The Porphyrias

The porphyrias are a group of (mostly) hereditary conditions that cause a disruption in the body’s production of the heme molecule (used for haemoglobin).  This is usually due to an enzyme deficiency of some sort.  The result is a build up of nephrotoxic precursors.  (One precursor type is porphyrin which isn’t nephrotoxic but causes photosensitivity of the skin).

They can be acute or chronic.  Acute attacks tend to present with abdominal pain, D&V, mental disorders, photosensitivity and skin problems, and peripheral neuropathy (usually distal weakness and pain).  Chronic forms tend to also cause systemic problems e.g. liver dysfunction.

The porphyrin pathway and what can go wrong where.

There are lots of different types of porphyrias (see image), but the management for them is largely the same: a high carbohydrate diet and heme supplementation, as well as avoiding the use of drugs that are broken down by the same pathway (mainly barbiturates, anticonvulsants, progestins, and rifampin).


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