What screening is indicated for a 14-year-old male with coarse, broad facial features and a prominent forehead?

Screen for Growth Hormone Excess and Genetic Syndromes

A 14-year-old male with coarse/broad facial features and prominent forehead should be screened for growth hormone (GH) excess with serum IGF-1 measurement, height velocity assessment, and pituitary MRI if biochemically positive. 1

Primary Screening Approach

Immediate Clinical Assessment

Measure and plot the following parameters:

• Height: Compare to age-adjusted, sex-adjusted, and ethnicity-adjusted norms (>2 SDS above mean is significant)
• Height velocity: Persistently elevated (>2 SDS) suggests GH excess
• Mid-parental height: Height >2 SDS above mid-parental target height is concerning
• Serial photographs: Review to time onset of facial changes 1

Key Physical Examination Findings to Document

Beyond the coarse facial features and frontal bossing already noted, specifically assess for:

• Acral enlargement: Hands, feet disproportionately large
• Dental changes: Teeth separation, malocclusion, prognathism
• Pubertal status: Delayed or arrested puberty (suggests gonadotrophin deficiency from mass effect)
• Visual fields: Formal testing if available
• Joint examination: Pain, hypermobility
• Skin: Acanthosis nigricans, café-au-lait spots, skin tags 1

Biochemical Screening

First-Line Testing

Order serum IGF-1 (age-adjusted, sex-adjusted, AND Tanner stage-matched reference ranges are critical). This is the most reliable marker for GH excess in adolescents. 1

Important caveats for IGF-1 interpretation:

• Marginal elevation during peak adolescent growth spurt requires cautious interpretation
• Falsely normal/low with: severe hypothyroidism, malnutrition, severe infection
• Falsely elevated with: poorly controlled diabetes, hepatic/renal failure, oral estrogens 1

Confirmatory Testing if IGF-1 Elevated

Oral glucose tolerance test (OGTT): Failure to suppress GH below 1 μg/L after oral glucose load supports GH excess diagnosis, though complete suppression can be difficult in normal adolescence. 1

Imaging

Contrast-enhanced pituitary MRI if biochemical testing suggests GH excess. This identifies somatotrophinomas in most cases. 1

Genetic Considerations

Nearly 50% of pediatric gigantism cases have an identifiable genetic basis, making genetic assessment particularly important. 1

When to Pursue Genetic Testing

Consider genetic evaluation if:

• Confirmed GH excess at age 14
• Early-onset features (before age 5 suggests X-linked acrogigantism)
• Associated findings suggesting specific syndromes:
  • McCune-Albright: Café-au-lait spots, fibrous dysplasia, precocious puberty
  • Carney complex: Skin pigmentation, myxomas, testicular/adrenal disease
  • MEN1: Consider if pituitary adenoma confirmed (genetic testing recommended for pituitary adenomas <30 years) 2, 3, 2

Specific Genetic Testing Pathway

If pituitary adenoma confirmed:

• MEN1 gene testing should be considered for any pituitary adenoma in a patient <30 years 3, 2
• If MEN1 positive, screen for primary hyperparathyroidism (serum calcium, PTH) and pancreatic neuroendocrine tumors 3, 2

Alternative Differential Diagnoses

While GH excess is the primary concern given the age and presentation, also consider:

RASopathies (Lower Priority but Worth Noting)

Cardio-facio-cutaneous syndrome (CFC): Coarse facial features, tall forehead, but typically presents with:

• Macrocephaly/relative macrocephaly
• Sparse, curly, friable hair with sparse eyebrows
• Cardiac abnormalities (75% have cardiovascular involvement, especially pulmonary valve stenosis)
• Developmental delay/intellectual disability
• Short stature (NOT tall stature) 4

Costello syndrome: Similar coarse features but distinguished by:

• Papillomata, loose skin
• Multifocal atrial tachycardia
• Short stature 4

These RASopathies are LESS likely in your patient because they typically present with short stature, not the tall stature/accelerated growth expected with GH excess at age 14. 4

Critical Pitfalls to Avoid

1. Do not dismiss mild IGF-1 elevation in adolescence without considering Tanner stage-matched norms and clinical context
2. Do not delay pituitary imaging if biochemical testing is positive—visual field defects can develop
3. Do not forget to assess for genetic syndromes even if isolated pituitary adenoma is found (50% have genetic basis in pediatrics)
4. Do not use adult reference ranges for IGF-1 or GH suppression testing in adolescents

Summary Algorithm

1. Measure height, calculate height velocity, compare to mid-parental height
2. Order serum IGF-1 (Tanner stage-matched)
3. If IGF-1 elevated: Perform OGTT for GH suppression testing
4. If biochemically positive: Obtain contrast-enhanced pituitary MRI
5. If pituitary adenoma confirmed: Refer to genetics for MEN1 and other genetic syndrome evaluation
6. Assess visual fields and endocrine function (prolactin, thyroid, cortisol, gonadotropins)