Porphyria, Acute

• • Acute porphyrias are a group of inherited diseased that arise from errors in heme biosynthesis leading to overproduction of a porphyrin species

  • Acute intermittent porphyria has the most serious consequences and is the form in which patients commonly manifest an acute abdomen

  • Classic patient is a young woman (teens to early 20s) with an unexplained abdominal crisis

  • Abdominal symptoms are thought to be due to acute (abdominal visceral) autonomic dysfunction

  • Acute peripheral or CNS dysfunction

  • Recurrent psychiatric illnesses

  • Hyponatremia

  • Porphobilinogen in the urine during acute attacks

Epidemiology

• • Acute intermittent porphyria is inherited in an autosomal dominant fashion, although the trait remains clinically silent in the majority of carriers

  • Acquired forms of porphyria disorders may be caused by chemicals, drugs, or heavy metals such as lead

  • Acute porphyria may be precipitated by starvation or certain drugs, classically the barbiturates, anticonvulsants, and sulfonamides

Symptoms and Signs

• • Absence of fever

  • Intermittent abdominal pain of varying severity, from mild colic to an acute abdomen

  • Central, peripheral, or autonomic neuropathy which can be profound including: respiratory paralysis, quadriplegia, or seizures

  • Recurrent psychiatric illness

Laboratory Findings

• • Absence of leukocytosis

  • Often a profound hyponatremia secondary to syndrome of inappropriate antidiuretic hormone (SIADH)

  • Increased amount of porphobilinogen in the urine (freshly voided specimen may turn dark when exposed to bright light and room air)

Imaging Findings

• • No radiographic abnormalities

• • The differential diagnosis is that of an acute abdomen:

  • -Appendicitis

    -Perforated gastroduodenal ulcers

    -Diverticulitis

    -Gangrenous cholecystitis

    -Acute salpingitis

    -Nonvascular small bowel perforation

    -Large bowel perforation

    -Mesenteric ischemia

    -Acute necrotizing pancreatitis

    -Bowel obstruction

    -Incarcerated hernia

    -Ureteral or renal colic

    -Others

Rule Out

• • Surgical abdomen

• • CBC

  • Basic chemistries

  • Amylase and lipase

  • UA

  • Urine porphobilinogen

  • Abdominal pelvic CT scan with IV and PO contrast helpful in ruling out surgical etiology

When to Admit

• • Patients with an episode of acute intermittent porphyria should be admitted for supportive medical management until attack resolves

When to Refer

• • Acute porphyria attacks are best managed by hematologists

  • ICU care may be indicated based on severity of attack and associated neuropathy

• • IV glucose (a minimum of 300 g carbohydrate per day)

  • Hematin administration

  • Analgesics

  • Correction of hyponatremia

  • Treatment as indicated for associated neuropathy

Surgery

• • Laparoscopy

Indications

• • In confusing cases, a diagnostic laparoscopy may exclude an abdominal surgical catastrophe

Medications

• • Carbohydrates

  • Hematin

Complications

• • Most ...