Pediatric Examination and Board Review (68 page)

10.
(E)
Maturity-onset diabetes of youth. Maturityonset diabetes of youth is a rare group of disorders with characteristics of type 2 diabetes mellitus caused by monogenic defects of beta cell function. Clinical criteria include the onset of type 2 diabetes at an early age (<25 years of age) and autosomal dominant inheritance.

11.
(D)
Several hours after the institution of therapy. Cerebral edema is usually not seen until the patient has been treated with fluids and insulin and laboratory data have shown improvement.

12.
(A)
Tachycardia. Manifestations of cerebral edema include headache, deepening coma, fever, bradycardia, widened pulse pressure, papilledema, and unequal pupils. The exact cause of cerebral edema is still controversial, but it is likely related to overtreatment with hypotonic solutions and rapid changes in plasma osmolality.

13.
(B)
Stop insulin therapy. A decrease of IV fluids, mannitol administration, and hyperventilation are all appropriate measures to decrease intracranial pressure to avoid brain herniation. Insulin therapy would still be indicated to correct the metabolic state.

14.
(B)
Check urine ketones. Children with diabetes are prone to develop DKA in times of illness because of the secreted stress hormones associated with illness (see question 4), which makes them relatively insulin resistant. Furthermore, the production of ketones can be the result of gastroenteritis or can cause a child to feel ill and vomit. If the child does have ketones, holding the insulin will make the situation worse, and additional insulin is required to reverse the catabolic state. Although pushing fluids is important in children who are vomiting to prevent dehydration, determination of urine ketone status is the most important first step in caring for this child.

15.
(E)
Administer glucagon. Glucagon will rapidly increase the blood sugar and get the child to a point where he or she is conscious enough to ingest oral glucose. Nothing should be put into the mouth of a seizing child to avoid aspiration. Depending on the cause of the hypoglycemia, the child may need an adjustment to the insulin dose.

16.
(B)
Poor compliance. Weight loss and an elevated hemoglobin A1c in a diabetic suggest foremost a deficiency of insulin. Unfortunately, it is not uncommon to detect poor compliance in an adolescent with diabetes. The hemoglobin A1c measures how much glucose is irreversibly bound to hemoglobin and thus is a marker of blood sugar levels over the last 3 months (lifespan of red blood cells).

17.
(E)
Hyperinsulinism. Acanthosis nigricans is characterized by hyperpigmented, thick, velvety lesions that occur most commonly on the posterior neck, groin, and axilla. It is commonly seen in obese patients who have insulin resistance.

18.
(D)
C-peptide. C-peptide is generated from the cleavage of proinsulin, and one molecule of C-peptide is released into the circulation for every molecule of insulin. Thus C-peptide can be used as an index of insulin secretion. C-peptide levels are generally low in type 1 diabetes associated with insulin deficiency and normal to high in type 2 diabetes associated with insulin resistance.

S
UGGESTED
R
EADING

Cooke DW, Plotnick L. Type 1 diabetes mellitus in pediatrics.
Pediatr Rev.
2008;29:374-385.

Cowell KM. Type 2 diabetes mellitus.
Pediatr Rev.
2008;29:289-292.

Sperling MA, Weinzimer SA, Tamborlane WV. Diabetes mellitus. In: Sperling MA, ed.
Pediatric Endocrinology.
3rd ed. Philadelphia, PA: WB Saunders; 2008:374-421.

CASE 43: A NEONATE WITH AMBIGUOUS GENITALIA

You are called to the newborn nursery emergently to see a full-term baby with ambiguous genitalia. The pregnancy and delivery were unremarkable. On physical examination, the baby is in no distress. The baby has a phallus that is 2 cm in stretched length. There is a 1-mm orifice at the base of the phallus, no obvious vaginal opening, and no palpable gonads (
Figure 43-1
).

FIGURE 43-1.

SELECT THE ONE BEST ANSWER

1.
If the karyotype is 46,XX, what would be the most likely diagnosis?

(A) maternal androgen exposure

(B) ovotesticular disorder of sex development (DSD)

(C) congenital adrenal hyperplasia (CAH)

(D) 5-alpha-reductase deficiency

(E) gonadal dysgenesis

2.
Which of the following is the most frequent enzymatic defect in congenital adrenal hyperplasia?

(A) 3-beta-hydroxysteroid dehydrogenase deficiency

(B) 11-beta-hydroxylase deficiency

(C) 21-hydroxylase deficiency

(D) 17-hydroxylase deficiency

(E) steroidogenic acute regulatory protein (StAR) deficiency

3.
What would your immediate concern be for the baby in question 1?

(A) hypokalemia

(B) surgical correction of the genital abnormality

(C) assigning a sex

(D) renal anomalies

(E) possibility of salt-wasting crisis

4.
You diagnose the patient with CAH as a result of 21-hydroxylase deficiency. What are the mother’s chances of having another baby with CAH?

(A) Less than 5%

(B) 25%

(C) 50%

(D) 75%

(E) 100%

5.
Which of the following is measured as part of the newborn screen to detect CAH?

(A) 17-hydroxyprogesterone

(B) 17-hydroxypregnenolone

(C) 21-hydroxylase

(D) testosterone

(E) androstenedione

6.
What would be the most likely diagnosis if the baby has palpable gonads, a phallic urethra, and also has other midline defects such as cleft lip and palate?

(A) CAH

(B) panhypopituitarism

(C) ovotesticular DSD

(D) androgen insensitivity syndrome

(E) 5-alpha-reductase deficiency

7.
The initial evaluation of an infant with ambiguous genitalia should include which of the following?

(A) karyotype, abdominal radiograph, measurement of adrenal steroids

(B) pelvic ultrasound, measurement of adrenal steroids, biopsy of gonads

(C) karyotype, measurement of adrenal steroids, biopsy of gonads

(D) karyotype, abdominal radiograph, measurement of sex steroids

(E) karyotype, pelvic ultrasound, measurement of adrenal steroids

8.
Which of the following disorders does not usually have associated external genital abnormalities?

(A) Smith-Lemli-Opitz syndrome

(B) Prader-Willi syndrome

(C) Turner syndrome

(D) trisomy 18

(E) B and C

9.
What is the role of the sex-determining region Y (SRY) chromosome?

(A) initiate external male genitalia formation

(B) initiate testis formation

(C) inhibit formation of internal female genitalia

(D) inhibit formation of external female genitalia

(E) initiate ovarian formation

10.
5-alpha-reductase has what function?

(A) converts testosterone into estradiol

(B) converts testosterone into dihydrotestosterone

(C) converts dihydrotestosterone into testosterone

(D) converts estradiol into testosterone

(E) converts androstenedione into testosterone

11.
Abnormalities in which of the following genes lead to abnormalities in sexual differentiation?

(A) sex-determining region on the Y chromosome

(B) 5-alpha-reductase