These two patients support the key role for IGF-I in intrauterine and postnatal growth. The different phenotypes of these and earlier described patients may be associated with variability in IGF-I signaling. The degree of intrauterine growth retardation may be partially determined by the presence or absence of maternal IGF-I resistance.

Severe salt wasting can be prevented by neonatal screening. The prevalence, specificity, and sensitivity allowed addition of screening for CAH to the routinely performed national neonatal screening program.

Congenital adrenal hyperplasia (CAH) is well suited for newborn screening, as it is a common and potentially fatal disease which can be easily diagnosed by a simple hormonal measurement in blood. Moreover, early recognition and treatment can prevent severe salt wasting, dehydration and death and shorten the time of male sex assignment in virilised females.

Aims: To evaluate growth from diagnosis until final height (FH) in 21-hydroxylase deficiency patients. Methods: A retrospective longitudinal study was performed. Only patients treated with hydrocortisone and fludrocortisone (in case of salt wasting) were evaluated. This resulted in a sample of 34 (21 male, 13 female) salt wasting patients (SW) and 26 (13 male, 13 female) non-salt wasting patients (NSW). Auxological data were compared to recent Dutch reference values. Results: In the first three months of life, the mean length SDS decreased to −1.50, probably because of the high average glucocorticoid dose (40 mg/m 2 /day). FH corrected for target height (FH corr TH) was −1.25 and −1.27 SDS in females and males, respectively. Patients treated with salt supplements during the first year, had a better FH corr TH (−0.83 SDS). In NSW patients, FH corr TH was −0.96 and −1.51 SDS in females and males, respectively. In SW and NSW, age at onset of puberty was within normal limits, but bone age was advanced. Mean pubertal height gain was reduced in males. Body mass index was only increased in NSW females. Conclusion: In SW, loss of final height potential might be a result of glucocorticoid excess in the first three months and sodium depletion during infancy. In NSW, loss of FH potential was caused by the delay in diagnosis. In SW and NSW, the advanced bone age at onset of puberty (undertreatment in prebertal years) resulted in loss of height gain during puberty. The effect of intensive sodium chloride support in early infancy should be examined prospectively. Neonatal screening is required if the height prognosis in NSW patients is to be improved.

This study demonstrates that GA is a better predictor of 17OHP in newborns and will result in greater specificity than BW despite the fact that the determination of GA might be less reliable than BW.