Cushing’s Syndrome and Osteoporosis

By December 5, 2017The Bone Bandits

What is Cushing’s Syndrome?

Cushing’s syndrome refers to a medical condition where your body is exposed to an excessive amount of the hormone cortisol. It affects 1 in 100,000 people and can be caused by use of oral steroids (prednisone) for an extended period of time, excess production of cortisol by your adrenal glands, or by a tumor in your pituitary gland which stimulates increased cortisol levels in your body

Cortisol is often called the “stress hormone” because it regulates many of the changes that take place in your body in response to stress. It aids in controlling your blood sugar, salt, and water levels, and also acts as an anti-inflammatory and suppressant to your immune system. When your bones are exposed to too much cortisol, they can weaken and become more likely to fracture.

How is Cushing’s Syndrome Diagnosed?

There is a wide spectrum of possible presentations of Cushing’s syndrome, from “subclinical” disease with no outward symptoms, to severe Cushing’s syndrome with many obvious symptoms. High cortisol levels can lead to fatty deposits around the face, upper back, and abdomen. It can also cause loss of fat and muscle tone in your legs and arms, easy bruising, high blood pressure, diabetes, and high cholesterol. Many people with Cushing’s will have muscular weakness and an increase in illness or infections.

We commonly use one or more of the following lab tests to diagnose Cushing’s syndrome, which aim to measure cortisol levels in the blood, urine, or saliva. Cortisol levels fluctuate significantly throughout the day, making the diagnosis tricky.

  • 24-Hour Urinary Free Cortisol. This test involves collecting your urine for 24 hours and having it analyzed to determine the amount of cortisol. If levels are significantly elevated greater than 3-times the normal lab reference range, this confirms Cushing’s syndrome.
  • Overnight Dexamethasone Suppression Test. Blood cortisol levels are measured at 8am the morning after taking 1mg of dexamethasone between 11-12pm. The oral steroid (dexamethasone) should suppress your body’s production of cortisol. If it does not, this indicates Cushing’s syndrome.
  • Late-Night Salivary Cortisol. This test involves collecting a sample of your saliva in the late evening, when cortisol levels tend to stabilize. Elevated levels of cortisol in your saliva confirms the diagnosis of Cushing’s syndrome.

How Does Cushing’s Syndrome Impact Your Bones?

Whether your elevated cortisol levels are from within (from an adrenal or pituitary gland tumor) or from the outside (taking oral steroids pills), the end result is damage to your bones. When cortisol reaches your bones, it stimulates bone breakdown osteoclast cells to work overtime. At the same time, cortisol stops the activity of your bone building osteoblast cells. It has also been shown to decrease the ability of your intestine to absorb calcium. Bone loss in Cushing’s syndrome depends on the severity of the disease, or dose and duration of oral steroids… and it can be quite profound in a period of only a few months! Your risk of breaking bones is significantly increased, with spine fractures being the most common.

How Can Those With Cushing’s Syndrome Improve Their Bone Health?

High cortisol levels caused by an adrenal or pituitary tumor can often be treated with surgery and your bones will regain strength. The process of rebuilding bone density may take several months or even years, and some people will still be left with an increased risk of fractures. In this scenario, osteoporosis medications have been shown to be effective in decreasing your risk of breaking bones.

For those who have elevated cortisol levels due to taking oral steroids, the solution is not quite as simple. Many people rely on these medications to prevent their body from rejecting a transplanted organ, or to manage the debilitating symptoms of diseases including rheumatoid arthritis and lupus. To best protect your bones, it is recommended to take the smallest dose of steroids for the shortest duration of time. Your medical provider will need to keep a close eye on your bone density with yearly screenings. Careful management of osteoporosis using a combination of diet, exercise, and medications can decrease your risk of breaking bones when long term use of oral steroids is required.

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