delta-Aminolevulinic acid dehydratase deficiency porphyria (ADP) with syndrome of inappropriate secretion of antidiuretic hormone (SIADH) in a 69-year-old woman.

delta-Aminolevulinic acid dehydratase deficiency porphyria (ALAD porphyria, ADP) with syndrome of inappropriate secretion of antidiuretic hormone (SIADH) in a 69-year-old woman is reported. The patient was admitted to our hospital complaining of slight cough with low-grade fever, and treated with piperacillin sodium, resulting in complete resolution of the symptoms, following a diagnosis of bronchopneumonia. Thereafter, however, she began to complain of vomiting, abdominal pain, facial numbness and paresis of the extremities with gait disturbance, and became comatose with hyponatremia (serum Na concentration 119 mEq/L) in a few days. Laboratory tests revealed an antidiuretic hormone (ADH) level of 13.5 pg/mL, plasma osmolality 218 mOsm/KgH2O, urinary osmolality 429 mOsm/KgH20, urinary Na concentration > 20 mEq/L, and no abnormalities of thyroid, adrenal or renal function. Neither edema nor dehydration was evident. These data indicated the presence of SIADH. No abnormalities suggestive of malignant or infectious diseases such as lung cancer, pneumonia and Guillain-Barré syndrome were evident from laboratory and roentgenographic findings. As the cause of SIADH, therefore, porphyria was suspected. Metabolites and activities of enzymes in the heme biosynthetic pathway were examined, and very low activity of delta-aminolevulinic acid dehydratase (ALA-D) (0.14 mumol PBG/mL RBC/h) was found. The patient was neither an alcoholic nor a heavy smoker, and she had no past history of heavy metal intoxication, photosensitivity or tyrosinemia. On the basis of these data and clinical features, she was diagnosed as having ADP. We consider this to be the first case of ADP reported in Japan.