ESPE Abstracts

Objective: Incidence and causes of primary adrenal insufficiency (PAI) have not been comprehensively studied in children. Our objective was to describe the epidemiology and to assess national causes of PAI in children.

Design: A national population-based descriptive study of PAI in patients aged 0-20 years.

Methods: Diagnoses referring to adrenal insufficiency in children born in 1996-2016 were collected from the national health care register. Patients with PAI and the causes of the disease were identified by studying patient records. Incidence rates were calculated in relation to the person-years in the national 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: 3.4/100,000 person-years (in females 2.7/100,000 and in males 4.0/100,000). At 1-15 years of age, the total incidence of PAI was 0.4/100,000, in females 0.3/100,000, and in males 0.6/100,000 person-years. Cumulative incidence was 10/100,000 persons at the age of 15 years and 13/100,000 persons at 20 years of age. Congenital adrenal hyperplasia was the cause in 57% of all patients and in 88% of patients diagnosed before age of one year. Other causes among the 97 patients included autoimmune disease (29%), adrenoleukodystrophy (6%), and other genetic causes (6%). From the age of five years, most of the new cases of PAI, and after the age of eight years 95% of new cases of PAI were due to autoimmune disease.

Conclusion: After the first-year peak, the incidence of PAI is relatively constant through ages of 1-15 years. One out of 10,000 children are diagnosed with PAI before the age of 15 years. PAI during the first four years of life is most likely due to CAH but autoimmune disease is the most prevalent cause later in childhood.