Cushing's Syndrome vs PCOS: When to Suspect

When weight climbs for no clear reason, periods turn irregular, and facial hair increases, most Malaysian women think straight away of PCOS. That instinct is reasonable, because PCOS is far more common, affecting roughly 10 to 13 percent of women of reproductive age. But there is a rarer condition that can masquerade as PCOS, namely Cushing’s syndrome. The two share several surface symptoms, yet their underlying causes are completely different. This article helps you understand when your symptoms are more than “just PCOS”, and when a doctor should investigate for Cushing.

The basic difference between the two conditions

PCOS arises from a mix of high androgen hormones, disrupted ovulation, and often insulin resistance. Cushing’s syndrome arises from excess cortisol, the “stress” hormone produced by the adrenal glands. That cortisol excess can come from a small tumour in the pituitary or adrenal gland, or, more commonly, from long-term use of steroid medication (for example prednisolone for severe asthma, lupus, or arthritis).

Understanding this difference in prevalence matters so you do not panic. PCOS is common; true Cushing’s syndrome (arising from the body’s own glands) is very rare, with an estimated 2 to 3 new cases per million people each year. So for the vast majority of Malaysian women with overlapping symptoms, the answer remains PCOS. Cushing only needs to be investigated when specific warning signs appear, which we explain below.

One nuance that is rarely spelled out: many specialists distinguish between “endogenous” Cushing (excess cortisol from your own glands, which is very rare) and “iatrogenic” or “exogenous” Cushing (caused by steroid medication, which is seen far more often in clinics). For Malaysian women, this second type is the most relevant in everyday life, because steroids are easy to obtain and are sometimes used without close monitoring. We explain this further below.

The overlapping symptoms that cause confusion

The reason these two conditions are so often confused is that many of their outward symptoms look similar:

• Weight gain, especially around the abdomen
• Irregular or absent periods
• Acne and oily skin
• Excess hair on the face, chest or abdomen (hirsutism)
• High blood pressure
• High blood sugar or prediabetes

Look at this list and almost every item can occur in PCOS too. That is precisely why a woman with Cushing is sometimes mislabelled as having PCOS for years. In the endocrine literature, even specialists describe telling mild Cushing apart from PCOS as a persistent “diagnostic quandary”, because mild Cushing may lack the classic signs and even its basic laboratory tests can sometimes be normal. So overlapping symptoms alone cannot tell the two apart. What sets them apart are the specific signs that appear only in Cushing.

Cushing-specific signs that do not occur in PCOS

This is the most important part. A few physical signs almost never occur in true PCOS, so their presence should raise suspicion for Cushing:

• Purple or red stretch marks (striae) that are wide, usually more than 1 centimetre, across the abdomen, thighs or arms. Ordinary stretch marks after pregnancy or weight gain are pale and silvery; these dark purple, broad ones are different.
• Easy bruising without a hard knock, because cortisol thins the skin and weakens small blood vessels.
• Proximal muscle weakness, meaning difficulty rising from a low chair, climbing stairs, or raising your arms to hang laundry. This sign is reported in 40 to 70 percent of patients with active Cushing.
• A round, flushed face (known as “moon face” and plethora), plus fat pads at the back of the neck and upper shoulders (sometimes called a “buffalo hump”).
• Fat concentrated in the trunk while the arms and legs grow thinner, a pattern different from the more general weight gain of PCOS.

There is also a hormonal clue: in PCOS, testosterone levels are usually high, whereas in mild Cushing they are often normal or lower. The same goes for other androgens such as DHEAS and androstenedione, which tend to be high in PCOS but within the normal range in most Cushing patients. So if you have many Cushing-type signs but your androgen tests come back normal or low, that is another reason to look further.

It is also important to understand that these specific signs carry more weight when several appear together and worsen over time. A single thin stretch mark or one isolated bruise is not a sign of Cushing on its own. What is concerning is the combination, for example a newly round face, plus easy bruising, plus weakening muscles, all within a few months.

