Objective: Low dose cranial irradiation in children with acute lymphoblastic leukaemia (ALL) has been reported to reduce GH secretion in puberty. A recent study also reported a disturbed periodicity of GH secretion during puberty. We have focused on the different stages of puberty in studying these two parameters of GH secretion and have also compared the effects of 18 vs 24 Gy radiation dose.
Patients and measurements: Thirty-four children previously treated for ALL were compared with a control group of 208 healthy normally growing children. GH secretion was measured as 24-hour profiles.
Results: In children treated for ALL, GH secretion rate and GH peak amplitude were below the median values for controls, both before puberty and during all stages of puberty. The difference between patients and controls was most pronounced in late puberty. Radiation with 18 or 24 Gy gave similar results. However, time sequence analysis showed a similar periodicity of GH secretion in both patient and control groups before, as well as during, puberty. Thus, before puberty a broad range of cycles per 24 hours was seen. These synchronized during puberty to a predominant GH peak frequency of one every 3-4 hours.
Conclusions: After low dose cranial irradiation with 18 or 24 Gy, the total amount of GH secreted is reduced both before and during puberty. We could not confirm previous findings of impaired periodicity of GH secretion in these children.