

Refrigerated: 4 days at 2 - 8°C

Frozen: 12 months at ­20°C, Freeze only once.

Samples not labled with patient's first and last name and date of birth.
Samples with no collection time.
Grossly hemolyzed

Sun - Sat

Same day

• Pregnancy, contraceptives, and estrogen therapy give rise to elevated cortisol concentrations.
• In samples from patients who have been treated with prednisolone, 6-α-Methylprednisolone or prednisone, falsely elevated concentrations of cortisol may be determined.
• During metyrapon tests, 11-deoxycortisol levels are elevated. Falsely elevated cortisol values may be determined due to cross reactions (see section on analytical specificity).
• Patients suffering from 21-hydroxylase deficiency exhibit elevated 21-deoxycortisol levels and this can also give rise to falsely elevated cortisol results.
• The time of sample collection must be taken into account when interpreting results due to the cortisol secretion circadian rhythm. Severe stress can also give rise to elevated cortisol levels.
• Samples should not be taken from patients receiving therapy with high biotin doses (i.e., > 5 mg/day) until at least 8 hours following the last biotin administration.
• No interference was observed from rheumatoid factors up to a concentration of 600 IU/mL.
• In-vitro tests were performed on 16 commonly used pharmaceuticals. No interference with the assay was found.
• In rare cases, interference due to extremely high titers of antibodies to analyte-specific antibodies, streptavidin or ruthenium can occur. These effects are minimized by suitable test design.
• For diagnostic purposes, the results should always be assessed in conjunction with the patient's medical history, clinical examination, and other findings.

AM Cortisol 6.0 - 18.4 ug/dL
PM Cortisol 2.7 - 10.5 ug/dL

The determination of cortisol is used for the recognition and treatment of functional disorders of the adrenal gland.
 
Cortisol (hydrocortisone) is quantitatively the major glucocorticoid product of the adrenal cortex. The main reason to measure cortisol is to diagnose human diseases which are caused by the overproduction of cortisol in Cushing’s syndrome (CS), deficiency of adrenal steroid excretion in Addison’s disease, and for therapy monitoring (e.g., therapies designed to reduce the excessive production of cortisol in Cushing's syndrome and hormone replacement therapy in Addison's disease). Cortisol plays an important role in the regulation of many essential physiological processes, including energy metabolism, maintenance of electrolyte balance and blood pressure, immunomodulation and stress responses, cell proliferation as well as cognitive functions. Elevated serum levels can be found in stress responses, psychiatric diseases, obesity, diabetes, alcoholism, and pregnancy, which may cause diagnostic problems in patients with Cushing's syndrome. Low levels of cortisol are seen in patients with rare adrenal enzyme defects and after long-lasting stress. For diagnostic purposes the following analyses are used: Total and free cortisol in serum.
 
The secretion of cortisol is mainly controlled by the hypothalamic-pituitary-adrenal axis (HPA). When cortisol levels in the blood are low, a group of cells in a region of the brain called the hypothalamus release corticotropin-releasing hormone (CRH) which causes the pituitary gland to secrete another hormone, adrenocorticotropic hormone (ACTH), into the bloodstream. High levels of ACTH are detected in the adrenal glands and stimulate the secretion of cortisol, causing blood levels of cortisol to rise. As the cortisol levels rise, they start to block the release of CRH from the hypothalamus and ACTH from the pituitary.
 
Normally, the highest cortisol secretion happens in the second half of the night with peak cortisol production occurring in the early morning. Following this, cortisol levels decline throughout the day with lowest levels during the first half of the night. Therefore, the circadian variations of cortisol secretion and the influence of stress have to be considered for the sampling conditions in serum and plasma.