Cushing’s syndrome is named after the person who first described it, the American neurosurgeon Harvey Williams Cushing (1869–1939). It is a metabolic disorder characterized by an excess of glucocorticoids.
The causes, signs, and symptoms are very diverse. In medicine, a clinical picture is always classified as a syndrome when it is accompanied by numerous different symptoms. In Cushing’s syndrome, the number of possible signs is particularly high.
In addition to the relatively common Cushing’s syndrome type I, medicine also distinguishes between Cushing’s syndrome types II and III.
This condition involves physical changes that lead to a decrease in immune function and aesthetic changes.
They usually develop gradually over several years. Only rarely do those affected notice the onset of muscle wasting or the pathological accumulation of fat on the trunk during this time.
Cushing’s syndrome is caused by high levels of cortisol (or cortisone) in the human body. This hormone is produced in the adrenal cortex.
The pituitary gland and the hypothalamus, which acts as the higher control center, in turn regulate the adrenal cortex. Depending on the body’s needs, the pituitary gland either stimulates or inhibits the adrenal cortex.
Cortisone is a vital hormone that performs numerous functions. Primarily, it activates catabolic metabolic processes, thereby providing the body with a variety of energy-rich compounds.
In this way, it supplies the body with the energy it needs in dangerous situations. This is why cortisol is also called the stress hormone.
Medicine distinguishes between four specific forms of this syndrome.
These are:
- exogenous Cushing’s syndrome
- endogenous Cushing’s syndrome
- ACTH-dependent Cushing's syndrome
- primary Cushing's syndrome
Exogenous Cushing’s syndrome
“Exogenous” means “from outside.” Exogenous Cushing’s syndrome therefore does not result from a pathological overproduction of cortisone in the body.
It is usually caused by an external source. This is the case with cortisone medication.
Due to its immunosuppressive and anti-inflammatory properties, this substance is effective in treating numerous diseases.
It plays a role in the following conditions, among others:
Typically, the active ingredient enters the patient’s bloodstream directly. However, this can lead to a severe overdose in some cases.
The syndrome immediately exerts its destructive effects once the so-called Cushing threshold is exceeded. For this reason, it is important that cortisone therapy always be administered under medical supervision.
Endogenous Cushing’s syndrome
Endogenous Cushing’s syndrome, on the other hand, develops without the administration of cortisone. In this rare form of the disease, the adrenal gland produces too much cortisol.
In healthy people, the pituitary gland controls the production of this hormone through complex processes. It produces the neurotransmitter adrenocorticotropic hormone (ACTH), which sends a signal to the adrenal cortex to increase production. This stimulates the release of cortisone.
The production of ACTH, in turn, depends on the concentration of corticotropin-releasing hormone (CRH) from the hypothalamus. The more CRH the hypothalamus produces, the higher the production of ACTH.
Cortisol inhibits the production of CRH, thereby maintaining a stable cycle. In endogenous Cushing’s syndrome, this cycle is interrupted or disrupted at various points.
ACTH-dependent Cushing’s syndrome
ACTH-dependent Cushing’s syndrome is a specific form of endogenous Cushing’s syndrome. It can also be triggered by even a small tumor in the pituitary gland, which causes sustained production of ACTH. The main cause of this form of Cushing’s syndrome is therefore unregulated and uncontrolled overproduction of ACTH.
Primary Cushing’s syndrome
Primary Cushing’s syndrome, on the other hand, is usually associated with a tumor located directly in the adrenal cortex. In addition, some cases involve excessive growth of adrenal tissue. As a result, this type of Cushing’s syndrome can develop even without a malignant tumor.
Cortisol performs numerous different functions in the body. For this reason, Cushing’s syndrome triggers a wide range of symptoms.
There is always a massive redistribution of fat toward the midsection. This condition is known as central obesity.
Furthermore, in people with this condition, body fat also accumulates in the face and between the shoulders. This results in a round, full-moon face and what is known as a “bull neck.”
Regardless of weight, these areas are always filled with fat deposits, while the arms and legs remain completely slender. In addition, particularly high cholesterol levels are often observed.
By Ozlem Celik, Mutlu Niyazoglu, Hikmet Soylu, and Pinar Kadioglu - http://mrmjournal.biomedcentral.com/articles/10.1186/2049-6958-7-26, CC BY 2.5, Link
At the same time, there is increased insulin production and elevated blood sugar levels. This results in blood test results that closely resemble those of diabetes.
For this reason, doctors often initially mistake Cushing’s syndrome for diabetes mellitus. However, it is clearly recognizable due to the persistent feeling of thirst and frequent urination.
Furthermore, it is characterized by a rapid breakdown of muscle fibers and bone tissue. This leads to both persistent bone loss and pathological muscle weakness.
The skin is also increasingly damaged by Cushing’s syndrome. After only a short time, so-called “parchment-like skin” develops. This medical term describes very thin skin that can be injured even by minimal force.
In addition, red streaks often form on the abdomen, along with acne and boils. Wound healing is also significantly slowed. Most people also suffer from persistent high blood pressure.
In addition to an extremely high susceptibility to infections, mental health disorders may also occur in some cases. These include depression, reduced sexual function in men, and virilization in women.
Even for experienced physicians, diagnosing Cushing’s syndrome is not always easy. It is therefore crucial that the treating physician recognizes the connection between all the symptoms and interprets them correctly.
This allows for a physical examination. Various tests and a medical history questionnaire then provide insight into the origin and nature of the disease.
In most cases, collecting urine over a 24-hour period forms the core of the testing. This allows the doctor to clearly determine the concentration of cortisol released.
In addition, the dexamethasone suppression test has also become standard practice. This test allows the doctor to determine the exact cause of a disruption in the cortisol production feedback loop.
Finally, a CRH test is routinely performed. This test bears strong similarities to the dexamethasone suppression test but focuses primarily on the concentration of CRH in the body.
The goal of treatment for exogenous Cushing’s syndrome is the gradual reduction of cortisone.
However, treating endogenous Cushing’s syndrome is more difficult, as doctors must address the underlying cause of the condition. This is usually a malignant or benign tumor.
Doctors usually have to surgically remove these tumors to reduce cortisol production.
In addition, numerous medications can also be helpful. If neither of these approaches is effective, most specialists prescribe comprehensive radiation therapy or chemotherapy.
