How to Get Diagnosed with POTS and Mast Cell Activation Syndrome (MCAS)

When I first heard the words POTS and Mast Cell Activation Syndrome (MCAS), I had no idea what they meant, let alone how they related to me.

I was already knee-deep in recovery from breast cancer, 15 surgeries, and countless complications, including infections from my breast reconstruction, breast implant illness, and eventually, hernia mesh rejection.

I knew something deeper was going on—but no one seemed to know what.

It wasn’t until a dear friend, a DNP who specializes in chronic illnesses like POTS & MCAS, reached out and said, “Christi, I think you might have Mast Cell Activation Syndrome,” that the pieces finally began to fall into place.

If you’re reading this, you’re likely in that confusing, exhausting in-between space—knowing something’s wrong, but unsure how to get answers.

This guide is for you.

What Are POTS and MCAS?

POTS (Postural Orthostatic Tachycardia Syndrome) is a type of dysautonomia that causes your heart rate to increase dramatically when you stand. You might feel lightheaded, shaky, brain-fogged, fatigued, or even faint.

MCAS (Mast Cell Activation Syndrome) happens when your mast cells release too many inflammatory chemicals like histamine, prostaglandins, and cytokines—even without a true allergic trigger. This can lead to symptoms across every body system: rashes, GI distress, flushing, itching, headaches, low blood pressure, and more.

These are invisible illnesses that often go misdiagnosed or completely missed. But they’re real. And they’re treatable—once you know what you’re dealing with.

How to Get Diagnosed: Step-by-Step

1. Track Your Symptoms

Start keeping a daily log of your:

• Heart rate (especially lying vs standing)

• GI symptoms
• Skin reactions (rashes, flushing, itching)
• Neurological issues (brain fog, migraines)
• Sleep, pain, temperature intolerance, and more

➡️ Get the full diagnosis guide, below, as a free download when you subscribe

2. Do a Passive Standing Test at Home (for POTS)

• Lie down for 10 minutes and measure your heart rate.
• Stand up and record your heart rate every minute for 10 minutes.
• An increase of 30+ bpm (or total HR >120 bpm) may indicate POTS.
  Take notes to show your doctor.

3. Find the Right Kind of Provider

Look for:

• Cardiologists or neurologists specializing in dysautonomia
• Allergists/immunologists or functional medicine providers familiar with MCAS
• Nurse practitioners who treat EDS, POTS, and MCAS
• EDS/dysautonomia clinics

📍 Tip: Social media and support groups often have great doctor recs.

4. Bring Documentation to Appointments

Show up prepared:

• Symptom logs
• Heart rate data
• Photos of rashes or visible symptoms
• Family history + past labs

Doctors may take you more seriously when you bring data. It’s unfortunate, but it helps.

5. Understand Diagnostic Challenges

There’s no “one test” for POTS or MCAS.

POTS testing may include:

• Passive standing test
• Tilt table test
• ECG or 24-hour monitor

MCAS testing may include:

• Tryptase, prostaglandins, histamine levels
• Urine methylhistamine, PGD2
• Trial response to medications like antihistamines or mast cell stabilizers

Often, clinical diagnosis is what makes the difference. In my case, none of my blood work was remarkable; but I had all of the symptoms.

💌 Free Download: Diagnosis Guide PDF

I created this resource for those, like me, who have had to fight to be heard.
It includes:

• Symptom tracking tips
• Printable passive stand test
• Diagnosis checklist
• What to say at appointments
• And more…

Just enter your email and I’ll send it your way. You’ll also receive occasional updates with resources and support for navigating chronic illness, mental health, and healing.

You Are Not Imagining This

So many of us live with symptoms for years before finding the words—let alone the diagnosis—that explains what’s happening. If this sounds like you, please hear me:

You are not overreacting.
You are not alone.
You are not imagining this.

Keep trusting yourself. Keep asking questions. Keep seeking answers.

I’m with you.

—Dr. Christina Hibbert
Psychologist | Chronic Illness Advocate | Breast Cancer Warrior

Don't forget to get your free POTS & MCAS Diagnosis Guide Download!

Share your experiences with getting diagnosed, below!