Endocrine Abstracts (2002) 3 P25

Congenital adrenal hyperplasia: A tale of two enzymes

O Chaudhri, C Goodlad, A Hameed, M Barakat & K Meeran

Imperial College School of Medicine Endocrine Unit, Hammersmith Hospital, London, UK;

A 24-year old male who, was normal at birth, became listless and volume depleted at 3 weeks of age. Investigations yielded an Addisonian picture (serum Na+ 115 mmol/l; K+ 8.2 mmol/l; urea 15.8 mmol/l). Serum 17-hydroxyprogesterone (17-OHP) levels were measured and found to be high (2,564 nmol/l). Urinary 17-oxosteroids and 17-OHP were also elevated. The neonate was thought to have 21-hydroxylase-deficient congenital adrenal hyperplasia (CAH) and therapy with fludrocortisone and dexamethasone commenced. Levels of 17-OHP suppressed well. At age 13 months, the subject was referred to paediatric endocrinologists for titration of the dose of hydrocortisone to allow for adequate growth. He settled on 20mg a.m. and 10mg p.m. of hydrocortisone, and 100mcg of fludrocortisone daily, and remained well for the next 22 years, with normal range serum 17-OHP levels and normal blood pressure.

However, he was then noted to be hypertensive (150/106 mmHg). Repeat serum 17-OHP levels were elevated (82.9 nmol/l), consistent with less than full compliance with therapy. Serum 11-deoxycortisol levels were also elevated, however (33.9 nmol/l), and the diagnosis revised to 11-hydroxylase-deficient CAH. Fludrocortisone therapy was stopped and serum electrolytes and blood pressure have thus far remained normal.

While 21-hydroxylase deficiency remains the commonest form of CAH, it is important to distinguish this form from 11-hydroxylase deficiency, as the latter is associated with hypertension due to high deoxycorticosterone levels, and the use of fludrocortisone may compound this. Clinical features and serum electrolyte measurements cannot be relied upon; both conditions comprise a spectrum of disease and the literature describes cases of 11-hydroxylase-deficient patients who have demonstrated urinary salt loss, both on presentation, and also after commencement of steroid therapy.

We advocate the measurement of 11-deoxycortisol levels in addition to levels of 17-OHP in all patients in whom CAH is suspected.

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