Respiratory insufficiency associated with acute hepatic porphyria.

We reported two patients with acute hepatic porphyria with acute respiratory failure. The acute porphyrias are characterized biochemically by increased excretion of porphyrins and porphyrin precursors, ALA and PBG. It has been shown to be due to partial enzyme blockage along the haeme biosynthetic pathway which results in secondary increased ALA synthetase activity. They are characterized clinically by episodes of acute neurological involvement. Neurological manifestations could be related to either a decrease in essential haemeproteins, or to a toxic effect of ALA and PBG. The first patient illustrated a diagnosis of either variegated or hereditary coproporphyria. The second patient had acute intermittent porphyria. Eventhough, the disease is uncommon in Thailand, many drugs can aggravate an acute attack. Thus, we should be careful not to use such drugs in these patients.