Synthetic glucocorticoids instead of hydrocortisone do not increase mineralocorticoid needs in adult patients with salt wasting congenital adrenal hyperplasia.

It has been postulated that in patients with congenital adrenal hyperplasia (CAH) with salt wasting (SW), fludrocortisone needs might be higher in those on synthetic glucocorticoid replacement therapy in comparison to conventional hydrocortisone due to the lower mineralocorticoid activity. Here we report the results of a cross-sectional single center study comparing mineralocorticoid needs between patients taking synthetic glucocorticoids (S-GC) (N = 24) and those on conventional hydrocortisone (HC) (N = 16). We could show that while both groups took comparable HC-equivalent dosages, there was no significant difference in FC dosage (GC: 0.075 mg; IQR 0.05-0.1; HC: 0.1 mg; IQR 0.05-0.1; p = 0.713). Although there was a trend for higher renin levels in the S-GC group (67.1 µU/ml; IQR 40.5-113.9 vs. 40.4 IQR 14.2-73.1; p = 0.066), this failed to reach significance. With regard to blood pressure, those taking S-GC had even significantly elevated mean systolic (125.0 mmHg, IQR 117.5-130.0 vs 116.5 mmHg IQR 111.8-124.8; p = 0.036) and diastolic (78.0 mmHg, IQR 74.3-83.8 vs 74.5mmHG, IQR 69.3-76.0; p = 0.044) during the day. Systolic dipping was however more pronounced in those on GC in comparison to those taking HC (11.3%; IQR 8.7-14.6 vs. 6.4 IQR 3.4-12.7; p = 0.031). In conclusion, we could show in this small, albeit well-balanced cohort that mineralocorticoid dosage does not significantly differ between patients receiving synthetic glucocorticoids or conventional hydrocortisone. Higher blood pressure values despite the tendency for higher renin levels in those on S-GC support the notion that the assessment of MR adequacy should be guided by the clinical picture and blood pressure on a regular basis.