hEDS, POTS & MCAS Doctor in Seattle, WA: Root-Cause Care for Hypermobility and Dysautonomia

If you have been told your joints are "just flexible," your heart rate spikes are "anxiety," or your allergic reactions are "unexplained," you are not alone, and you are not imagining it. Hypermobile Ehlers-Danlos Syndrome (hEDS), Postural Orthostatic Tachycardia Syndrome (POTS), and Mast Cell Activation Syndrome (MCAS) are three deeply interconnected conditions that frequently travel together, and they are chronically underdiagnosed.

Dr. Katherine Carvlin, ND, is a naturopathic and environmental medicine physician in Seattle, WA who specializes in diagnosing and treating the hEDS-POTS-MCAS trifecta. Practicing at Full Circle Natural Medicine, Dr. Carvlin offers individualized, evidence-informed care that addresses the underlying physiology driving your symptoms, not just the symptoms themselves.

Book an Appointment

Why hEDS, POTS, and MCAS Often Appear Together

These three conditions are not coincidentally linked. Research increasingly shows they share common threads in connective tissue dysfunction, immune dysregulation, and autonomic nervous system instability.

Hypermobile Ehlers-Danlos Syndrome (hEDS) is a heritable connective tissue disorder caused by defects in collagen structure. Because collagen is the primary building block of skin, ligaments, tendons, blood vessel walls, and organ linings, weak or lax connective tissue creates widespread instability throughout the body, far beyond the joints.

Postural Orthostatic Tachycardia Syndrome (POTS) is a form of dysautonomia in which the autonomic nervous system fails to regulate heart rate and blood pressure properly when you move from lying to standing. Lax blood vessel walls (a direct consequence of connective tissue dysfunction) allow blood to pool in the lower body, triggering compensatory heart rate surges, lightheadedness, brain fog, and fatigue.

Mast Cell Activation Syndrome (MCAS) involves mast cells, immune cells found in connective tissue throughout the body, releasing histamine and inflammatory mediators inappropriately. In people with hEDS, poorly supported mast cells sitting in unstable connective tissue may be more prone to triggering. MCAS produces a wide range of seemingly unrelated symptoms including flushing, hives, gut cramping, anaphylaxis-like reactions, brain fog, and chemical sensitivities.

Together, this triad creates a cycle of inflammation, nervous system dysregulation, and structural instability that can be profoundly disabling, and profoundly misunderstood by conventional medicine.

Common Symptoms Across the hEDS-POTS-MCAS Triad

Because these conditions overlap, symptoms span multiple body systems. Patients often spend years collecting diagnoses from different specialists without anyone connecting the picture.

Musculoskeletal & Structural

  • Joint hypermobility, chronic subluxations, or dislocations

  • Widespread muscle pain, tendinopathy,
    or soft tissue injuries that are slow to heal

  • Chronic neck and back instability

  • Poor proprioception and balance difficulties

Autonomic & Cardiovascular

  • Heart rate spikes of 30+ bpm upon standing

  • Dizziness, lightheadedness, or fainting

  • Exercise intolerance and post-exertional malaise

  • Cold hands and feet, temperature dysregulation

  • Palpitations and chest pressure

Immune & Allergic

  • Hives, flushing, or skin reactions with no clear trigger

  • Food sensitivities that seem to multiply over time

  • Anaphylaxis or near-anaphylaxis episodes

  • Reactions to medications, fragrances, or environmental chemicals

  • Histamine intolerance

Neurological & Cognitive

  • Brain fog and memory difficulty

  • Headaches and migraines

  • Neuropathic pain or burning sensations

  • Anxiety and nervous system hyperactivation

  • Sleep disruption and unrefreshing rest

Gastrointestinal

  • Nausea, bloating, and abdominal cramping

  • Slowed gastric motility or gastroparesis

  • SIBO or chronic gut dysbiosis

  • Diarrhea and constipation cycling

Dr. Carvlin's Approach to Hypermobile EDS Treatment

Effective hypermobile EDS treatment requires addressing all three layers of dysfunction simultaneously: the structural, the autonomic, and the immune. Dr. Carvlin builds individualized protocols using functional medicine, environmental medicine, and naturopathic principles.

1. Comprehensive Evaluation & Validation

Your initial consultation is extensive. Dr. Carvlin reviews your full health history, prior diagnoses, medications, environmental exposures, and symptom timeline. Many patients arrive having been dismissed or told their symptoms are psychosomatic. In this practice, your experience is taken seriously from the first conversation.

