[Epidemiologic study of dwarfism in Niigata Prefecture]

Epidemiologic study on dwarfism (height under "Mean-2.58 S.D") was performed in elementary schools and junior high schools in Niigata Prefecture. Results were as follows: Prevalences of dwarfism were 0.17% in elementary schools (age at 6-12 y.o.), 0.26% in junior high schools (12-15 y.o.), and 0.20% in all (690 dwarf students of 339,854 students). Prevalences in female was 1.3 times as high as that in male. 476 of 690 dwarf students were further examined. 50 (10.5%) of them had pituitary dwarfism and 2 (0.4%) had hypothyroidism. 24 of 50 cases with pituitary dwarfism and one of 2 cases with hypothyroidism were newly diagnosed in this study. One family who seemed to have autosomal-dominant inherited pituitary dwarfism was found in this study. The heights of brothers (11 y and 9 y 6 m) and their mother were under "Mean-4.0 S.D" and they were diagnosed as patients with isolated GH deficiency. The heights of their grandmother and aunt were also under "Mean-4.0 S.D", but they have not been examined. In both brothers and their mother, plasma GH levels didn't respond to iv bolus injection of GRF (1.0 micrograms/kg), and brain CT showed empty sella. Of 476 dwarf students, 249 (52.3%) had constitutional dwarfism, 118 (24.8%) had either constitutional dwarfism or delayed adolescence, 23 (4.8%) had Turner's syndrome (including Noonan's syndrome), and 13 (2.7%) had chondrodysplasia. Dwarf female whose ratios of the maximum response of plasma LH to LHRH/the maximum response of plasma FSH to LHRH were more than 2.0 and dwarf male whose plasma basal level of testosterone were more than 40 ng/ml were expected to become adolescent in the near future. Plasma IGF-I levels determined by RIA with unextracted samples did not clearly differentiate pituitary dwarfism from others.