After basal levels have been measured, confirmation is done by administering ACTH, and comparing 17-OHP pre and post test. 17-OHP levels over 10 ng/mL at the 60th minute post stimulation is considered diagnostic for LOCAH. Androgen backdoor pathway
In 21-hydroxylase deficiency, especially in mild cases (LOCAH), the androgen "backdoor" pathway may be the reason of androgen excess. This backdoor pathway is not always considered in the clinical evaluation of patients with hyperandrogenism conditions such as LOCAH and may be a source of diagnostic pitfalls and confusion. One case study demonstrated the importance of considering serum 5α-dihydrotestosterone (DHT) levels and the androgen backdoor pathway in a LOCAH diagnosis that would have not been apparent from testosterone levels alone. 11β-Hydroxylase deficiency
The activity of 11β-hydroxylase can be determined by observing the basal  11-deoxycortisol level. A level over 10 ng/mL, indicates followup with ACTH stimulation test. The 60th minute post-stimulation 11-deoxycortisol levels higher than 18 ng/mL are diagnostic of LOCAH. 3β-Hydroxysteroid dehydrogenase deficiency
The activity of 3β-hydroxysteroid dehydrogenase can be determined by observing the basal 17α-hydroxypregnenolone level. A level above 30 ng/mL and 17α-hydroxypregnenolone/cortisol ratio above 10 SD are diagnostic of LOCAH. Management
Management and treatment of LOCAH is case specific and the application of glucocorticoid treatment is not standard as it is in classic CAH. LOCAH is not a life-threatening medical condition and the risks of treatment given prenatally or to asymptomatic children outweigh potential benefits.
Late onset congenital adrenal hyperplasia (LOCAH), also known as nonclassic congenital adrenal hyperplasia (NCCAH or NCAH), is a milder form of congenital adrenal hyperplasia (CAH), a group of autosomal recessive disorders characterized by impaired cortisol synthesis that leads to variable degrees of postnatal androgen excess.The causes of LOCAH are the same as of classic CAH, and in the majority of the cases are the mutations in the CYP21A2 gene resulting in corresponding activity changes in the associated P450c21 (21-hydroxylase) enzyme which ultimately leads to excessive androgen production. Other causes, albeit less frequent, are mutations in genes affecting other enzymes involved in steroid metabolism, like 11β-hydroxylase or 3β-hydroxysteroid dehydrogenase. It has a prevalence between 0.1% and 2% depending on population, and is one of the most common autosomal recessive genetic diseases in humans. The pathophysiology is complex and not all individuals are symptomatic. Presentation
Patients with LOCAH usually present with signs of hyperandrogenism, rather than of glucocorticoid deficiency, a condition characterized by inadequate cortisol production. Cortisol synthesis impairment is mild but clinically silent. LOCAH patients usually have the same baseline but lower peak cortisol levels comparing to healthy controls.