Porphyria
Stem
A 27-year-old woman, 58 kg, has acute intermittent porphyria; her only attack, at 22, followed a crash diet and a progestin-only pill. She now needs a laparoscopic appendectomy. She has been vomiting and has taken nothing by mouth for 18 hours. Heart rate is 104, blood pressure 128/76, and sodium 134. Her abdominal pain is localized to the right iliac fossa.
Question
How will you anesthetize her?
Ideal answer
HeadlineMy priority is not to precipitate an acute attack; the triggers here are fasting, stress, infection and the wrong drugs.1 Dextrose goes in now.
- Isotonic dextrose-containing infusion now. She has fasted 18 hours and carbohydrate suppresses the pathway; hypotonic fluid can worsen hyponatremia.1,2
- Every drug checked against a porphyria database. Before it goes in, not from memory.2
- Rapid sequence with propofol and succinylcholine, then sevoflurane. Propofol is listed as safe; etomidate, thiopental and ketamine are listed as unsafe.3 Succinylcholine is acceptable.3
- Opioids, acetaminophen, ondansetron, local at the ports. A beta-blocker for tachycardia or hypertension if needed;2 bupivacaine at the port sites;3 warm, calm and analgesed, because stress is itself a trigger.
- Watch for an attack after surgery. New pain out of proportion, tachycardia, hypertension, falling sodium, proximal weakness: then a spot urine for porphobilinogen.4
Breaking down the answer
- Know the defect — AIP is an autosomal dominant partial deficiency of porphobilinogen deaminase (hydroxymethylbilane synthase) in heme synthesis; attacks come when demand for heme is induced.4
- Clear drinks up to two hours — in an elective case, clear carbohydrate drinks until two hours before surgery so she does not arrive in the fasted, attack-prone state.1
- The classic inducers — barbiturates, diazepam, etomidate, ketamine, phenytoin and phenobarbital are listed as unsafe in anesthesia references.1 Cytochrome P450 inducers, including progestogens, sulfonamides, carbamazepine and valproate, also precipitate attacks.2 A database beats memory, and saying so is judgment.
- Regional is fine — both general and neuraxial anesthesia have been used safely; in labor, early epidural placement is reasonable.1 A neuropathy from a prior attack should be documented before any block.
- The full attack picture — abdominal pain with nausea, vomiting and constipation, tachycardia and hypertension, hyponatremia, and proximal paresis that can reach the respiratory muscles.2
Follow-up question
On the first postoperative day she has severe diffuse abdominal pain despite a benign-looking wound, heart rate 132, blood pressure 172/100, sodium 124, and she cannot lift her arms against gravity. What is happening, and how do you treat it?
Follow-up answer
HeadlineAn acute porphyric attack, with proximal weakness that can progress to respiratory failure; I tell the surgeon and the patient and call hematology.
ICU, with regular vital capacity. I send a spot urine for porphobilinogen and ALA4 and stop any drug not on the safe list. Hemin: the label dose is 1 to 4 mg/kg a day for 3 to 14 days, about 200 to 230 mg a day for her at 3.5 to 4 mg/kg, over at least 30 minutes through a large vein because it causes phlebitis.5 Dextrose continues; opioids for pain, a beta-blocker for tachycardia and hypertension, no hypotonic fluid, sodium corrected slowly.2 Strength, sodium and urine output every few hours.
Pitfalls that cost points
- Choosing etomidate for "cardiovascular stability."
- Reaching for a barbiturate or phenytoin for a seizure; correct the sodium and use a listed-safe drug.
- Taking postoperative abdominal pain back to the OR without considering an attack.
- Treating the hyponatremia as simple SIADH with fluid restriction while missing the attack.
Rapid-fire
Q: Which porphyrias do not cause neurovisceral attacks? A: The erythropoietic porphyrias, which present mainly with skin symptoms.1
Q: Why give carbohydrate before hemin in a mild attack? A: The label suggests a period of carbohydrate loading, for example 400 g of glucose a day for 1 to 2 days.5
Q: What is givosiran? A: An siRNA that suppresses hepatic ALAS1, given monthly to prevent frequent attacks.4
Q: Does hemin affect coagulation? A: It has a transient, mild anticoagulant effect, so concurrent anticoagulation is avoided.5
Numbers to know
| Item | Value |
|---|---|
| Hemin dose | 1–4 mg/kg/day for 3–14 days5 |
| Hemin maximum | 6 mg/kg in 24 h5 |
| Hemin infusion | Over ≥30 min, large vein5 |
| Clear carbohydrate fluids | Up to 2 h before surgery1 |
| Inheritance | Autosomal dominant, 50% to each child4 |
Links
- Choosing an induction agent, Rapid sequence induction and full stomach, Hyponatremia and TURP syndrome, PCA and multimodal analgesia, ponv
- American Porphyria Foundation drug safety database
Sources
- 1.Porphyrias: Anesthetic Considerations · OpenAnesthesia · openanesthesia.org
- 2.Acute intermittent porphyria (McMaster Textbook of Internal Medicine) · Empendium · empendium.com
- 3.Drug Safety Database (print version) · American Porphyria Foundation · porphyriafoundation.orgPropofol, sevoflurane, isoflurane, desflurane, vecuronium, bupivacaine 'OK!'; succinylcholine, midazolam, ropivacaine 'OK?'; etomidate, thiopental, ketamine 'BAD!'.
- 4.Acute Intermittent Porphyria · Porphyrias Consortium, NIH Rare Diseases Clinical Research Network · pc.rarediseasesnetwork.org
- 5.Panhematin (hemin for injection) prescribing information · FDA label via Drugs.com · drugs.com
Facts on this page were checked against these sources on Oct 16, 2026. Guidelines change; confirm doses against current institutional protocols.