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PubMed This is a summary of 20 peer-reviewed journal articles Updated
Psychiatry

Symptoms and the Biology of Porphyria

At a Glance

Porphyria symptoms stem from a blockage in the body's heme-making process, which causes toxic chemicals to build up. This buildup attacks the nervous system, causing severe abdominal pain in acute hepatic porphyria, or damages the skin, causing extreme sun sensitivity in cutaneous porphyrias.

Understanding why your body is reacting this way requires looking at a specialized “assembly line” inside your cells called the heme biosynthesis pathway. This pathway is responsible for making heme, the substance that allows your red blood cells to carry oxygen and helps your liver break down toxins [1][2].

The Biological “Assembly Line”

Think of your body’s process for making heme as an eight-station assembly line. Each station has a specific worker (an enzyme) that modifies a chemical and passes it to the next station.

  • The Bottleneck: In porphyria, one of these “workers” is missing or moving too slowly [1].
  • The Pile-Up: Because the assembly line is blocked, the raw materials from the previous stations begin to pile up. These materials, called precursors (like ALA and PBG) or porphyrins, are toxic when they reach high levels [3][4].
  • The Damage: Depending on which station is blocked, these toxins either attack your nervous system (causing acute attacks) or travel to your skin (causing sun sensitivity) [2][5].

Acute Hepatic Porphyria (AHP): The “Great Masquerader”

AHP is known as the “great masquerader” because its symptoms look like many other common emergencies. An acute attack is a medical crisis caused by a massive buildup of neurotoxic precursors [4][6].

Classic Symptoms of an Attack:

  • Severe Abdominal Pain: Usually intense, diffuse, and “deep” in the belly, but unlike an infection, it occurs without a fever or an elevated white blood cell count [7][8].
  • Autonomic Issues: Nausea, vomiting, severe constipation, and a racing heart rate (tachycardia) [9].
  • Muscle and Nerve Problems: You may experience profound muscle weakness, numbness, or even seizures [10][11].
  • Neuropsychiatric Symptoms: Intense anxiety, confusion, or “brain fog” often accompany the physical pain [9][12].

Because these symptoms are so broad, patients are often misdiagnosed with appendicitis, gallbladder attacks, or kidney stones. Tragically, some patients are even referred for psychiatric care because doctors cannot find a visible cause for their extreme pain [9][11].

Cutaneous Porphyrias: Two Ways the Skin Reacts

In cutaneous porphyrias, porphyrins build up in the skin. When sunlight hits these chemicals, they react and cause painful damage [13].

Blistering and Fragility (PCT)

In Porphyria Cutanea Tarda (PCT), the skin becomes incredibly fragile, especially on the back of the hands and face [14].

  • Symptoms: You may notice small, fluid-filled blisters (vesicles) that appear after sun exposure. The skin may peel or tear easily, even with a minor bump, and can leave behind small white bumps (milia) or scars [15][13].

The “Invisible” Burn (EPP)

Erythropoietic Protoporphyria (EPP) is very different because the damage is often internal.

  • Symptoms: Patients feel an excruciating burning, stinging, or itching sensation almost immediately upon sun exposure [16][17].
  • The Challenge: Unlike a sunburn, the skin may look completely normal to an observer—there may be no redness or blisters—despite the patient being in extreme pain [16]. This often leads to misunderstandings with family or doctors who cannot “see” the injury.

Why a Quick Test Matters

During an acute attack, a simple urine test for PBG (porphobilinogen) can confirm the diagnosis [12][18]. Catching the “pile-up” early allows doctors to give treatments that “turn off” the assembly line, stopping the production of toxic chemicals before they cause lasting nerve damage [19][20].

Return to Home

Common questions in this guide

Why does acute hepatic porphyria cause severe abdominal pain?
In acute hepatic porphyria, a blockage in the body's heme production line causes toxic chemicals to build up. These toxins attack the nervous system, leading to intense, deep belly pain that occurs without a fever or elevated white blood cell count.
Why does my skin burn in the sun but look completely normal?
In Erythropoietic Protoporphyria (EPP), sunlight reacts with chemicals built up under the skin, causing excruciating burning, stinging, or itching. Unlike a typical sunburn, this damage is internal and often leaves the skin looking completely normal on the outside.
What does a PBG urine test check for?
A PBG test measures the level of porphobilinogen in your urine during an acute attack. High levels confirm an acute porphyria attack and allow doctors to quickly start treatments that stop the production of toxic chemicals before they cause lasting nerve damage.
How is Porphyria Cutanea Tarda (PCT) different from other skin porphyrias?
PCT causes the skin to become extremely fragile, particularly on sun-exposed areas like the hands and face. It leads to visible fluid-filled blisters, peeling, and scarring after sun exposure, unlike EPP which typically shows no visible outward skin changes.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Could my abdominal pain be related to an enzyme deficiency in my heme pathway rather than a surgical issue like appendicitis?
  2. 2.Is it possible to test my urine for PBG (porphobilinogen) right now while I am having symptoms?
  3. 3.Given that my blood tests don't show a high white cell count or fever, why do you suspect an infection or inflammation?
  4. 4.For my skin symptoms, does the lack of visible blistering (like in EPP) or the presence of fragile blisters (like in PCT) help narrow down which enzyme is affected?
  5. 5.Could any of the medications I was recently prescribed be making these 'assembly line' buildups worse?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (20)
  1. 1

    The Hepatic Porphyrias: Revealing the Complexities of a Rare Disease.

