Perimenopause vs Cushing's Syndrome: Key Differences Explained
Weight gain, mood changes and irregular periods appear in both perimenopause and Cushing's syndrome. Here is how to tell them apart and what tests help.
An Unlikely Mix-Up That Still Happens
At first glance, perimenopause and Cushing's syndrome seem like very different conditions. One is a normal hormonal transition that every woman goes through; the other is a rare disorder caused by chronically elevated cortisol. Yet in practice, women with Cushing's syndrome are frequently misdiagnosed for years, and perimenopause is one of the diagnoses that gets applied while the real cause goes undetected. The overlap is genuine: weight gain, menstrual irregularity, mood disturbances, sleep problems, and fatigue appear in both. Since Cushing's syndrome typically develops slowly and affects women more often than men, the perimenopausal age group bears a disproportionate share of delayed diagnoses. Knowing what to look for in each condition can prompt earlier and more accurate testing.
What Causes Cushing's Syndrome
Cushing's syndrome results from prolonged exposure to high levels of cortisol. The most common cause is a benign tumour on the pituitary gland, called Cushing's disease, which causes the pituitary to produce excess ACTH. This stimulates the adrenal glands to overproduce cortisol. Less commonly, a tumour on an adrenal gland itself secretes cortisol directly, or a tumour elsewhere in the body produces ectopic ACTH. Long-term use of corticosteroid medications such as prednisolone is another well-established cause. Cortisol at elevated levels disrupts almost every system in the body, affecting fat distribution, blood sugar regulation, immune function, bone density, and mood. It is a slow-moving condition, which is part of why it is so often missed.
Signs That Suggest Cushing's Syndrome Rather Than Perimenopause
Several features are more specific to Cushing's syndrome and should trigger further investigation. Purple or reddish stretch marks, particularly on the abdomen, thighs, or arms, that are wider than typical stretch marks are a classic sign. Fat redistribution that creates a rounded face, a fatty lump between the shoulders sometimes called a buffalo hump, and a full, rounded midsection while the limbs remain thin is characteristic of excess cortisol. Easy bruising, thin fragile skin, and slow-healing cuts point toward Cushing's. Muscle weakness, especially in the thighs and upper arms, that makes it hard to climb stairs or rise from a chair is another indicator. Unexplained osteoporosis or fractures in a relatively young woman, or new-onset type 2 diabetes, are further reasons to consider a cortisol investigation.
Signs That Suggest Perimenopause Rather Than Cushing's
Hot flashes and night sweats are not features of Cushing's syndrome and remain among the clearest indicators of perimenopause. The typical perimenopause weight gain tends to be more evenly distributed or centred on the waist without the dramatic facial and neck fat accumulation seen in Cushing's. Changes in menstrual frequency and volume that track with the gradual decline in oestrogen and progesterone are characteristic of perimenopause. Vaginal dryness, urinary symptoms, and changes in sexual comfort associated with genitourinary syndrome of menopause do not occur in Cushing's. If symptoms fluctuate with the menstrual cycle or follow the predictable pattern of a lengthening cycle, perimenopause is far more likely.
Testing and Diagnosis
Perimenopause is usually diagnosed clinically, supported by FSH and oestradiol measurements and a thorough history of cycle changes and symptoms. Cushing's syndrome requires specific endocrine testing. Initial screening typically involves a 24-hour urine free cortisol test, a late-night salivary cortisol test measuring cortisol at its natural low point, or an overnight low-dose dexamethasone suppression test. If screening is abnormal, further imaging and more detailed suppression tests follow to identify whether the source is pituitary, adrenal, or ectopic. If your weight gain has an unusual distribution, you have unexplained bruising or fragile skin, or your blood sugar and blood pressure are both rising, discussing cortisol screening with your doctor is sensible.
Living With Either Condition and Tracking What Matters
Cushing's syndrome is treated by removing or managing the source of excess cortisol, whether that is surgery to remove a tumour, reducing steroid medication under medical supervision, or using drugs that block cortisol production. Recovery is possible for many people, though it can take time after treatment for the body to recalibrate. Perimenopause is managed through a combination of lifestyle adjustments and, for many women, hormone therapy to ease the transition. If you have either condition, consistent symptom tracking is genuinely useful. Noting changes in energy, mood, sleep, body shape, and menstrual patterns over weeks and months creates a record that helps doctors recognise patterns that might not be apparent in a single consultation. PeriPlan allows you to log and track symptoms over time, giving you a more complete picture to bring to your appointments.
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