Epidemiology and Causes of Primary Adrenal Insufficiency in Children: A Population-Based Study

CONTEXT: Incidence and causes of primary adrenal insufficiency (PAI) have not been comprehensively studied in children. OBJECTIVE: Our objective was to describe the epidemiology and to assess causes of PAI in Finnish children. METHODS: A population-based descriptive study of PAI in Finnish patients aged 0-20 years.Diagnoses referring to adrenal insufficiency in children born in 1996-2016 were collected from the Finnish National Care Register for Health Care. Patients with PAI were identified by studying patient records. Incidence rates were calculated in relation to person-years in the Finnish population of same age. RESULTS: Of the 97 patients with PAI, 36% were female. The incidence of PAI was highest during the first year of life (in females 2.7 and in males 4.0/100 000 person-years). At 1-15 years of age, the incidence of PAI in females was 0.3/100 000 and in males 0.6/100 000 person-years. Cumulative incidence was 10/100 000 persons at age of 15 years and 13/100 000 at 20 years. Congenital adrenal hyperplasia was the cause in 57% of all patients and in 88% of patients diagnosed before age of 1 year. Other causes among the 97 patients included autoimmune disease (29%), adrenoleukodystrophy (6%), and other genetic causes (6%). From the age of 5 years, most of the new cases of PAI were due to autoimmune disease. CONCLUSION: After the first-year peak, the incidence of PAI is relatively constant through ages 1-15 years, and 1 out of 10 000 children are diagnosed with PAI before the age of 15 years.