Porphyrias
Acute Intermittent Porphyria (AIP)
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Porphyria Cutanea Tarda (PCT)
Tuberous Sclerosis
Papillary Thyroid Carcinoma
Acute Myelogenous Leukemia (AML)
Acute-sign In-mitten Poor-fairy
Acute intermittent porphyria is caused by an autosomal-dominant mutation in porphobilinogen deaminase, a key enzyme in the heme synthesis pathway. When porphobilinogen deaminase is inhibited, serum porphobilinogen and Delta-ALA as well as urinary porphyrins build up. AIP attacks occur intermittently and are precipitated by cytochrome P450 inducers, alcohol and starvation. Symptoms may include severe abdominal pain, port wine-colored urine, polyneuropathy and CNS symptoms, as well as psychiatric disturbances. Treatment for AIP flares involves hemin and glucose; two inhibitors of the heme synthesis pathway. Patients should avoid known triggers of AIP flares to prevent symptoms.
Acute intermittent porphyria is inherited in an autosomal-dominant pattern. Therefore, patients only need one mutated gene to inherit the disease.
Inhibited Porphobilinogen Deaminase
Inhibiting-chains on Poor-fairy-babies and Dog-ammo
In acute intermittent porphyria, patients inherit an inhibiting mutation in porphobilinogen deaminase, which converts porphobilinogen into hydroxymethylbilane. In contrast, uroporphyrinogen decarboxylase converts uroporphyrinogen III to coproporphyrinogen III, and is the enzyme mutated in porphyria cutanea tarda.
Increased Serum Porphobilinogen
Up-arrow Poor-fairy-babies
Because porphobilinogen deaminase is inhibited, serum porphobilinogen and delta-ALA build up, as they are synthesized upstream from porphobilinogen deaminase. Urinary porphyrins are also increased, as they spill from the blood to the urine.
Increased Serum Delta-ALA
Up-arrow Delta-Ala
Increased Urinary Porphyrin Precursors
Up-arrow Urinal Poor-fairy
Because porphobilinogen deaminase is inhibited, serum porphobilinogen and delta-ALA build up, as they are synthesized upstream from porphobilinogen deaminase. Urinary delta-ALA and porphobilinogen are also increased, as they spill from the blood to the urine.
Precipitated By P450 Inducers
Pea-450 Inducer-rocket
Patients with acute intermittent porphyria have symptom flares precipitated by various triggers such as cytochrome P450 inducers, alcohol and starvation. Symptoms may include severe abdominal pain, port wine-colored urine, polyneuropathy and CNS symptoms and psychiatric disturbances.
Painful Abdomen
Pain-bolt in Abdomen
Colicky epigastric abdominal pain is typically the presenting sign of an AIP flare. It lasts for several days and is often associated with nausea, vomiting and constipation.
Polly-nerve
During attacks, patients may experience polyneuropathy and other neurological symptoms; such as ascending weakness, seizures and cortical blindness.
Psychological Disturbances
Psycho in a straight-jacket
Patients may experience psychological disturbances such as depression during attacks. They are also at increased risk for certain psychiatric diseases such as bipolar disorder and schizophrenia.
Port Wine-Colored Urine
Port-wine
During flares, patients may have port wine-colored urine; initially the urine is colorless, but exposure to light causes the urine to change its color.
Glucose and Hemin
Glue-bottle and Heme-man
Glucose and hemin are the mainstays of treatment for AIP attacks. Hemin is a heme-containing porphyrin that comes as an IV solution. Both glucose and hemin inhibit ALA synthase, which is the first step in the heme synthesis pathway. By administering these two inhibitors, porphyrins are unable to build up and cause the classic symptoms of an AIP attack.
Avoid Triggers
Avoid-sign with Trigger
Acute intermittent porphyria is triggered by alcohol, starvation and cytochrome P450-inducing drugs including barbiturates, carbamazepine and rifampin. Therefore, patients should avoid these to prevent disease symptoms.
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