Introduction:
Glands are vital structures present throughout the body. These glands produce and secrete certain hormones that target specific organs in the body. The hormones secreted by the glands regulate bodily functions and maintain a metabolic balance throughout the body. Each gland is site and function specific. However, the adrenal gland is a multifunctional gland that regulates blood pressure, immune function, metabolism, stress response, and many others.
Adrenal glands come as a pair, one on top of each kidney. Hence they are also known as the suprarenal glands. The gland anatomy comprises an outer zone known as the cortex that secretes hormones like cortisol and aldosterone, whereas the inner zone is the medulla that secretes adrenaline and noradrenaline. These hormones control many vital functions of the body, such as:
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Blood sugar levels.
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Blood pressure.
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Stress response.
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Salt-water balance.
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Sex hormones.
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Pubertal development.
What Are the Diseases Affecting the Adrenal Glands?
The most common way the adrenal gland may affect the body is by producing excessive or too few hormones. Based on the hormones produced, adrenal gland disorders can be classified into:
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Hyperactivity: Resulting in excessive production of hormones. Conditions resulting in hyperactivity are:
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Cushing’s Syndrome: This condition is caused by excess cortisol resulting in fatty deposits throughout the body.
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Hyperaldosteronism: Excess production of aldosterone results in hyperaldosteronism.
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Adrenogenital Syndrome: This inherited genetic condition is caused by a deficiency of adrenocortical enzyme steroids.
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Hypoactivity: Resulting in decreased hormone production. Conditions resulting in hypoactivity are:
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Addison’s Disease: This condition is characterized by chronic adrenal insufficiency. It is a rare disorder that may be caused by autoimmune disorders, infections, or tumors.
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Adrenal Crisis: An acute adrenal insufficiency results in an adrenal crisis, also known as the Addisonian crisis.
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Congenital Adrenal Hyperplasia: In this condition, there is a deficiency of a specific enzyme necessary to produce cortisol or aldosterone. However, excess production of the male sex hormone androgen results in male characteristic features in girls and precocious puberty in boys.
What Is Hyperaldosteronism?
Excess aldosterone production from one or both adrenal glands may result in hyperaldosteronism. The hormone aldosterone, produced by the adrenal cortex, is vital in regulating blood pressure and helps maintain electrolyte balance (sodium and potassium) in the body. Aldosterone signals the kidney to absorb sodium and excrete potassium, thereby maintaining the salt and water balance in the body and regulating blood pressure. Excess aldosterone may impair the water-electrolyte balance, resulting in fluid accumulation in the body and, thereby, high blood pressure.
What Are the Types of Hyperaldosteronism?
Hyperaldosteronism may be classified into two types: primary or secondary. Primary hyperaldosteronism is due to a tumor or growth in the adrenal gland, whereas secondary hyperaldosteronism occurs when extra-adrenal conditions cause excess aldosterone production. Secondary hyperaldosteronism could be genetic, dietary, or associated with high blood pressure, cardiac diseases, or liver diseases.
What Is Primary Hyperaldosteronism?
A benign or rarely malignant tumor in the adrenal gland may result in primary hyperaldosteronism. It is also known as Conn’s syndrome. The adrenal gland produces excessive aldosterone, which results in high blood pressure and abnormal blood potassium levels. This condition, left untreated, could result in fatal complications such as heart attack, stroke, or even cardiac failure. Hence early diagnosis and prompt treatment are crucial.
Who Is More Prone to Developing Primary Hyperaldosteronism?
Primary hyperaldosteronism may affect any individual but a few risk factors associated are:
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Individuals with hypokalemia (low potassium levels).
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Young (less than 30 years) individuals diagnosed with high blood pressure.
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Patients on medical management for hypertension and high blood pressure.
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Pre-diagnosed adrenal mass.
What Causes Primary Hyperaldosteronism?
Primary hyperaldosteronism, or Conn's syndrome, is primarily due to a benign tumor in the adrenal gland. It may also result from bilateral adrenal hyperplasia (enlargement of the adrenal gland). Rarely does it present as an inherited condition. Cancers of the adrenal gland though rare, are known to cause primary hyperaldosteronism.
What Are the Symptoms of Primary Hyperaldosteronism?
The symptoms are as mentioned below:
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High blood pressure.
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Fatigue.
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Increased thirst.
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Frequent urination.
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Abnormal vision.
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Muscle weakness and cramps.
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Headache.
How Is Primary Hyperaldosteronism Diagnosed?
Blood tests are usually the first choice to diagnose primary hyperaldosteronism. Assessing the blood levels of hormone-like aldosterone and renin (which primarily act on the kidneys) and the electrolytes such as sodium and potassium levels can conclude the diagnosis of primary hyperaldosteronism. However, imaging tests prove crucial in differentiating primary from secondary hyperaldosteronism. In addition, they help detect adrenal gland tumors that are predominantly responsible for primary hyperaldosteronism.
What Is the Role of Imaging in Diagnosing Primary Hyperaldosteronism?
Imaging has no role in the initial diagnosis of hyperaldosteronism; however, it is a crucial tool to differentiate primary from secondary hyperaldosteronism. In addition, it is vital to identify the cause of primary hyperaldosteronism, as the management protocol greatly differs based on the etiology. For example, a tumor in the adrenal gland requires surgical management; however, adrenal gland hyperplasia may be managed medically. The imaging techniques applied in the diagnosis are mentioned below:
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Ultrasound: Ultrasound is a handy diagnostic tool that is non-invasive and cost-effective. It is highly safe as there is no radiations involved in this procedure. Abdominal ultrasound is mainly preferred to diagnose adrenal adenomas (benign tumors). Ultrasound uses high-frequency sound waves to visualize the organs and tissues of the body. However, ultrasound is beneficial if the adenomas are of appreciable size. Smaller adenomas may not be easily imaged, thus compromising the sensitivity of the procedure.
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Computerized Tomography (CT): CT is the most preferred diagnostic tool to image the adrenal gland. An abdominal CT can help detect an adrenal mass or a change in the size or structure of the adrenal gland. It is a non-invasive and more precise diagnostic imaging test. The specificity and sensitivity are higher than a conventional ultrasound to diagnose adrenal tumors. However, in patients with multiple bilateral nodules, CT may not prove beneficial in differentiating adrenal hyperplasia from benign adenomas; hence biopsy would be more confirmatory. High-resolution CT (HRCT) is more reliable in differentiating a benign adrenal tumor from its malignant counterpart.
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Magnetic Resonance Imaging (MRI): MRI uses a magnetic field and radio waves to image body parts. Chemical-shift MRI is more specific and sensitive in the differentiation of benign and malignant adrenal tumors, as benign tumors comprise fat, whereas malignant tumors rarely contain fat.
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Nuclear Imaging: Nuclear imaging involves using a radiotracer. Tumor cells tend to have an increased uptake of the radiotracer material, which can be easily visualized on the scan. However, primary hyperaldosteronism must be diagnosed clinically and with biochemical tests before nuclear imaging because a similar tracer uptake will be found in secondary hyperaldosteronism.
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Angiography: Selective angiography of the adrenal gland may be helpful to a certain extent. In angiography, a contrast material is injected into the circulation. However, since the adenomas are relatively smaller and not particularly vascular, angiography has a limited role in primary hyperaldosteronism.
Conclusion:
Primary hyperaldosteronism requires thorough investigation and precise diagnosis for efficient management. A delay in diagnosis could result in grave complications and be life-threatening. Therefore, diagnostic imaging is pivotal in planning the appropriate treatment and is an important prognostic indicator.
