Evaluation of growth hormone provocative tests in Egyptian children with growth hormone-related short stature

Table 1 Demographic data of the studied cases

Variables	Total cases, n = 50	Patients’ subgroups		P value
		GHD group (n = 24)	ISS (n = 26)
Age/years				0.324
mean ± SD	10.3 ± 2.91	9.83 ± 3.37	10.73 ± 2.39
Sex, n (%)				0.616
Male	17 (34)	9 (37.5)	8 (30.8)
Females	33 (66)	15 (62.5)	18 (69.2)
Weight/kg				0.099
mean ± SD	26.67 ± 9.72	25.08 ± 9.8	28.13 ± 9.6
Weight Z score				0.207
Median (IQR)	-1.7 (-2.8 to -1.29)	-1.835 (-3.2 to -1.35)	-1.55 (-2.02 to -1.26)
Height/cm				0.180
mean ± SD	121.86 ± 14.79	118.46 ± 16.94	125 ± 11.98
Height Z score				0.129
mean ± SD	-2.77 ± 0.61	-2.88 ± 0.59	-2.68 ± 0.63
BMI				0.831
mean ± SD	17.37 ± 3.73	17.49 ± 3.86	17.26 ± 3.68
BMI Z score				0.977
Median (IQR)	-0.16 (-1.12 to 0.29)	-0.12 (-1.4 to 0.25)	-0.235 (-0.8 to 0.39)
Mid parenteral height				0.846
mean ± SD	165.93 ± 7.51	165.77 ± 7.31	166.08 ± 7.83
IGF (ng/mL)				0.662
mean ± SD	169.77 ± 38.39	165.73 ± 39.71	173.49 ± 37.52
IGF Z score				0.727
Median (IQR)	-0.87 (-1.4 to 0.53)	0.53 (-0.39 to 1.44)	0.9 (0.46 to 1.54)
Chronological age - bone age/years				0.537
mean ± SD	2.49 ± 0.88	2.54 ± 0.59	2.44 ± 1.1

IQR: Interquartile range; BMI: Body mass index; IGF: Insulin-like growth factor; GHD: Growth hormone deficiency; ISS: Idiopathic short stature.

Table 2 Comparing the percentage of cases with optimal growth hormone response (≥ 10 ng/mL) in different provocative tests in each test sample, n (%)

Sampling time	Insulin tolerance test (n = 50)	Clonidine test (n = 50)	L-DOPA test (n = 50)	P value
Basal sample	2 (4)	1 (2)	1 (2)	0.773
Sample 2 (30 minutes)	5 (10)	3 (6)	5 (10)	0.714
Sample 3 (45 minutes)	6 (12)	6 (12)	1 (2)	0.121
Sample 4 (60 minutes)	3 (6)	4 (8)	7 (14)	0.359
Sample 5 (90 minutes)	1 (2)	11 (22)	3 (6)	0.001a
Sample 6 (120 minutes)	3 (6)	7 (14)	3 (6)	0.259

^aP value < 0.05 is considered significant. Cases may have more than one sample with growth hormone ≥ 10 ng/mL.

GH: Growth hormone; L-DOPA: Levodopa.

Table 3 Optimal cut-off points of peak growth hormone responses to provocative tests, %

Variables	AUC	Cut-off, ng/mL	Sensitivity	Specificity	PPV	NPV	Accuracy
GH provocation test by insulin	0.764	7.54	59.3	91.3	65.6	88.9	74
GH provocation test by clonidine	0.844	8.48	77.8	82.6	76	84	80
GH provocation test by L-DOPA	0.755	4.63	80	70	84.6	66.7	76

AUC: Area under curve; PPV: Positive predictive value; NPV: Negative predictive value; GH: Growth hormone; L-DOPA: Levodopa.