Interpretation of 17-hydroxyprogesterone (17-OHP) in suspected congenital adrenal hyperplasia (CAH) requires understanding that elevated 17-OHP levels are a key biochemical marker indicating 21-hydroxylase deficiency, the most common cause of CAH.
In a suspected case, a significantly raised basal 17-OHP level strongly supports the diagnosis of classic CAH, especially if levels exceed the established diagnostic thresholds used in UK clinical practice NICE NG243. However, borderline or mildly elevated basal 17-OHP levels may require an ACTH stimulation test to clarify diagnosis, as stimulated 17-OHP levels provide greater sensitivity and specificity for detecting partial enzyme deficiency or non-classic CAH NICE NG243.
It is important to interpret 17-OHP results in the clinical context, considering age, sex, and timing of sample collection (ideally morning fasting samples), as physiological variations can affect levels NICE NG243. Additionally, recent literature emphasizes that steroid profiling, including 17-OHP alongside other steroid precursors, can improve diagnostic accuracy and help differentiate CAH subtypes Sarafoglou et al. 2023Bacila et al. 2024.
In summary, a raised 17-OHP level is a critical diagnostic biomarker for CAH, but borderline results should prompt further dynamic testing and steroid profiling to confirm diagnosis and guide management NICE NG243 Sarafoglou et al. 2023Bacila et al. 2024.