Difficulties in the diagnosis of congenital adrenal hyperplasia in early infancy: the 11 beta-hydroxylase defect.

Investigations of steroid metabolism in a newborn infant with steroid 11 beta-hydroxylase deficiency are described. Deficiency of this enzyme, like other forms of congenital adrenal hyperplasia (CAH) can be difficult to characterise in the neonatal period. In the first days of life the excretion of cortisol was low but most other hormonal parameters were normal and the major metabolite of 11-deoxycortisol (tetrahydro-S, THS) was not detectable in the urine. Using mass spectrometry, the presence of THS was confirmed in urine collected on the 12th day of life and from this time the excretion rates increased until approximately 300 micrograms were measured in urine on the 27th day of life. A new metabolite of 11-deoxycortisol was tentatively identified as 6 alpha-hydroxy-THS. This steroid is not a significant metabolite in 11 beta-hydroxylase deficiency at other periods of life.