Pediatric Examination and Board Review (118 page)

A 15-year-old boy is brought in to the teen clinic for evaluation of short stature. Records provided by his previous pediatrician indicate that he had been growing along the 5th percentile for height and weight until a year ago. During the past year he has grown approximately 6 cm. He is upset about being the shortest in his class and also worried about his acne and the “bumps” he recently found in his breasts.

His mother states he was born after a full-term, uncomplicated pregnancy. His birth weight was 3000 g (6 lb, 10 oz). Delivery was normal. He attained all his early developmental milestones on time. At age 18 months he was hospitalized for acute diarrhea and dehydration. His past medical history is otherwise unremarkable and the family history is noncontributory. His mother is 5'2" and his father is 5'10". The patient is an average student and has several good friends. The review of systems is negative.

On physical examination he is a pleasant, slender young man with no evidence of dysmorphism. He is 5'1" (5th percentile) and weighs 105 lb (10th percentile). His BMI is 19.5 (8th percentile). He has mild facial acne and slight bilateral gynecomastia. His genital development is at Tanner stage 3. His testicular volume is 8 mL, bilaterally. The rest of the examination shows no abnormalities.

SELECT THE ONE BEST ANSWER

1.
What is the most likely diagnosis in this case?

(A) acquired hypothyroidism

(B) vitamin deficiency

(C) Klinefelter syndrome

(D) constitutional delay of puberty

(E) growth hormone (GH) deficiency

2.
What other clinical information will you need to assess this problem?

(A) dietary history

(B) time at onset and tempo of pubertal changes

(C) adult height and growth and pubertal development patterns of all first- and second-degree relatives

(D) history of medication intake

(E) all of the above

3.
What is this adolescent’s mid-parental height?

(A) 5'6" (168 cm)

(B) 5'7
¹
/
₂
" (171 cm)

(C) 5'8
¹
/
₂
" (174 cm)

(D) 5'9" (175 cm)

(E) 5'10" (178 cm)

4.
According to his mid-parental height, what would be this young man’s target height?

(A) 5'5"-5'7" (165-170 cm)

(B) 5'6"-5'9" (168-175 cm)

(C) 5'4
¹
/
₂
"-5'10" (164-178 cm)

(D) 5'5"-6'0" (165-183 cm)

(E) 5'5"-5'9
¹
/
₂
" (165-176 cm)

5.
Which of the following elements of the physical examination will be the least valuable in the initial evaluation of this condition?

(A) evaluation of visual acuity

(B) sexual maturity rating

(C) sense of smell

(D) thyroid examination

(E) arm span and upper/lower segment ratios.

6.
What tests, if any, would help in the initial evaluation of this patient?

(A) no tests are needed at this time

(B) complete blood count (CBC), urinalysis, complete metabolic panel including glucose, calcium, phosphorus, kidney, and liver function tests

(C) CBC, urinalysis, thyroid function tests, bone age

(D) CBC, urinalysis, erythrocyte sedimentation rate, complete metabolic panel including glucose, calcium, phosphorus, kidney and liver function tests, luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone, thyroid-stimulating hormone (TSH), prolactin, and bone age

(E) somatomedin C and karyotype

7.
Concerning bone age, which of the following statements is false?

(A) delayed bone age occurs in adolescents with chronic illness, hypothyroidism, and hypopituitarism

(B) in patients with constitutional delay of puberty, the bone age equals the chronological age

(C) a bone age study provides clues for potential future linear growth

(D) in familial short stature, the bone age is advanced in relation to the height age

(E) in patients with constitutional delay of puberty, the bone age equals the height age

