Stature Abnormal: Tall Stature & Short Stature

Introduction to Growth Disorders for MCCQE1

Abnormal stature is a frequent presentation in Canadian pediatric and family medicine practice. For the MCCQE1, understanding the distinction between normal variants of growth and pathological conditions is crucial. This topic falls under the Endocrinology and Pediatrics objectives.

As a Medical Expert, you must be able to interpret growth charts (WHO Growth Charts for Canada), calculate growth velocity, and identify “red flags” requiring referral. As a Health Advocate, you must communicate effectively with parents concerned about their child’s height, avoiding unnecessary medicalization of normal variants.

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Canadian Context: The Canadian Paediatric Society (CPS) and the College of Family Physicians of Canada (CFPC) recommend the use of the WHO Growth Charts for Canada (2014). Monitoring growth is a standard part of well-child visits in Canada.

Defining Abnormal Stature

Short Stature

Defined as a height:

< 3rd percentile for age and sex.
> 2 Standard Deviations (SD) below the mean.

Tall Stature

Defined as a height:

> 97th percentile for age and sex.
> 2 Standard Deviations (SD) above the mean.

Growth Velocity

The most critical factor in evaluating growth is velocity (rate of growth over time).

Pathologic: A child crossing percentile lines downward (short stature) or upward (tall stature) after the age of 2-3 years suggests pathology.
Normal Deceleration: Infants often cross percentiles in the first 2 years to find their genetic potential (“catch-up” or “catch-down” growth).

Short Stature: Etiology and Classification

For MCCQE1 preparation, classify short stature into three main categories:

Normal Variants (Most common)
Primary Growth Abnormalities (Intrinsic bone/genetic issues)
Secondary Growth Disorders (Systemic environment affecting growth)

Normal Variants

1. Familial Short Stature (FSS):

Short parents, normal birth weight.
Normal growth velocity.
Bone age = Chronological age.
Final height: Short (consistent with mid-parental height).

2. Constitutional Delay of Growth and Puberty (CDGP):

“Late bloomers.”
Often a family history of delayed puberty (menarche or growth spurt).
Normal growth velocity (tracking along a lower percentile).
Bone age < Chronological age.
Final height: Normal.

High-Yield Comparison: FSS vs. CDGP

This is a classic MCCQE1 discrimination task.

Feature	Familial Short Stature (FSS)	Constitutional Delay (CDGP)
Family History	Parents are short	Parents normal height; “Late bloomers”
Growth Velocity	Normal	Normal (but slow in pre-puberty)
Puberty Onset	Normal timing	Delayed
Bone Age	Equal to Chronological Age	Delayed (< Chronological Age)
Final Height Prediction	Short	Normal

Tall Stature: Etiology

Tall stature is less common as a complaint but clinically significant.

Constitutional/Familial Tall Stature

Tall parents.
Normal physical exam.
Bone age normal or slightly advanced.

Pathological Tall Stature

Endocrine:
- Pituitary Gigantism: Excess GH before epiphyseal closure (Adenoma).
- Precocious Puberty: Tall as a child, but early epiphyseal closure leads to short adult height.
- Hyperthyroidism.
Genetic Syndromes:
- Marfan Syndrome: FBN1 mutation. Tall, thin, arachnodactyly, lens dislocation (upward), aortic root dilation.
- Homocystinuria: Marfanoid habitus, intellectual disability, lens dislocation (downward), thrombotic events.
- Klinefelter Syndrome (47,XXY): Tall, long limbs, hypogonadism, gynecomastia.
- Sotos Syndrome: Cerebral gigantism, macrocephaly, developmental delay.
- Fragile X Syndrome.

Evaluation of Stature Abnormalities

Follow this step-by-step approach for your MCCQE1 clinical reasoning scenarios.

Step 1: History and Calculation of Mid-Parental Height (MPH)

Obtain heights of biological parents. Calculate the genetic target range.


# Mid-Parental Height Formula (Tanner Method)
 
Boys: [Father's Height (cm) + (Mother's Height (cm) + 13)] / 2
Girls: [(Father's Height (cm) - 13) + Mother's Height (cm)] / 2
 
Target Range: MPH ± 8.5 cm

Ask about: Birth weight (SGA?), family history of puberty timing, nutrition, systemic symptoms (GI, renal, cardiac), medications (steroids).

Step 2: Physical Examination

Anthropometry: Height, weight, head circumference.
Proportions: Arm span vs. height (Marfan’s), Upper/Lower segment ratio (skeletal dysplasia).
Dysmorphism: Webbed neck (Turner), frontal bossing (Achondroplasia).
Pubertal Staging: Tanner staging (delayed in CDGP).
Systemic: Goiter, murmurs, abdominal distension.

Step 3: Analyze the Growth Chart

Plot current height and previous points.
Critical Action: Calculate growth velocity.
Is the child crossing percentiles?
Is weight affected before height? (Suggests nutritional/systemic cause like Celiac).
Is height affected before weight? (Suggests Endocrine cause like Hypothyroidism or GH deficiency).

