Understanding Your Diagnosis: PBMAH and BMAD

Receiving a diagnosis of Primary Bilateral Macronodular Adrenal Hyperplasia (PBMAH) can feel overwhelming, especially because the name itself is a mouthful and the condition is quite rare. If you are like many people with this condition, you may have discovered it “by accident” during a CT scan or MRI for an unrelated issue, such as back pain or a digestive problem ^[1].

This page will help you understand what is happening in your body and why your medical team might be using different names to describe the same thing.

Understanding the Name Change

In the world of medicine, names for diseases often change as scientists learn more about them. You may hear several different terms:

• PBMAH: Primary Bilateral Macronodular Adrenal Hyperplasia. This has been the standard name for years.
• BMAD: Bilateral Macronodular Adrenal Disease.
• BMACD: Bilateral Macronodular Adrenal Cortical Disease.

In 2022, the World Health Organization (WHO) updated its classification framework to group macronodular and micronodular lesions under adrenal cortical nodular disease, including BMACD and BMAD ^[2][3]. This change reflects a new understanding that the “lumps” on the adrenal glands are not just simple overgrowth (hyperplasia), but are specific nodules that can have their own genetic signatures ^[4][5]. Whether your doctor calls it PBMAH or BMAD, they are referring to the same bilateral nodular condition ^[6][7]. It is important to know that BMAD/PBMAH describes the structural disease on your glands; your actual cortisol autonomy is assessed separately, as some patients have nonfunctional nodules.

How Common is This?

PBMAH is a rare cause of Cushing syndrome (the state of having too much cortisol in the body). It accounts for less than 2% of all Cushing syndrome cases ^[8][9].

However, because imaging technology is becoming so advanced, doctors are finding these “adrenal incidentalomas” more frequently. Among people who have nodules on both adrenal glands discovered incidentally, about one-third may be found to have PBMAH/BMAD when cortisol excess is present ^[1][10]. While it is rare in the general population, it is a well-recognized condition among adrenal specialists.

What Does ‘ACTH-Independent’ Mean?

In a healthy body, a small gland at the base of the brain called the pituitary gland acts like a thermostat. It sends out a hormone called ACTH (Adrenocorticotropic Hormone) to tell the adrenal glands when to make cortisol.

In functional PBMAH, the “thermostat” is broken, but not in the brain. Instead, the adrenal glands themselves have become “autonomous.” This is called ACTH-independent cortisol production ^[11].

• The adrenal nodules make cortisol on their own, without waiting for a signal from the brain ^[12].
• Because there is already extra cortisol in your blood, your brain correctly senses the “heat” and stops sending out the ACTH signal.
• As a result, your blood tests will typically show cortisol levels that fail to suppress normally and very low or suppressed ACTH levels ^[11]. Low ACTH supports adrenal autonomy, though it does not by itself prove PBMAH or exclude every other cause.

Why Are Both Glands Affected?

Unlike a single adrenal tumor, PBMAH affects both glands. This is often due to genetic factors that make the adrenal tissue more likely to grow nodules.

One of the most significant discoveries in this field is the ARMC5 gene. Many people with PBMAH have a germline mutation in this gene that can be inherited from a parent ^[13]. This mutation acts like a “first hit” to the adrenal glands, making them susceptible. Over time, individual nodules may undergo a “second hit” or further genetic changes, causing them to grow and begin pumping out excess cortisol ^[14][5].

“Misplaced” Signals

In some people with BMAD, the adrenal glands develop “aberrant receptors.” Essentially, the glands start listening to the wrong signals. For example, instead of listening to ACTH, the adrenal glands might start responding to:

• GIP (Gastric Inhibitory Polypeptide): A hormone released by your gut when you eat. This can cause cortisol levels to spike specifically after meals ^[15].
• Vasopressin: A hormone that regulates water balance.
• Posture: Some people’s adrenal glands may even release cortisol in response to standing up or changing positions ^[11].

Navigating the Emotional Impact

It is completely normal to feel a mix of confusion and anxiety after this diagnosis. Because it is often found incidentally, you may have gone into a scan for a minor issue and come out with a diagnosis of a rare condition ^[16].

The range of the disease is very broad. Some people have “overt” Cushing syndrome with clear physical symptoms, while others have “mild autonomous cortisol secretion” (MACS), where the cortisol fails to suppress on lab tests but isn’t yet causing obvious physical changes ^[17][18]. This “gray area” can be frustrating, as you and your doctor must decide whether to monitor the nodules or move toward treatment, such as surgery or medication ^[19][20].

Remember that an incidental finding is a starting point, not a final destination. Your medical team will use hormone tests and specialized imaging to create a plan that fits your specific cortisol levels and symptoms ^[19].