2. Diagnostic Workup

Confirming hEDS, POTS, and MCAS requires a multi-system assessment. Testing and evaluation may include:

  • Beighton Score & Connective Tissue Exam: Evaluating joint mobility, skin texture, and structural findings consistent with hEDS criteria

  • Orthostatic Vital Signs: Assessing heart rate and blood pressure changes with positional changes to evaluate POTS and dysautonomia

  • Serum & Urine MCAS Markers: Tryptase, histamine, prostaglandins, leukotrienes, chromogranin A, etc… to identify mast cell activation patterns

  • Comprehensive Immune & Inflammatory Panels: Cytokines, complement levels, and immune cell subsets

  • Nutritional & Micronutrient Analysis: Deficiencies in magnesium, B12, iron, and collagen cofactors are common and correctable

  • Gut Function Testing: Evaluating microbiome balance, intestinal permeability, and SIBO, a frequent MCAS trigger

  • Environmental Toxin Screening: Assessing for co-occurring mold illness or biotoxin burden, which frequently worsens MCAS and dysautonomia

3. Stabilizing the Mast Cell Burden

Before addressing structural or autonomic concerns, reducing mast cell reactivity lowers the baseline inflammatory load that drives so many symptoms. Dr. Carvlin combines low-histamine dietary guidance, targeted supplementation (i.e. quercetin, DAO, vitamin C, etc…), and prescription mast cell stabilizers when clinically appropriate.

4. Supporting Autonomic Function & Blood Volume

Improving POTS requires both physiological and lifestyle strategies:

  • Sodium and fluid loading protocols tailored to your tolerance

  • Evidence-based exercise reconditioning starting from a position of safety

  • Compression garment guidance

  • Botanical and nutritional nervous system support

  • IV nutrient therapy (including IV saline and targeted micronutrients) for patients with more severe dysautonomia

5. Connective Tissue & Joint Support

While there is no cure for the underlying collagen defect in hEDS, meaningful stabilization is achievable. Dr. Carvlin addresses:

  • Targeted nutritional support for collagen synthesis (vitamin C, proline, glycine, zinc, manganese)

  • Physical therapy referrals with providers experienced in hEDS-specific stabilization protocols

  • Prolozone and regenerative injection therapy for painful or unstable joints

  • Pain management strategies that minimize medication burden where possible

6. Reducing Environmental & Toxic Triggers

Mold, chemical exposures, and heavy metals can significantly worsen MCAS reactivity and autonomic instability. Dr. Carvlin screens for and addresses environmental co-triggers, a layer of care that is frequently overlooked in conventional hEDS management.

Conditions Treated

In addition to the hEDS-POTS-MCAS trifecta, Dr. Carvlin provides care for conditions that commonly overlap with connective tissue and autonomic dysfunction:

  • Mold Illness & Chronic Inflammatory Response Syndrome (CIRS)

  • Long-COVID & Post-Viral Syndromes

  • Myalgic Encephalomyelitis / Chronic Fatigue Syndrome (ME/CFS)

  • Small Intestinal Bacterial Overgrowth (SIBO) & Complex Gut Dysfunction

  • Lyme Disease & Tick-Borne Co-Infections

  • Autoimmune Conditions & Immune Dysregulation

  • Histamine Intolerance & Food Sensitivities

Why Seattle Patients Choose Dr. Carvlin

hEDS, POTS, and MCAS specialists are rare. Most patients in the Pacific Northwest spend years on waitlists for rheumatology, cardiology, or immunology, receiving care for each condition in isolation, with no one holding the full picture.

Dr. Carvlin holds the full picture. Her training in naturopathic and environmental medicine gives her the tools to evaluate whole-body physiology, identify the interactions between connective tissue dysfunction, immune hyperactivation, and autonomic instability, and build a treatment plan that addresses root causes rather than chasing individual symptoms.

Her practice is warm, collaborative, and unhurried. Patients who have felt dismissed, overwhelmed, or disbelieved by previous providers consistently describe finally feeling heard.

Schedule Your Appointment

Living with hEDS, POTS, or MCAS does not have to mean managing alone. A root-cause evaluation can clarify what is driving your symptoms and open a path toward greater stability, function, and quality of life.

Book Now