4
 
 
Symptoms in Acute Intermittent Porphyria

 
 
 
     
 

* The expression of neurological and other symptoms depends upon lifestyle and exposure to precipitating factors. Early examples of AIP were revealed as a response to new drugs:


- - - - - initially the hypnotic Sulfonal
- - - - - later barbiturates
- - - - - and subsequently many other drugs
-- - - - -including alcohol
- - - - - and sundry organic compounds.8

  
     
  * Some steroid metabolites precipitate attacks, and endogenous changes may account for some crises at puberty and the earlier onset with females.  
     
  * Other exacerbating factors include infections and malnutrition. Low-carbohydrate and low-protein diets are especially detrimental9 and fasting can precipitate an attack of porphyria.10 A study in Scotland indicated an association between smoking (nicotine is metabolized via cytochrome P450) and the induction of repeated attacks in patients already diagnosed with AIP.11 Even an excess of coffee may be a problem because caffeine is also porphyrogenic.8  
     
  * The unpredictable nature of the disease with respect to both onset of crises and outcome makes an acute attack of AIP particularly treacherous. It can be one of the most terrifying experiences imaginable. Patients can become almost completely paralyzed in severe cases. They are unable to breathe, swallow or communicate properly, yet remain conscious for some time, all the while suffering pain, being aware of their plight, and wondering if it will ever end. The most common cause of death from AIP is respiratory paralysis.  
     
  * A retrospective study12 examined the cumulative survival for a group of 136 patients (from a region of the United States) who were hospitalized for porphyric attacks between 1940 and 1988. The proportionate increase in mortality due to symptomatic AIP was 3.2-fold compared to an age-matched hypothetical population experiencing USA 1970 Census death rates. Most of deaths occurred during the initial porphyric attack (20% of deaths) or a subsequent attack (38% of deaths). Suicide was also common (five deaths).  
     
  The biochemical pathway to heme.  
  Almost any cell in the human body can engage in synthesis of heme. It is not only vital to hemoglobin but also for the cytochromes involved in so many aspects of metabolism.  
     
  * The organ of primary concern in AIP is the liver, where two thirds of the heme that is produced is incorporated into the various types of cytochrome P450. An even larger proportion attains during the induction of P450's, which attends the liver's encounter with xenobiotics.  
     
  * The biochemical pathway to heme consists of eight enzymes and an exquisite control mechanism.  
       
   
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