In a 13‑year‑old with absent pubertal signs, which finding would most reassure you that this represents a constitutional delay of growth and puberty?

Delayed Bone Age Most Reassures Constitutional Delay

A delayed bone age compared to chronological age is the single most reassuring finding that distinguishes constitutional delay of growth and puberty (CDGP) from other causes of absent pubertal development in a 13-year-old. 1, 2

Why Delayed Bone Age is Diagnostic

• Delayed bone age is the hallmark feature of CDGP, indicating increased remaining growth potential that allows for catch-up growth during an extended growth period 1, 2

• This finding specifically differentiates CDGP from familial short stature, where bone age matches chronological age 1, 3

• The delayed bone age reflects the underlying maturational delay affecting both skeletal development and the hypothalamic-pituitary-gonadal axis 1

Why the Other Options Are Not Reassuring

Abnormal Gonadotropins

• Abnormal (persistently low) gonadotropins with low sex steroids are diagnostic of hypogonadotropic hypogonadism, not constitutional delay 2

• This finding would raise concern for permanent pathology requiring further investigation including MRI to exclude hypothalamic-pituitary lesions 4

Short Stature

• Short stature is present in approximately 91% of CDGP cases, making it a common but non-specific finding 1

• Short stature alone cannot distinguish between CDGP, familial short stature, growth hormone deficiency, chronic disease, or other pathologic causes 5, 3

• The key is not the presence of short stature but rather the growth velocity pattern: normal velocity after initial deceleration in the first 3 years of life is characteristic of CDGP 1, 2

Normal Bone Age

• A normal bone age matching chronological age would argue against CDGP and instead suggest familial short stature or other causes 1, 2, 3

• In familial short stature, bone age is normal, growth velocity is normal (4-7 cm/year), and predicted adult height falls within mid-parental target range 3

Additional Supportive Features of CDGP

• Family history of delayed puberty in one or both parents is present in approximately 75% of cases 4, 6

• Male predominance with boys affected 4-5 times more frequently than girls 1

• Normal growth velocity during childhood (after initial deceleration) distinguishes CDGP from growth hormone deficiency 1, 2

• Eventual spontaneous pubertal progression before age 18 years differentiates CDGP from permanent hypogonadotropic hypogonadism 1, 2

Clinical Pitfall to Avoid

Do not confuse "delayed bone age" with "normal bone age"—these have opposite diagnostic implications. Delayed bone age (younger than chronological age) supports CDGP, while normal bone age (matching chronological age) suggests familial short stature and excludes CDGP 1, 2, 3