Growth hormone provocation tests and their prediction in the growth of children treated for acute lymphoblastic leukemia.

AIM: The aim of this study was to evaluate the positive predictive value of two growth hormone stimulation tests (insulin-induced hypoglycemia and clonidine) for stature below percentile 10 in patients treated for acute lymphoblastic leukemia in childhood. METHODS: The study population was a cohort of 30 patients (aged 14.1+/-2.9 years; 20 male) treated for acute lymphoblastic leukemia during childhood and then examined after insulin-induced hypoglycemia (30 patients) and clonidine (16 patients) tests. The follow-up time was 7.7+/-2.8 years since treatment and 2.3+/-1.3 years after administration of the tests. RESULTS: In the last evaluation, 12 patients (40%) were below and 18 (60%) were above percentile 10. The insulin-induced hypoglycemia test response was: 9 patients (30%) had growth hormone peak <5 ng/mL and 19 (63.3%) <7 ng/mL. The clonidine test response was: 7 patients had growth hormone peak <5 ng/mL and 8 (50%) <7 ng/mL. For stature below of the percentile 10, the positive predictive values of insulin-induced hypoglycemia test (33%) and clonidine (28%) were low when growth hormone peak <5 ng/mL was considered; however, when growth hormone peak <7 ng/mL was considered, the positive predictive values were 83% and 50% for the insulin-induced hypoglycemia and clonidine tests, respectively. CONCLUSIONS: In patients treated for acute lymphoblastic leukemia in childhood, the positive predictive values for statural deficit of both tests were low, except for the insulin-induced hypoglycemia test when a growth hormone peak <7 ng/mL was considered.