Pulmonary arterial hypertension and type-I glycogen-storage disease: the serotonin hypothesis.

A case of pulmonary arterial hypertension in a patient with type-Ia glycogen-storage disease, a rare autosomal recessive disorder caused by a deficiency of glucose-6-phosphatase is reported in this study. It has been suggested that the occurrence of pulmonary arterial hypertension in type-Ia glycogen-storage disease could be due to an abnormal production of vasoconstrictive amines such as serotonin. To test this hypothesis, plasma serotonin concentrations were prospectively measured in 13 patients with type-Ia glycogen-storage disease, one patient with severe pulmonary hypertension and type-Ia glycogen-storage disease, 16 patients displaying severe pulmonary arterial hypertension, and 26 normal healthy controls. Elevated plasma serotonin concentrations were found in patients with either severe pulmonary arterial hypertension (38.8+/-7.3 nmol x L(-1)) or type-Ia glycogen-storage disease (36.8+/-11.5 nmol x L(-1)), as compared with controls (8.8+/-0.6 nmol x L(-1), p<0.001). Plasma serotonin was dramatically elevated in the patient with type-Ia glycogen-storage disease and pulmonary arterial hypertension (113.4 nmol x L(-1)). It is concluded that type-Ia glycogen-storage disease may be another condition in which abnormal handling of serotonin is one event in a multistep process leading to severe pulmonary arterial hypertension.