Step 4: Determine Bone Age

Order an X-ray of the left hand and wrist.

Compare “Bone Age” to “Chronological Age”.
Essential for distinguishing FSS from CDGP.

Step 5: Laboratory Investigations (Screening)

Only indicated if pathologic cause suspected (poor velocity, dysmorphism, symptoms).

CBC, ESR/CRP: Chronic inflammation.
Tissue Transglutaminase (tTG-IgA): Celiac screen (High yield for Canada).
TSH, Free T4: Hypothyroidism.
Karyotype: Mandatory for all females with unexplained short stature (Turner syndrome).
IGF-1 & IGF-BP3: Screen for GH deficiency (GH is pulsatile, so random GH is useless).
Electrolytes, Creatinine: Renal tubular acidosis, renal failure.

Management and Canadian Guidelines

General Principles

Treat the underlying cause: E.g., Gluten-free diet for Celiac, Thyroxine for Hypothyroidism.
Reassurance: For Familial Short Stature and CDGP. Explain the natural history.

Growth Hormone (GH) Therapy in Canada

GH therapy is expensive and strictly regulated. In Canada, approved indications typically include:

Proven GH Deficiency.
Turner Syndrome.
Prader-Willi Syndrome.
Chronic Renal Failure.
Small for Gestational Age (SGA) children who fail to catch up by age 2-4.
Idiopathic Short Stature (ISS): Controversial, not universally covered by provincial plans.

Canadian Clinical Pearl 🇨🇦

Celiac Disease is significantly more common in Canada compared to global averages. It can present with isolated short stature without classic GI symptoms. Always include tTG-IgA in your workup for unexplained short stature in the MCCQE1.

Key Points to Remember for MCCQE1

Growth Velocity: The single most important parameter. <4-5 cm/year in a school-aged child is abnormal.
Hypothyroidism: Can present as growth arrest with weight gain (myxedema).
Cushing’s: Growth arrest with weight gain.
Weight vs. Height:
- Weight drops first = Nutrition/Systemic.
- Height drops first (or weight gain) = Endocrine.
Turner Syndrome: Consider in ANY girl with short stature, even without webbed neck. Look for coarctation of the aorta and bicuspid aortic valve.
Bone Age: Differentiates CDGP (delayed) from FSS (normal).

Sample Question

Clinical Scenario

A 14-year-old male presents to the family physician with concerns about his height. He is the shortest boy in his class and is often teased. He feels well otherwise. His past medical history is unremarkable.

Height: 142 cm (< 3rd percentile)
Weight: 36 kg (5th percentile)
Sexual Maturity Rating (Tanner): Genitals Stage 1, Pubic Hair Stage 1.

His mother is 165 cm tall (50th percentile) and had menarche at age 12. His father is 178 cm tall (75th percentile) but mentions he continued to grow in college after high school graduation.

A review of the patient’s growth chart shows he has consistently tracked just below the 3rd percentile for height since age 3, with a normal growth velocity. An X-ray of the left hand reveals a bone age of 11.5 years.

Which of the following is the most likely diagnosis?

Options

Show Explanation

Explanation

The correct answer is:

C. Constitutional Delay of Growth and Puberty

Explanation: This is a classic presentation of Constitutional Delay of Growth and Puberty (CDGP), often referred to as a “late bloomer.”

Clinical Clues: The patient is short (<3rd percentile) but has a normal growth velocity (tracking parallel to the curve).
Family History: The father’s history of growing after high school (“late bloomer”) is highly suggestive of a genetic predisposition to delayed puberty.
Bone Age: The bone age (11.5 years) is significantly delayed compared to chronological age (14 years). This indicates “potential” for further growth.
Management: Reassurance is the primary management. He will likely reach a normal adult height consistent with his mid-parental height.

Why other options are incorrect:

A. Familial Short Stature: Bone age would be consistent with chronological age (14 years), and parents would typically be short. Here, the bone age is delayed, and parents are average/tall.
B. Growth Hormone Deficiency: This would typically present with a deceleration in growth velocity (falling off the curve) and the child would be “chubby” (weight relatively preserved compared to height), unlike this thin/proportional teenager.
D. Klinefelter Syndrome: Typically presents with tall stature, not short stature.
E. Celiac Disease: While Celiac can cause short stature, the growth velocity would likely be impaired (crossing percentiles downward), and weight would likely be more affected than height initially (wasting). The consistent tracking along the curve points away from pathology.

References

Canadian Paediatric Society. (2014). Growth charts for Canada. Retrieved from cps.ca
Public Health Agency of Canada. (2014). WHO Growth Charts Adapted for Canada.
Melmed, S., et al. (2019). Williams Textbook of Endocrinology. 14th Edition. Elsevier.
Medical Council of Canada. (2023). MCCQE Part I Objectives: Endocrinology.
UpToDate. (2024). Diagnostic approach to children and adolescents with short stature.
Toronto Notes. (2024). Pediatrics: Endocrinology Section.