Evaluating the Prevalence of Acute Hepatic Porphyria in Postural Tachycardia Syndrome

January 21, 2026 updated by: Cyndya Shibao, MD, Vanderbilt University Medical Center

Estimating the Frequency and Neuro-Hormonal Characteristics of Acute Hepatic Porphyria in Postural Tachycardia Syndrome

Postural Tachycardia Syndrome (POTS) is the most common autonomic disorder and is estimated to affect 3,000,000 individuals in the United States, with 80-85% of patients being women. The condition is characterized by a rapid increase in heart rate (HR) that occurs on standing, and chronic symptoms of cerebral hypoperfusion leading to lightheadedness, dizziness, and blurred vision.

The acute hepatic porphyrias(AHP)are among the diseases that present with autonomic cardiovascular(tachycardia)and neurovisceral symptoms (abdominal pain) among others; they present with acute exacerbations Given that there is available treatment for AHP that change the natural progression of the disease, study focuses to investigate the occurrence of AHP in POTS and determine the clinical and neuro-hormonal characteristic of the POTS subgroup that will likely benefit from AHP screening.

This study has one visit that involves, answering some questionnaires, coming to the lab for blood work, genetic testing, and some autonomic function tests. About 50 people will take part in this study.

Study Overview

Status

Active, not recruiting

Conditions

Intervention / Treatment

Detailed Description

Postural Tachycardia Syndrome (POTS) affects ~3 million young women in the United States.(1)These patients have a low quality of life because of chronic presyncopal symptoms, and orthostatic tachycardia that occur while standing. POTS can be the initial presentation of an underlying illness. A substantial group of patients with POTS reported that their symptoms started after an acute illness, surgical intervention, substantial weight loss or after ingesting certain medications. These are the same triggers for acute AHP attacks.

Furthermore, the demographic characteristics of AHP overlaps with that of POTS. AHP also affects primarily young women, in their reproductive age. POTS can have a diverse presentation, some patients present with axonal autonomic neuropathy, and severe gastrointestinal symptoms which are co-morbid conditions also present in chronic AHP.

It is within this context that investigators propose to assess the occurrence of AHP in the general POTS population, identify its clinical presentation and neuro-hormonal characteristics.

Rationale and Endpoints:

  1. To evaluate occurrence of AHPs in POTS patients with autonomic and neurovisceral symptoms referred to a National Referral Center for the treatment of Autonomic Disorder.
  2. To determine the autonomic and neuro-hormonal characteristics of AHP-POTS patients compared with POTS patients

Enrollment:

This is a cross-sectional study conducted at the Vanderbilt Autonomic Dysfunction Clinic (ADC). Investigators plan to enroll patients with suspicions of POTS who are referred to the ADC for evaluation and diagnosis.

Study visit:

Single study visit.

Participants will be asked to complete an autonomic symptoms assessment questionnaire (COMPASS 31), and quality of life EQ-5D.

The following laboratory analyses will be performed:

Blood: CBC, CMP, Iron studies (Ferritin and iron studies) Urine PBG, ALA and porphyrins in a spot urine sample with results normalized to urine creatinine.

Genetic testing (Acute hepatic porphyria panel) .

Autonomic function test.

Supine and Standing plasma norepinephrine will be obtained for evaluation of neuro-hormonal changes during orthostasis.

Statistical Analyses

This is a pilot study that will estimate the occurrence of AHPs in POTS patients referred to a National Referral Center for the Treatment of Autonomic Disorders. There is no data available on the prevalence of AHPs in POTS. The prevalence of AHP is one in 6,000 in whites. [ref. Hepatol commun 2019 feb 3(2): 193-206] Given that there are overlapping of symptoms between AHP and POTS, expected that AHP would be overrepresented in POTS patients. The plan is to enroll 50 POTS patients in this pilot study.

Data Analysis Plan:

Standard graphing and screening techniques will be used, to detect outliers and to ensure data accuracy. Continuous endpoints will be assessed for normality. If normality is violated, data transformation will be applied or non-parametric analysis methods will be considered. Investigators will provide summary statistics for both continuous and categorical variables by subject groups (POTS and AHP-POTS). All hypotheses will be tested, at the level of α=0.05. SPSS (version 23.0, SPSS, Chicago, IL) will be used and the open-source statistical package R (R Core Team, 2019 for analyses.

Study Type

Observational

Enrollment (Actual)

70

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Tennessee
      • Nashville, Tennessee, United States, 37232
        • Vanderbilt University Medical Center

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 65 years (Adult, Older Adult)

Accepts Healthy Volunteers

N/A

Sampling Method

Non-Probability Sample

Study Population

Postural Tachycardia Syndrome

Description

Inclusion Criteria

  1. Age 18 - 65 years
  2. Individuals having an established diagnosis of POTS defined as the presence of presyncopal symptoms for more than 6 months and orthostatic tachycardia (>30 bpm increase in HR within 10 min after assuming upright position)
  3. The present of one of the following criteria:

3.1 Family history of acute hepatic porphyria 3.2 Unexplained recurrent (more than one), prolonged (>24 hours) episode of severe, diffuse (poorly localized) abdominal pain AND at least TWO of the following:

  • Red to brownish urine.
  • Blistering skin lesions on sun-exposed areas.
  • Peripheral nervous system manifestations occurring around the time of abdominal pain (i.e., motor neuropathy (paresis), sensory neuropathy (numbness, tingling, limb pain).
  • Central nervous system manifestations occurring around the time of abdominal pain (i.e. confusion, anxiety, seizures, hallucinations).
  • Autonomic nervous system manifestations occurring around the time of abdominal pain (i.e. hyponatremia(Na<lower limit of normal)), tachycardia, hypertension, nausea and vomiting, constipation).

Exclusion Criteria

  1. Pregnant or breastfeeding women
  2. type 2 diabetes mellitus
  3. History of alcohol or drug abuse
  4. Inability to provide informed consent or comply with protocol

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Observational Models: Case-Only
  • Time Perspectives: Cross-Sectional

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
AHP Case ascertainment in POTS patients
Time Frame: During the intervention
Evaluating the Prevalence of Acute Hepatic Porphyria in Postural Tachycardia Syndrome
During the intervention

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Vanderbilt University Medical Center

Investigators

  • Principal Investigator: Cyndya Shibao, M.D, Vanderbilt University Medical Center

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

January 19, 2022

Primary Completion (Actual)

December 30, 2024

Study Completion (Estimated)

June 30, 2026

Study Registration Dates

First Submitted

April 8, 2022

First Submitted That Met QC Criteria

April 21, 2022

First Posted (Actual)

April 25, 2022

Study Record Updates

Last Update Posted (Actual)

January 23, 2026

Last Update Submitted That Met QC Criteria

January 21, 2026

Last Verified

January 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 210724

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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