Cortisol Test
Cortisol is a steroid hormone, which is essential for healthy functioning of the body. Cortisol is produced by the adrenal glands, which are located at the top of the kidneys. A hormone known as ACTH (adrenocorticotropic hormone), which is produced by the pituitary gland, is responsible for stimulating the production and release of cortisol. The body increases levels of cortisol when it is under stress and cortisol also helps to control the immune system. The release of cortisol works in a daily pattern, with levels at their highest at around 8am and their lowest during the evening.
When is the test used?
Cortisol tests are primarily used to diagnose Cushing’s syndrome and Addison’s disease; these are serious conditions, which affect the production of cortisol in the body. Cushing’s syndrome is caused by high levels of cortisol, while Addison’s disease is caused by levels of cortisol which are too low. If tests reveal abnormal concentrations of cortisol in the blood or urine, further tests may be ordered to determine the cause of abnormal production.
The test is usually ordered when a patient has symptoms associated with Cushing’s syndrome or Addison’s disease. Symptoms of Cushing’s syndrome include:
- High blood pressure
- Weakness in the muscles
- Muscle wastage
- Obesity and unexplained weight gain
Symptoms of Addison’s disease include:
- Low blood pressure
- Exhaustion
- General weakness and a lack of energy
- The appearance of pigment on the skin
How is the test performed?
The test is done by taking a blood sample from a vein in the arm; a sample is usually taken at 8am at the morning when cortisol levels should be at their highest; the test will then be repeated late at night when levels should be at their lowest. Doing tests at different times of the day allows doctors to evaluate the daily pattern of cortisol secretion.
Urine tests may also be used to measure cortisol levels; this involves a 24 hour test, which measures the secretion of cortisol over a 24 hour period.
What do the test results mean?
High levels of cortisol may indicate that a patient has Cushing’s syndrome, while low levels of cortisol may suggest that a patient has Addison’s disease. If a person has Cushing’s syndrome their daily pattern of cortisol secretion is usually interrupted and irregular and this should be visible on the results of the tests.
If a patient is suspected of having Addison’s disease, further tests will be ordered as the result of the cortisol test is not sufficient to form a diagnosis.
Additional factors such as physical or emotional stress, pregnancy, hyperthyroidism and obesity may also cause cortisol levels to increase.
Specific Blood Tests
- Specific Blood Tests
- Factor V Leiden Mutation and PT 20210 Mutation
- Ferritin Test
- Fibrinogen
- Fructosamine
- FSH Test
- G6PD
- Gastrin
- GGT
- Glucose test
- Growth hormone
- Haemoglobin
- Haptoglobin
- HbA1c test
- HDL Cholesterol Test
- Helicobacter Pylori test
- Heparin Anti-Xa
- Hepatitis A Virus
- Hepatitis B Virus
- Hepatitis C Virus
- Her-2/neu Testing
- Heterophil Antibody Titre
- High-Sensitivity C-Reactive Protein
- HIV Antibody Test
- HIV Resistance Testing
- HIV Viral Load
- IGF-1
- Immunoreactive Trypsin
- Insulin
- Iron test
- LDH
- LDL Cholesterol Test
- Lead Test
- LH Test
- Lipase Test
- Lipoprotein (a)
- Lithium
- Lupus Anticoagulant
- Lyme disease test
- Maternal screening
- Mercury, Urine and Blood
- Mycophenolic Acid
- Myoglobin Test
- Oestrogen
- Osmolality
- Overdose Drug Test
- Paracetamol
- Parathyroid Hormone
- Parvovirus B19
- PCV
- Pertussis
- Phenobarbital
- Phenytoin
- Phospate
- Platelet Count
- Porphyrins
- Potassium Test
- Prealbumin Test
- Procalcitonin
- Progesterone Test
- Prolactin
- Prostate-Specific Antigen
- Protein 24 Capsid Antigen
- Protein C and Protein S
- Protein Electrophoresis Immunofixation Electrophoresis
- Prothrombin Time
- PSEN1 Test
- PTH
- Reticulocyte count
- Rheumatoid factor
- Rubella test
- Salicylic Acid
- Serotonin
- Sex Hormone Binding Globulin
- Sickle Cell Test
- Sirolimus
- Smooth Muscle Antibody
- Sodium Test
- Soluble Mesothelin-Related Peptides
- Synacthen Test
- Syphilis Test
- Tacrolimus
- Tau protein
- Testosterone Test
- Theophylline & Caffeine
- Thiopurine s-methyltransferase
- Thyroglobulin (Tg)
- Thyroid peroxidase antibody (TPOAb)
- Thyroid-Stimulating Hormone
- Thyroxine
- TIBC, UIBC & Transferring
- TORCH Test
- Total Protein test
- Triiodothyronine
- Triglycerides Test
- Troponin test
- Urea test
- Uric Acid
- Valproic Acid
- Vancomycin
- Very Low Density Lipoprotein
- Vitamin B12 and Folate
- Vitamin D
- West Nile Virus
- White blood cell differential count
- Zinc Protoporphyrin
- Activated Clotting Time
- ACTH
- Albumin
- Aldosterone and Renin
- Alkaline Phosphatase Test
- Allergen-Specific IgE Antibody Test
- Alpha-1 Antitrypsin
- Alpha-Fetoprotein
- ALT
- AMA
- Ammonia
- Amylase Test
- Angiotensin Converting Enzyme
- Antinuclear Antibody
- Antithrombin
- Apolipoprotein A-I
- Apolipoprotein E Genotyping
- aPTT
- AST
- Bicarbonate
- Bilirubin
- Blood cultures
- Blood film
- Blood Gas Tests
- Blood Ketones
- Brain Natriuretic Peptide
- BRCA-1 & BRCA-2
- CA 125
- Cancer Antigen 15-3
- Cancer Antigen 19-9
- C-peptide
- Caeruloplasmin
- Calcitonin
- Calcium Test
- Carbamazepine
- Cardiac Risk Assessment
- Cardiolipin Antobodies
- Catecholamines, Plasma and Urine
- CCP
- CD4 and CD8
- CEA Test
- CF Gene Mutation Testing
- Chickenpox and Shingles Tests
- Chloride Test
- Cholesterol Test
- Chlorinesterase Test
- Chromogranin A
- Ciclosporin
- CMV
- Coagulation Factors
- Coeliac Disease Tests
- Copper
- Cortisol Test
- Creatine Kinase CK-MB Test
- Creatine Kinase Test
- Creatinine
- Creatinine Clearance
- C-Reactive Protein
- Cystatin C
- D-Dimer
- DHEAS
- Digoxin
- Direct LDL cholesterol
- eGFR - Calc. Creatinine Clearance
- Electrolytes
- Epstein-Barr Virus Antibodies
- Erythrocyte Sedimentation Rate
- Erythropoietin
- Ethanol
Blood Test Guide
- Blood Tests
- Types of blood tests
- what to expect
- What are the risks of blood tests?
- What do blood tests show?
- Specific Blood Tests