Table 3.

Biomarkers in 21OHD: significance, uses, and limitations

Steroid	Significance	Uses	Limitations
17OHP	Immediately above block	Titrate GC	Varies widely from dose
21dF	Purely adrenal steroid	Diagnosis	Mass spectrometry
A4	Proximate 19-carbon steroid	Titrate GC	Also derives from gonads
Testosterone	Active androgen	Titrate GC	Also derives from gonads
11OHA4	Major adrenal product	Titrate GC	Limited data in management
11KT	Purely adrenal androgen	Titrate GC	Limited data in management
Progesterone	Affects endometrium	Female fertility	Must be follicular phase
PRA/renin mass	Volume status	Titrate mineralocorticoid	Renal insufficiency

Abbreviations: 11KT, 11-ketotestosterone; 11OHA4, 11β-hydroxyandrostenedione; 17OHP, 17-hydroxyprogesterone; 21dF, 21-deoxycortisol; 21OHD, 21-hydroxylase deficiency; A4, androstenedione; GC, glucocorticoid; PRA, plasma renin activity.