Assessment of adrenal function in pediatric cancer survivors

Introduction
Oncological therapy can temporarily or permanently disrupt adrenal gland function. The aim of our study was to assess the function of adrenal glands in cancer survivors and to find the best diagnostic tools for it.

Material and methods
Sixty patients aged 1.2–14.9 years (mean 8.3 ±3.5) with diagnosed malignancies and 45 healthy children as controls were recruited to the study. Patients were assessed 0–8 years (mean 2.4 ±2.0 years) after the oncological therapy. In all patients fasting blood samples were collected to measure: glucose, sodium, potassium, cortisol, aldosterone, plasma renin activity (PRA), dehydroepiandrostenedione-sulphate (DHEA-S), adrenocorticotropic hormone (ACTH) and antibodies against the adrenal cortex (AAA). Moreover, 24-hour urinary free cortisol (UFC) was assessed. Test with synthetic ACTH was carried out with 250 µg in neuroblastoma and nephroblastoma patients and with 1 µg in other oncological patients.

Results
The levels of morning cortisol and sodium were significantly lower and blood glucose were higher in cancer survivors than in controls (p = 0.006, p = 0.043, p = 0.008). Basal laboratory tests confirmed adrenal insufficiency (AI) in 1 patient with neuroblastoma. Low-dose ACTH revealed AI in 3 patients with acute lymphoblastic leukemia. In the study group, UFC correlated with evening and midnight cortisol (p = 0.001, p = 0.006). In the control group UFC correlated with DHEA-S (r = 0.623, p = 0.0001). None of assessed parameters correlated with the time since the completion of oncological therapy.

Conclusions
The study confirmed possibility of developing asymptomatic AI in cancer survivors even several years after therapy. Instead of morning cortisol, classical diagnostic low-dose ACTH test seems to be an optimal tool for adrenal function’s assessment.