Porphyria Flashcards
What are porphyrias?
Porphyrias are inherited errors of metabolism in which
porphyrins (proteins essential for oxygen transport among other
functions) are overproduced.
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 305.
What is considered to be the most vital porphyrin
produced in the body?
Heme is considered to be the most vital porphyrin. It combines
with proteins to form hemoglobin and the cytochrome P-450
isoenzymes.
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 305.
What is the pathophysiologic characteristic that
distinguishes one form of porphyria from another?
There are eight major steps in the formation of heme. Each
step requires a specific enzyme to produce the next chemical in
the chain reaction. Each form of porphyria is defined by a
deficiency in the enzyme that accomplishes a specific step.
Depending upon the enzyme that is lacking, there is an
accumulation in the chemical components that lead up to it,
similar to cars being backed up on a blocked freeway. The
specific chemical components that accumulate cause different
disease characteristics to appear.
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 305-306.
What is the most common type of porphyria? What
is the most common type of ACUTE porphyria?
Porphyria cutanea tarda is the most common form of porphyria.
It usually appears as photosensitivity in males over the age of
35 and is not stimulated by the administration of any drugs, nor
does it exhibit any forms of neurotoxicity. Acute intermittent
porphyria is the most common acute form of porphyria. It
produces the most serious symptoms such as hypertension,
renal dysfunction, and CNS symptoms and can be precipitated
by the administration of certain drugs.
Stoelting RK, Dierdorf SF. Anesthesia & Co-Existing Diseases.
5th ed. New York, NY: Churchill-Livingston; 2008: 315.
What are common symptoms of an acute porphyric
attack?
Severe abdominal pain, nausea, diarrhea, dark urine, seizures,
cranial nerve deficits, peripheral neuropathy, hypertension,
skeletal muscle weakness, and electrolyte disorders.
Fleisher LA. Anesthesia and Uncommon Diseases. 6th ed.
Philadelphia, PA: Elsevier Saunders; 2012: 182.
Can patients with acute intermittent porphyria
undergo regional anesthesia?
Yes, there is no evidence that any regional technique or local
anesthetic has precipitated an acute porphyric attack.
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 309.
How should an acute porphyric attack be treated?
Avoiding any other precipitating factors is key, keeping the
patient warm (cold may precipitate an attack), and administering
intravenous glucose can shorten the length of an attack. If an
attack occurs in the operating room, benzodiazepines should be
administered to help alleviate symptoms. Propofol is another
anesthetic agent that can be administered until other measures
can be taken to relieve the patient’s condition.
Fleisher LA. Anesthesia and Uncommon Diseases. 6th ed.
Philadelphia, PA: Elsevier Saunders; 2012: 183-184.
How does NPO time relate to patients with acute
intermittent porphyria?
Fasting has been identified as a precipitating factor for AIP. As
such, prolonged NPO times should be avoided and the
administration of a glucose-saline solution during the NPO time
should be considered.
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 306-307.
What anesthesia-related drugs should definitely be
avoided in patients with porphyria?
An easy mnemonic to remember which anesthesia-related
drugs should be avoided in patients with acute intermittent
porphyria is “a patient with porphyria should avoid being a
KEPT MAN” for Ketorolac, Etomidate, Pentazocine, Thiopental,
Methohexital And Nifidepine”.
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 308.
