Guidelines for Evaluation and Management of Delayed Bone Age and Suspected Growth‑Hormone Deficiency in Children

Auxologic Assessment

Plot height and weight on standardized growth charts; a decline across percentiles or height below the 3rd percentile indicates pathologic growth failure rather than a normal variant. 1
Calculate mid‑parental height to compare the child’s growth trajectory with expected genetic potential. 1
Measure height velocity over a 6‑ to 12‑month interval; a reduced velocity that is not explained by familial patterns is a key trigger for further endocrine work‑up. 2
Document bone‑age delay; a delay of ≥ 2.2 SDs (≈ 1.2–1.7 years at 6 y 9 m) suggests significant pathology. 1

Feeding difficulties or failure to thrive are frequently associated with growth‑hormone deficiency. 1
Episodes of hypoglycaemia in infancy may point to congenital growth‑hormone deficiency. 1
Midline facial anomalies or visual‑field defects raise suspicion for structural pituitary abnormalities. 1
Co‑existing deficiencies of other pituitary hormones (e.g., hypothyroidism, adrenal insufficiency) increase the likelihood of growth‑hormone deficiency. 2

Measure serum IGF‑I and IGFBP‑3; in children > 3 years, IGFBP‑3 often provides superior screening sensitivity. 1
Low IGF‑I and IGFBP‑3 (< ‑2 SD) together with severe growth failure and delayed bone age strongly suggest growth‑hormone deficiency. 2
Perform thyroid‑function tests (TSH, free T4) because hypothyroidism can impair both linear growth and bone maturation. 1

Indications: (1) auxologic criteria met (declining height SD or reduced velocity), (2) IGF‑I/IGFBP‑3 low, (3) markedly delayed bone age, and (4) no alternative cause identified. 2
Testing can be omitted when any of the following are present: pituitary lesion on imaging plus auxologic criteria; documented deficiency of another pituitary hormone; extreme short stature (height < ‑3 SD) with low IGF‑I/IGFBP‑3 and delayed bone age; or normal bone age with normal height velocity. 2
Diagnostic GH peak cutoff in the United States is < 10 ng/mL; some experts advocate a stricter < 7 ng/mL when using harmonized assays. 2
Preferred stimulation agents: arginine, glucagon, clonidine (insulin‑tolerance test is no longer recommended due to hypoglycaemia risk). 1
Recognised limitations: results are affected by BMI, lack of sex‑steroid priming in pre‑pubertal children, and the arbitrary nature of cut‑off values. 2

Obtain MRI of the hypothalamic‑pituitary region once biochemical evidence of growth‑hormone deficiency is established. 2
Look for ectopic posterior pituitary, a thin or interrupted pituitary stalk, or pituitary stalk interruption syndrome; such findings predict future pituitary hormone deficits and help assess the permanence of deficiency. 1 2
Identify possible structural lesions such as Rathke’s cleft cysts, craniopharyngiomas, or other masses. 2

Start daily subcutaneous recombinant human growth hormone (somatropin) at a dose of approximately 0.22–0.30 mg/kg/week. 1

Check thyroid function intermittently during the first year of GH therapy, as thyroxine levels may fall and require replacement. 1
Re‑measure IGF‑I periodically to verify adequate dosing and treatment response. 1

Severe growth failure (height < ‑3 SD) + low IGF‑I/IGFBP‑3 + delayed bone age → proceed directly to MRI and consider GH therapy without provocation testing. 2
Moderate growth concerns with declining height velocity and low biochemical markers → perform provocation testing; if positive, obtain MRI and initiate therapy. 2
Normal height velocity and normal IGF‑I/IGFBP‑3 → likely constitutional delay or familial short stature; provide reassurance and routine monitoring. 2
Any additional pituitary hormone deficiency together with auxologic criteria → diagnose growth‑hormone deficiency without provocation testing, then image and treat. 2

Do not rely on bone‑age delay alone; it is a common finding in constitutional growth delay and familial short stature.
Avoid provocation testing unless auxologic criteria are satisfied, to prevent over‑diagnosis and unnecessary treatment. 2
Consider nutritional status, as IGF‑I levels are influenced by weight gain, adiposity, and feeding patterns. 1

Testing should be performed only when auxologic criteria are met – a decline in height standard‑deviation score or reduced height velocity that cannot be explained by familial pattern, together with low IGF‑I and/or IGFBP‑3 and a bone age delayed by ≥2 SD; the diagnostic GH‑peak cutoff used in the United States is <10 ng/mL. 3, 4, 5
Testing should be omitted in children who have a documented pituitary abnormality on imaging plus auxologic criteria, a deficiency of another pituitary hormone, extreme short stature (height < ‑3 SD) with low IGF‑I/IGFBP‑3 and delayed bone age, or normal bone age with normal height velocity. 4, 5
Provocation testing must never be the sole diagnostic criterion; results must be interpreted in conjunction with auxologic findings, IGF‑I, IGFBP‑3, and bone‑age assessment. 3, 4

Standard U.S. diagnostic cutoff: a peak GH concentration < 10 ng/mL on clonidine or arginine stimulation indicates growth‑hormone deficiency. 3, 4, 5
Alternative, assay‑specific cutoff: when using harmonized immunoassays calibrated to the IS 98/574 standard, a more stringent cutoff of < 7 ng/mL is advocated by some experts. 3, 5

Pubertal status: lack of sex‑steroid priming in prepubertal children can affect GH‑stimulus results, but clonidine testing shows consistent performance across both prepubertal and pubertal children. 3

Assay standardization: laboratories should employ harmonized GH assays calibrated to the IS 98/574 (22 kDa recombinant human GH isoform) standard to ensure comparable results. 3, 5
Assay variability: different immunoassays may produce discrepant GH values because of varying antibody specificity for GH isoforms; clinicians must be aware of this variability when interpreting results. 3, 5

Do not initiate testing without meeting auxologic criteria, as this can lead to overdiagnosis and unnecessary treatment. 4