Congenital adrenal hyperplasia (CAH)

What changes during this transition

Congenital adrenal hyperplasia is a group of autosomal recessive disorders of adrenal steroidogenesis. ~95% of cases are 21-hydroxylase deficiency (21-OHD, CYP21A2). The biology is shared: an enzyme block in cortisol synthesis causes loss of negative feedback, ACTH rises, the adrenal gland hyperplases trying to make cortisol, and steroid precursors get shunted into androgen pathways. The clinical picture is dictated by which enzyme is missing and how completely. 21-OHD itself runs a severity spectrum. Classic salt-wasting (~75% of classic cases) is the neonatal emergency presentation: severe cortisol AND aldosterone deficiency plus androgen excess. Untreated, infants present in the first weeks of life with vomiting, dehydration, hyperkalemia, hyponatremia, and shock — a salt-wasting crisis. 46,XX infants typically have ambiguous genitalia from in-utero androgen exposure; 46,XY infants look phenotypically male and historically were diagnosed only after crisis (the case for universal newborn screening). Classic simple virilizing (~25% of classic) preserves enough aldosterone to avoid salt-wasting crisis but has cortisol deficiency and androgen excess. Non-classic CAH is the late-onset phenotype — partial enzyme activity, no neonatal crisis, presents in adolescence or adulthood as hyperandrogenism that often gets initially diagnosed as PCOS until a 17-OHP draw clarifies things. The US has screened all newborns for 17-hydroxyprogesterone since the 1990s — a public-health win that converted what used to be a catastrophic-presentation disease into one usually caught in the first week of life. Diagnostic workup confirms with ACTH stimulation testing, CYP21A2 genotyping, baseline cortisol/aldosterone/plasma renin activity, and karyotyping when genitalia are ambiguous. Standard of care is glucocorticoid replacement — hydrocortisone preferred in children because it has the shortest half-life and the least growth suppression, with prednisone or dexamethasone used more commonly in adults. The therapeutic goal is doubled: replace deficient cortisol AND suppress the excess ACTH that's driving androgen overproduction. That dual goal is also the disease's central trade-off: you need enough glucocorticoid to suppress ACTH, but every milligram past physiologic replacement carries glucocorticoid side effects compounded over a lifetime. Salt-wasters add fludrocortisone for mineralocorticoid replacement and salt supplementation in infancy. Like primary adrenal insufficiency, CAH patients carry stress-dosing protocols and emergency injectable hydrocortisone for acute illness, surgery, or trauma — adrenal crisis is the lifelong baseline risk. December 2021 brought the first novel CAH therapy in decades: Chronocort/Efmody, a modified-release hydrocortisone that better mimics circadian cortisol rhythms, FDA-approved for adults. Then December 2024 brought the paradigm shift: crinecerfont (Crenessity), a CRF1 receptor antagonist that blocks the upstream signal driving ACTH overproduction. By reducing the ACTH drive, crinecerfont allows hydrocortisone doses to drop ~30% while maintaining androgen control — the first non-steroid mechanism approved for classic CAH, and the first drug that addresses the over-treatment trade-off head-on instead of just optimizing within it. Tildacerfont, another CRF1 antagonist in the SPARK-T and SPARK-A Phase 3 programs, is following the same playbook. Surgical considerations are some of the most editorially loaded ground in pediatric endocrinology. Feminizing genitoplasty for 46,XX virilized infants — once routinely performed in the first year of life — is now widely understood as ethically fraught. Current consensus from many specialty societies, intersex advocacy organizations, and a growing number of CAH-care centers favors delaying non-emergent genital surgery until the child can participate in the decision, with the recognition that gender identity in 46,XX CAH does not always align with the female sex of rearing. CARES Foundation (Congenital Adrenal Hyperplasia Research, Education, and Support) and the CAH Quality Care Initiative track outcomes and advocate for patient-centered care models. Long-term, the burden of CAH is mostly the burden of glucocorticoid exposure. Over-treatment causes short stature (the historical scourge in children — glucocorticoids suppress growth), reduced bone mineral density, metabolic syndrome, hypertension, mood effects, and the compounding side-effect signature of any chronic steroid exposure. Under-treatment lets androgens stay elevated, driving virilization, accelerated bone age in children, infertility, and in males the development of testicular adrenal rest tumors (TARTs) — adrenal tissue lodged in the testes that becomes hyperactive under high ACTH drive. Threading the needle between under- and over-treatment across a lifetime is the actual clinical work. Crinecerfont's promise is that the needle gets a wider eye. Transition to adult care is its own load-bearing problem. The handoff from pediatric endocrinology to adult endocrinology is where many CAH patients fall through the cracks. CARES and adult CAH-care centers have built structured transition protocols. Fertility planning is similarly load-bearing: women with classic CAH have reduced fertility, men face TART-related infertility, both face pregnancy management questions. Mental health support — for body image, gender identity exploration, the burden of lifelong daily medication, and the specific traumas some patients carry from non-consensual childhood surgery — belongs in the standard care package. Peptides have no established role in CAH management. The disease is not adrenal damage or autoimmune destruction — it's a genetic enzyme deficiency. The adrenal gland is intact (hyperplasic, in fact); the problem is one specific catalytic step is broken or missing. No peptide restores CYP21A2 function, replaces cortisol, or substitutes for fludrocortisone in salt-wasters. The legitimate therapeutic story here is endocrinology, and that story changed materially in December 2024.