Growth hormone response to oral clonidine test in normal and short children

Abstract

We evaluated the growth hormone (GH) response to an acute clonidine test (0.15 mg/m2 po) in 30 normal prepubertal children (stature between the 3rd and 97th centile), in 29 short children (stature < 3rd centile for age) with height velocity (HV) > 10th centile and in 20 short children with HV < 10th centile. The three groups had comparable chronological ages. After clonidine administration mean peak GH levels were similar in the three groups (19.4 +/- 9.8, 17.7 +/- 8.8 and 14.6 +/- 8.9 micrograms/l, mean +/- SD, respectively). By choosing 10 micrograms/l as the limit for a normal response we found that stimulated GH levels had a sensitivity of 50% and a specificity of 83% in identifying children with suspected GHD (short children with subnormal HV). The diagnostic accuracy was almost superimposable, for cut-off values of 10 and 12 micrograms/l. Eight of the 10 children with subnormal HV and a GH peak < 10 micrograms/l had a GH peak < 10 micrograms/l also after a second stimulation test. Six of the 29 short children with normal HV had a GH peak < 10 micrograms/l. Only one of them had a GH peak < 10 micrograms/l after a second stimulation test. Five of the normal children had peak GH levels < 10 micrograms/l. These results indicate that HV is a useful variable to predict the GH response to an acute GH stimulus, since the great majority of children with a normal growth rate had a normal GH response to at least one stimulation test.

Retesting the childhood-onset GH-deficient patient

“…These studies have generally been performed in different cohorts of GHD patients with classical provocative tests that are known for their poor reproducibility (30)(31)(32)(38)(39)(40). This evidence clearly led to the statement that there is no justification for the view that patients diagnosed in childhood to be GHD should continue on therapy into adult life without their GH status being reinvestigated and shown to be persistently abnormal.…”

“…The inability to confirm GHD in adulthood could reflect transient GHD in childhood (34) or, alternatively, could merely reflect the lack of reproducibility of classical provocative tests (30)(31)(32)(38)(39)(40). It also has to be considered that even patients with normal GH response to provocative tests but showing impairment of spontaneous GH secretion are presently considered as GH insufficient (the so-called GH neurosecretory dysfunction) and treated with rhGH for replacement (41).…”

Intoxication pédiatrique sévère avec une faible dose de clonidine : à propos d’un cas

“…La dose de béta-xolol à administrer pour ce test est la même pour la plupart des auteurs soit 0,25 mg/kg [9,10]. En revanche, on retrouve différentes recommandations en ce qui concerne la clonidine : 0,15 mg/m 2 [10][11][12][13] ou 0,025 mg/m 2 [9]. C'est cette dernière qui avait été prescrite dans notre observation.…”

Somatostatin Infusion Withdrawal: Studies in Normal Children and in Children with Growth Hormone Deficiency

“…One of the major problems of the provocative tests lies in their poor reproducibility (14,15) and in the great number of false negative responses frequently observed also in normal children (24,25). The reason for this variability has been attributed to the periodic secretion of SS, which may influence the somatotrope response to the stimulus (26).…”