    Balogun O, Nejak-Bowen K

    Seminars in liver disease 2023; (43(4)):446-459 doi:10.1055/s-0043-1776760.

    PMID: 37973028
  2. 2

    Acute Hepatic Porphyria.

    Bissell DM, Wang B

    Journal of clinical and translational hepatology 2015; (3(1)):17-26 doi:10.14218/JCTH.2014.00039.

    PMID: 26357631
  3. 3

    The diagnosis of acute intermittent porphyria combined with seizures: Case report.

    Wang Z, Cheng L, Liang X, et al.

    Medicine 2023; (102(50)):e36167 doi:10.1097/MD.0000000000036167.

    PMID: 38115298
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    The acute hepatic porphyrias.

    Wang B

    Translational gastroenterology and hepatology 2021; (6()):24 doi:10.21037/tgh-2020-01.

    PMID: 33824928
  5. 5

    [Porphyria].

    Stölzel U, Stauch T, Kubisch I

    Der Internist 2021; (62(9)):937-951 doi:10.1007/s00108-021-01066-1.

    PMID: 34185109
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    Neurological Manifestations of Acute Porphyrias.

    Wylie K, Testai FD

    Current neurology and neuroscience reports 2022; (22(7)):355-362 doi:10.1007/s11910-022-01205-7.

    PMID: 35665475
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    EXPLORE: A Prospective, Multinational, Natural History Study of Patients with Acute Hepatic Porphyria with Recurrent Attacks.

    Gouya L, Ventura P, Balwani M, et al.

    Hepatology (Baltimore, Md.) 2020; (71(5)):1546-1558 doi:10.1002/hep.30936.

    PMID: 31512765
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    Therapeutic approach to acute crises of hepatic porphyrias.

    Garrido Montes M, Pertusa Mataix R, Garcia Morillo JS

    Revista clinica espanola 2024; (224(10)):664-669 doi:10.1016/j.rceng.2024.09.004.

    PMID: 39313028
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    Unexpected presentation of acute porphyria.

    Kiew CK, Lam ASEL

    BMJ case reports 2021; (14(6)) doi:10.1136/bcr-2021-241580.

    PMID: 34187794
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    Porphyric encephalopathy in a 15-year-old girl: A case report.

    Dukkipati SS, Terschluse J, Thodeson D, et al.

    SAGE open medical case reports 2025; (13()):2050313X241298532 doi:10.1177/2050313X241298532.

    PMID: 39881736
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    A Case of Acute Intermittent Porphyria Mimicking Guillain-Barré Syndrome.

    Mutluay B, Köksal A, Çelık RGG, Bülbül HH

    Noro psikiyatri arsivi 2019; (56(4)):311-312 doi:10.5152/npa.2017.19474.

    PMID: 31903042
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    Hyponatremia and Abdominal Pain: A Case Report of Acute Hepatic Porphyria.

    Roldão M, Soares Dionísio A, Duarte J, et al.

    Cureus 2026; (18(1)):e101733 doi:10.7759/cureus.101733.

    PMID: 41704990
  13. 13

    Epidemiology of cutaneous porphyria in Israel: a nationwide cohort study.

    Edel Y, Mamet R, Snast I, et al.

    Journal of the European Academy of Dermatology and Venereology : JEADV 2020; (34(1)):184-187 doi:10.1111/jdv.15769.

    PMID: 31264284
  14. 14

    Porphyria cutanea tarda associated with nitrofurantoin: A unique drug reaction.

    Franciosi EB, Amano SU, Scharf MJ

    Dermatologic therapy 2020; (33(6)):e14026 doi:10.1111/dth.14026.

    PMID: 32677740
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    Porphyria cutanea tarda triggered by hepatitis-E virus.

    Hrabak P, Benesova K, Zahorakova D, Bruha R

    Bratislavske lekarske listy 2024; (125(10)):587-588 doi:10.4149/BLL_2024_91.

    PMID: 39344760
  16. 16

    Ultraviolet A phototest positivity is associated with higher free erythrocyte protoporphyrin IX concentration and lower transferrin saturation values in erythropoietic protoporphyria.

    Genovese G, Maronese CA, Moltrasio C, et al.

    Photodermatology, photoimmunology & photomedicine 2022; (38(2)):141-149 doi:10.1111/phpp.12727.

    PMID: 34420239
  17. 17

    Erythropoietic protoporphyria in pregnancy.

    Nevins EG, Wijesiriwardana A

    Journal of obstetrics and gynaecology : the journal of the Institute of Obstetrics and Gynaecology 2021; (41(4)):657-658 doi:10.1080/01443615.2020.1777954.

    PMID: 32715814
  18. 18

    Effect of Menstrual Cycle on Acute Intermittent Porphyria.

    Júnior VRS, Lemos VMV, Feitosa IML, et al.

    Child neurology open 2017; (4()):2329048X17736170 doi:10.1177/2329048X17736170.

    PMID: 29094055
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    Therapy Follows Diagnosis: Old and New Approaches for the Treatment of Acute Porphyrias, What We Know and What We Should Know.

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    Diagnostics (Basel, Switzerland) 2022; (12(7)) doi:10.3390/diagnostics12071618.

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    Acute intermittent porphyria, givosiran, and homocysteine.

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    PMID: 34145602

This page is for informational purposes only and does not replace professional medical advice. Always consult your healthcare provider about your specific symptoms and diagnosis.

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