8.
Bone maturation is controlled by

(A) adrenal androgens

(B) estrogens

(C) thyroid hormones

(D) testosterone

(E) all of the above

9.
Pubertal linear growth accounts for what percentage of final height?

(A) 10-15%

(B) 15-20%

(C) 20-25%

(D) 25-30%

(E) more than 30%

10.
During peak height velocity, the average linear growth in boys is

(A) 6 cm/year

(B) 8 cm/year

(C) 10 cm/year

(D) 13 cm/year

(E) 15 cm/year

11.
Which of the following statements is false?

(A) peak height velocity occurs about 18-24 months earlier in girls than in boys

(B) most linear growth occurs in boys during Tanner stages 3-4

(C) testicular growth is usually the earliest sign of pubertal development

(D) menarche usually happens during Tanner stage 2

(E) most linear growth occurs in girls before Tanner stage 3

12.
The mean age of onset of puberty in boys is

(A) 11.6 years

(B) 12.5 years

(C) 13.2 years

(D) 14.0 years

(E) 14.5 years

13.
Which of the following is not a normal finding in adolescent boys?

(A) gynecomastia during sex maturity rating (SMR) 3

(B) testicular size of 4.0 mL during SMR 4

(C) attainment of SMR 3 before peak height velocity

(D) asymmetric gynecomastia

(E) facial acne at age 12 years

14.
Which of the following statements concerning constitutional delay of puberty (CDP) is false?

(A) CDP is a diagnosis of exclusion

(B) a family history of CDP is usually present

(C) most delayed puberty in boys is constitutional

(D) in CDP, bone age is delayed in relation to chronological age and typically corresponds to height age

(E) absence of any sign of puberty in a boy after the age of 12.5 years merits investigation

15.
The BMI seems to play an important role in the onset of pubertal changes. What percentage body fat is typically needed to reach menarche?

(A) 8%

(B) 17%

(C) 22%

(D) 25%

(E) 30%

16.
All of the following are consistent with the diagnosis of CDP except

(A) negative detailed review of systems and evidence of adequate nutrition

(B) linear growth velocity less than 3.7 cm/year during the previous year

(C) normal findings on physical examination, including genital anatomy, sense of smell, and upper to lower body segment ratio

(D) normal CBC, electrolyte, blood urea nitrogen (BUN), and sedimentation rate

(E) delayed bone age

17.
All of the following are characteristic of early adolescence except

(A) concrete thought

(B) inability to perceive long-term consequences of current decisions and acts

(C) limited dating

(D) development of a sense of omnipotence and invincibility

(E) emergence of sexual feelings

ANSWERS

1.
(D)
In evaluating a child with short stature, the first step is to determine the patient’s growth and developmental pattern. In this case, the growth chart indicates that he has always grown along the 5th percentile for height and weight. He has gained 6 cm during the past year indicating that, even though he has not grown to the extent expected during the growth spurt (8-14 cm/year), there has been continuous, linear growth. From his sexual maturity rating (Tanner 3) we can infer that he probably has not attained peak height velocity yet but that puberty is underway. Because there are no dysmorphic features, and there is an otherwise normal history, review of systems, and examination, familial short stature and CDP would be the 2 most common conditions to explain this patient’s presentation. Because his mid-parental height allows us to predict a normal final height, CDP would be the most likely diagnosis in this case. Acquired hypothyroidism would typically present with a pattern of attenuated or stunted linear growth, increased tiredness, weight gain, cold intolerance and dry skin, none of which are present in this patient. Klinefelter syndrome (47,XXY), the most frequent cause of primary hypogonadism, would also be unlikely. Phenotypic abnormalities in this condition include relatively long arms and legs, decreased virilization, and small firm testes leading to severely subnormal sperm counts and infertility. Behavioral changes may also be present. GH deficiency and other endocrine disorders that affect linear growth are usually associated with an increased weight-toheight ratio. In many cases, however, it may be difficult to distinguish GH deficiency from constitutional delay of puberty solely on clinical grounds, and a full endocrinology workup will be needed to confirm the diagnosis.

2.
(E)
The single most useful tool in the evaluation of a teenager with growth retardation is a thorough clinical evaluation. Data gathering should include a complete review of systems, a detailed description of linear growth patterns, and pubertal changes correlated with time, diet and exercise history, previous illnesses, medication, congenital abnormalities, headaches, visual disturbances, and anosmia. Information about growth and development patterns and adult height of first- and second-degree relatives should be obtained. Accurate serial measurements of height and determination of height velocity are fundamental components of the diagnostic workup.

3.
(C)
His mid-parental height is 5'8
¹
/
₂
". The midparental height is calculated in boys by adding 5 inches (13 cm) to the maternal height and averaging it with the paternal height. For girls, the midparental height equals the paternal height minus 5 inches averaged with maternal height.

4.
(D)
His target height would be 5'5"-6'0" (165-183 cm). The target height equals the mid-parental height ± 2 standard deviations (SD). Each SD equals 1.67 inches (4.25 cm).