Why steroids deserve attention in Malaysia

The most common cause of Cushing seen in practice is not a tumour but long-term steroid use. In Malaysia this is relevant for several reasons. First, whitening creams or skin creams bought without a prescription sometimes contain strong steroids that are not clearly labelled, and prolonged use over large areas can be absorbed by the body. Second, some traditional remedies or over-the-counter “joint medicines” have been found illegally adulterated with steroids. Third, patients with severe asthma, lupus, or arthritis who genuinely need steroids may develop Cushing features as a side effect of legitimate treatment.

So when you see a doctor, it is very important to list everything you take or apply, including traditional remedies, supplements, face creams, and joint medicines, not just prescription drugs. If your Cushing features come from a steroid, the solution is completely different from tumour-related Cushing, and steroids must never be stopped abruptly because the body needs time to recover. The decision to reduce or stop a steroid must be made by a doctor, not by yourself. The registration status of a product can also be checked through NPRA before you keep using it.

When a doctor should investigate for Cushing

The 2023 international PCOS guideline advises ruling out other conditions when the clinical picture is atypical for PCOS. Among the red flags doctors watch for:

• Hirsutism or androgen symptoms that appear suddenly and worsen quickly over months, rather than gradually since adolescence
• Signs of virilisation such as a deepening voice or an enlarging clitoris, which are not consistent with ordinary PCOS
• The presence of the Cushing-specific signs above (purple striae, easy bruising, muscle weakness)
• High blood pressure or diabetes that is hard to control in a young woman, alongside Cushing features

If such warning signs are present, a doctor may recommend cortisol screening tests. Common tests include the 1 mg overnight dexamethasone suppression test, late-night salivary cortisol (usually two samples), or 24-hour urinary free cortisol. Importantly, these tests can give false positives if you take oestrogen-containing contraceptive pills, have severe obesity, depression, sleep problems, or high emotional stress. This situation is called pseudo-Cushing and must be interpreted by a specialist, not self-assessed.

What happens during cortisol testing

Understanding these tests in advance can ease anxiety. For the overnight dexamethasone suppression test, you swallow a single 1 mg dexamethasone tablet late at night (usually around 11 pm), then your blood is drawn the next morning around 8 to 9 am to measure cortisol. In healthy people, dexamethasone should “switch off” cortisol production, so the morning level drops low. If cortisol stays high, that is one warning sign.

For the late-night salivary cortisol test, you collect a saliva sample at home at night, because cortisol should be at its lowest then. Avoid eating, drinking, or brushing your teeth right before sampling because it can affect the result. For the 24-hour urine test, you must collect all of your urine over a full day into a special container. No single test is perfect, so specialists often combine more than one test and interpret the results together with your clinical picture. If the screening test is unclear, you may need a referral to an endocrinologist for further testing.

Practical steps for Malaysian women

If you already have a PCOS diagnosis but feel that “something is not right”, the first step is still simple. You can visit a KKM Klinik Kesihatan, which charges around RM1 per visit for citizens and includes basic investigations. The medical officer can assess your symptoms and, if needed, refer you to a hospital O&G or endocrine clinic for cortisol testing. Follow-up with a specialist in a government hospital is usually around RM5. Private clinics cost more and vary, so mention your concerns early.

Bring a written list of your symptoms, especially when they started and how fast they changed. Take photos of any striae or bruising, since these help the doctor’s assessment. Include a full list of the medicines, supplements, and creams you use. If you have only just been diagnosed and are still gathering information, the guide for the newly diagnosed can help you organise your questions.

Questions to bring to your doctor

• Do these new symptoms fit PCOS alone, or should they be investigated for another condition?
• Based on my androgen levels, are they high (as expected in PCOS) or normal to low?
• Could any of the medicines, creams, or supplements I use be contributing to these symptoms?
• If a cortisol test is needed, which one, and how should I prepare?
• If the results are unclear, should I be referred to an endocrinologist?

One thing to remember: although Cushing is rare, it is a treatable condition once identified, and if left untreated it carries serious long-term health risks including high blood pressure, diabetes, and heart problems. So investigating is not a waste of time. On the other hand, for most women, confirming that this really is PCOS also brings peace of mind and opens the path to the right treatment, including monitoring the long-term risks such as type 2 diabetes and heart health that are also linked to PCOS. Whatever the result, do not delay seeing a doctor if your symptoms worsen quickly or you notice muscle weakness, easy bruising, or new purple striae.