Congenital adrenal hyperplasia (CAH) is a rare genetic disorder that affects the adrenal glands and can cause various health problems. While the prevalence of CAH in newborns is well-known, data on patients diagnosed later in life is limited.
A recent study conducted in Denmark and published in The Lancet Regional Health aimed to provide insights into diagnosing and managing Congenital adrenal hyperplasia (CAH). This rare genetic disorder affects the adrenal glands and can cause various health problems.
CAH refers to a group of autosomal recessive inherited disorders characterized by disturbed steroid hormone synthesis due to enzymatic deficiency at specific steps in the steroidogenic cascade. The most frequent form of CAH is a 21-hydroxylase deficiency (21-OHD), accounting for up to 99% of all CAH cases.
The study presents the prevalence of females and males with CAH in Denmark for almost 100 years, along with estimates of incidence and age at diagnosis for CAH combined and according to subtype. The study found that the combined prevalence of CAH is higher in Denmark than previously reported in other countries with similar healthcare systems because of a higher apparent prevalence of simple virilizing (SV) and non-classic (NC) CAH.
The incidence of females and males with NC CAH increased during the study, contributing to clear changes in the proportion of CAH subtypes. The study also observed a marked rise in the prevalence and incidence of both females and males with salt-wasting (SW) CAH during the 1960s, likely due to the introduction of hydrocortisone treatment. The prevalence of males with SV and NC CAH did not increase until a couple of decades later, probably reflecting less clinical awareness of males with these conditions in the past due to the standard genital presentation.
The study also acknowledges that classifying a spectrum disorder like CAH into three groups will always be subject to debate. Additionally, the study mentions that screening for CAH has been implemented in neonatal screening programs in several countries worldwide to prevent a salt-wasting adrenal crisis and reduce mortality. However, NC CAH is not a target disease of the screening.
The clinical presentation of CAH is closely related to the severity of the enzymatic deficiency, resulting in a continuum of phenotypes. The most severe form is Salt-wasting (SW) CAH, which can cause fatal outcomes within a few weeks after birth if left untreated. To prevent this, screening for CAH has been implemented in neonatal screening programs worldwide. It has been shown to effectively reduce the time to diagnosis and the number of salt-wasting severe crises.
Simple-virilizing (SV) CAH is diagnosed in subjects with just slight residual 21-OH activity (1–5%), resulting in aldosterone synthesis adequate to avoid profound neonatal salt loss. However, cortisol deficiency with accompanying androgen excess still necessitates glucocorticoid treatment to avoid acute adrenal insufficiency and further virilization of females.
The less severe form is Non-classic (NC) CAH, where patients typically have sufficient residual enzyme activity (30–50%) to present with normal basal levels of cortisol and aldosterone but with elevated adrenal androgen levels. NC CAH is typically ascertained in late childhood or young adulthood due to symptoms of androgen excess.
The nationwide population-based study conducted in Denmark aimed to identify the entire Danish CAH cohort and describe trends in incidence, prevalence, and age at diagnosis – combined as well as according to subtype and sex. The findings of this study provide valuable insights into the diagnosis and management of CAH, which can inform clinical practice and improve patient outcomes.
Valid data on the incidence and prevalence of these forms of CAH are not easy to obtain, nor are data regarding age at diagnosis. To our knowledge, only one Swedish study has to date reported population-based data, including patients diagnosed at screening and clinically and late-diagnosed patients.