Background Congenital adrenal hyperplasia (CAH) is an autosomal recessive condition with significant consequences if not correctly diagnosed and treated. We have reviewed the patients with CAH presenting in Northern Ireland between 1976 and 2010.

Aims To determine the age, sex and clinical features at presentation; treatment modalities including perineal surgery in childhood; and long-term outcomes including final height and surgery in adulthood.

Methods The medical notes of patients diagnosed with CAH in this time period were reviewed. A literature review was performed and our data compared with that previously published.

Results 37 patients (22 female, 15 male) from 30 families presented with CAH over this time period giving an incidence of 1:23,092 live births. 18 (49%) were diagnosed shortly after birth (83% virilised females); 13 (35%) presented in the first few weeks of life with adrenal crises (85% male); and 6 (16%) presented with virilisation in later childhood. 6 (16%) children had diagnosis confirmed on genetic testing. All children required glucocorticoid replacement. 35 (95%) required mineralocorticoid replacement; 3 children were treated with growth hormone and 2 children required suppression of early puberty. Mean final height was −1.5 SD below mean adult height in boys and girls. In the first 16 years reviewed, 8 (80%) girls had perineal surgery in childhood, compared with 2 (16%) in the second 18 years. 2 (9%) women had adrenalectomy. 11 (58%) of those transferred to adult services have been lost to follow-up.

Conclusions The incidence of CAH is less here than in the rest of the United Kingdom with more females affected than males. The majority present in the first few weeks of life. Mean final height is often impaired. There is a trend towards later surgery in these patients. A large number of adult patients have been lost to follow-up suggesting a need for improved transitional services.