Blum et al developed new biochemical criteria for the diagnosis of growth hormone receptor deficiency (GHRD), with the addition of 2 criteria to those of Savage et al (previous section). The authors are from Tubingen University Children's Hospital (Germany), St. Bartholomew's Hospital (London) and the Karolinska Institute (Stockholm).
Parameters:
(1) basal serum growth hormone in µg/L
(2) serum IGF-I in µg/L
(3) IGF-I generation test (after administration of exogenous growth hormone)
(4) height expressed in standard deviation (Z) score
(5) percent growth hormone binding protein (based on binding uptake of I125-GH)
(plus new criteria)
(6) basal IGFBP-3 (IGF binding protein)
(7) IGFBP-3 generation (after administration of exogenous growth hormone)
Parameter |
Finding |
Points |
---|---|---|
basal serum growth hormone |
< 2.5 µg/L |
0 |
|
>= 2.5 µg/L |
1 |
basal serum IGF-I |
> 50 µg/L |
0 |
|
<= 50 µg/L |
1 |
IGF-I generation |
>= 15 µg/L |
0 |
|
< 15 µg/L |
1 |
height |
>= -3 standard deviations below mean |
0 |
|
< -3 standard deviations below mean |
1 |
percent GH binding protein |
>= 10% |
0 |
|
< 10% |
1 |
basal IGFBP-3 |
>= -2 SDS (2 standard deviations below mean) |
0 |
|
< -2 SDS |
1 |
IGFBP-3 generation |
>= 0.4 mg/L |
0 |
|
< 0.4 mg/L |
1 |
where:
• The basal serum growth hormone cutoff was changed from the Savage score. The initial value was 4 mU/L which apparently is about 2.5 µg/L.
• IGF-1 increase is now expressed in µg/L rather than as percent of intra-assay variability.
• IGF-I and IGFBP-3 generation appears to be the difference between basal level and level after administration of exogenous growth hormone).
total score =
= SUM(points for all 7 parameters)
Interpretation:
• minimum score: 0
• maximum score: 7
• A score >= 5 indicates growth hormone receptor deficiency (GHRD).
Limitations:
• The assays would need to be standardized to give comparable results.
Purpose: To evaluate a patient for growth hormone receptor deficiency (GHRD) using the criteria of Blum et al.
Specialty: Endocrinology, Clinical Laboratory
Objective: risk factors, laboratory tests
ICD-10: E23,