Congenital adrenal hyperplasia (CAH) is a rare cause of hypertension with an incidence in Australia between 1:15 000 and 1:18 000 births.[1] 17-alpha hydroxylase deficiency accounts for only 1% of cases of CAH.[2] The classic presentation in phenotypic females is hypertension, hypokalaemic alkalosis and amenorrhea.[3]
We describe a case of 17-alpha hydroxylase deficiency in an 18-year-old Indigenous female with recurrent presentations of severe symptomatic hypertension and hypokalaemia. This occurred on a background of primary amenorrhoea and minimal secondary sexual development with breast buds only. Investigations revealed a markedly elevated corticotropin (ACTH) and gonadotrophins while cortisol, dehydroepiandrosterone (DHEA) and testosterone levels were low. The urinary steroid profile showed undetectable levels of steroid and androgen metabolites. A karyotype was 46XY. Genetic testing confirmed a homozygous mutation of CYP17A1 resulting in a complete combined deficiency of 17a- hydroxylase /17,20- lyase activity.
Glucorticoid therapy was commenced with rapid normalization of serum potassium and blood pressure.
Data from Western Australia found the incidence of CAH was two and a half times higher in the Indigenous population than the non-Indigenous population.[4] This is the first time that a case of 17-hydroxylase deficiency has been reported in an Indigenous Australian. Its identification in this case has important implications when screening family members for secondary causes of hypertension.