Clinical features (neurological porphyrias):
General features:
- Acute ascending paralysis with areflexia, affecting VII nerve as well
- Sensory loss may occur “swimming trunk distribution”
- Autonomic neuropathy: tachycardia and orthostatic hypotension
- Confusion, anxiety
- Urine becomes dark on exposure to sunlight.
Subtypes:
- Acute forms: Cause neurological disease and raised ALA
- Acute intermittent porphyria AIP: no cutaneous rash
- Variegate porphyria
- Hereditary coproporphyria: extremely rare
- Non-Acute forms: no neurological disease
- Porphyria cutanea tarda PCT
- Cutaneous hepatic porphyria
- Congenital porphyria
- Erythropoietic protoporphyria EPP
Acute intermittent porphyria AIP:
Screen: 24 hr urinary collection for porphyrin levels
Aminolevulinic acid ALA: high
Porphobilinogen PBG: high
Diagnosis:
RBC enzymes:
Porphobilinogen PBG deaminase: reduced
Delta ALA synthetase: high
Causes neurological symptoms. Note differential diagnosis: Lead poisoning
Treatment:
For crisis: hematin I.V.
Prevention of attacks
Variegate porphyria (South African):
Causes neurological symptoms
Porphyria cutanea tarda PCT:
Urine uroporphyrin I (URO I): high
Stool isocoproporphyrin (ISOCOPRO): high
Does not causes neurological symptoms
Erythropoietic protoporphyria EPP:
Screen: erythrocyte porphyrins
Protoporphyrinogen IX (PROTO IX)
Does not causes neurological symptoms