What are the adrenal glands and where are they located?
The adrenal glands are two small glands located on top of the kidneys, one on each side. Despite their name, they belong to the hormonal system and do not have the same function as the kidneys.
Each adrenal gland consists of an outer cortex and an inner medulla. The parts produce different hormones. The blood supply is rich, and the hormones are released directly into the blood.
Changes may be discovered incidentally on CT or MRI of the abdomen. Such a finding is called adrenal incidentaloma and needs to be assessed based on both appearance and hormone production.
What is the function of the adrenal glands?
The adrenal cortex produces cortisol, which helps the body deal with stress and affects metabolism and the immune system. It also produces aldosterone, which regulates salt, potassium, and blood pressure, as well as smaller amounts of hormone precursors.
The adrenal medulla produces adrenaline and noradrenaline. These hormones increase heart rate and blood pressure during stress.
Too little or too much hormone can cause significant symptoms, but the symptoms are often non-specific. Laboratory tests are therefore crucial to assess function.
Cortisol follows a circadian rhythm and is affected by illness, stress and medication. Aldosterone works together with renin and the kidneys. Therefore, hormone tests often require specific sampling times, body position or medication adjustments to be interpreted correctly.
Common adrenal gland changes and symptoms
Many adrenal nodules are benign and hormonally inactive. Some, however, produce cortisol, aldosterone, or catecholamines. Symptoms depend on which hormone is affected.
Overproduction can cause difficult-to-treat high blood pressure, low potassium, headaches, palpitations, sweating, muscle weakness, weight change or altered blood sugar regulation. Hormone deficiency can cause pronounced fatigue, dizziness, low blood pressure, nausea and weight loss.
Read more about adrenal changes and adrenal enlargement.
Excess cortisol can cause muscle weakness, easy bruising, osteoporosis and altered fat distribution. Excess aldosterone can cause high blood pressure and low potassium. Catecholamine-producing tumors can cause attacks with headaches, palpitations and sweating, but the symptoms can also have many more common causes.
When should you seek care for suspected adrenal problems?
Contact healthcare if you have recurring attacks of severe headache, palpitations and sweating, if your blood pressure is difficult to treat or if an adrenal gland abnormality has been discovered. Long-term fatigue and dizziness have many causes but may need to be investigated if they are combined with low blood pressure or weight loss.
Seek emergency medical attention for severe weakness, repeated vomiting, dehydration, confusion, very low blood pressure, or collapse. People with known adrenal insufficiency need to follow their emergency treatment plan in the event of infection or other physical stress.
A newly discovered adrenal nodule is rarely acute but should be assessed in a structured manner.
How are the adrenal glands examined?
The investigation may include blood and urine tests for cortisol, aldosterone, renin, and catecholamine-related substances. The tests needed depend on symptoms and blood pressure.
CT is commonly used to assess size, density, and other imaging features. MRI can be used as a complement and can help characterize certain changes. Previous images are important to see if a finding has changed.
Specialist assessment by an endocrinologist, radiologist and sometimes surgeon may be required. Tissue samples are not routinely used as other methods often provide more reliable guidance.
The investigation often needs to be done in the correct order. If catecholamine overproduction is suspected, the hormonal issue should be assessed before invasive procedures or surgery are planned. In the case of cortisol and aldosterone issues, dynamic tests or repeated samples may be needed to confirm the diagnosis.
If a change is to be followed, the radiologist compares the shape, content, contrast enhancement and growth with previous images. It is the overall image, not a single size limit, that guides further processing.
When might MRI of the adrenal glands be relevant?
MRI can be used when CT does not provide sufficient information, when ionizing radiation should be avoided, or when an adrenal lesion needs to be characterized with specific sequences. The examination may be part of a targeted abdominal MRI.
MRI cannot determine hormone production. Even a change that looks benign may need hormone tests, and a hormonally active change may be small.
The choice between CT, MRI and follow-up depends on appearance, size, previous images, symptoms and laboratory results.
Limitations and next steps
Adrenal gland examination requires a combination of biochemistry and imaging. Symptoms alone are rarely specific, and an imaging finding does not automatically mean disease.
The next step may be to leave the finding without action, follow up with new imaging, treat with medication, or have surgery. The decision is made individually based on hormonal activity and risk assessment.
Test results can be affected by stress, medications, and how the sample was taken. Therefore, abnormal hormone tests often need to be confirmed. A change that does not produce hormones can still be followed if imaging or growth gives reason to do so.