Decreased Activity Level - Case 2-2: 2-Week-Old Boy
Decreased Activity Level - Case 2-2: 2-Week-Old Boy: Excerpt from Pediatric Complaints and Diagnostic Dilemmas
I. History of Present Illness
A 16-day-old male infant presented to the emergency department with a 24-hour
history of decreased level of activity. Breast-feeding had not been going well
since birth, but he had been breast-feeding even less than usual for the past
several days. The infant received cow
's milk-based formula supplementation 2 days before presentation because of the
difficulty with breast-feeding. The incident that prompted the emergency
department visit was a 2-second choking episode during a feed. The incident
occurred at the beginning of the feed, and the infant
's eyes appeared to “roll into the back of his head.” The parents denied tonic-clonic or jerking activity and color change, although
the child was less active after this episode. The infant had had decreased
urine output, with only one wet diaper in the preceding 24 hours.
II. Past Medical History
This infant was born after 36 weeks of gestation, the fourth child of a
28-year-old mother. The pregnancy was complicated by preterm labor, and the
mother received magnesium tocolysis. At 36 weeks, the magnesium was stopped and
labor was allowed to progress. Delivery was uncomplicated. Maternal prenatal
laboratory and culture results were reportedly normal. The child was discharged
from the hospital on the second day of life.
III. Physical Examination
T, 37.5°C; RR, 32/min; HR, 142 bpm; BP, 95/65 mm Hg
Weight and height, 5th percentile
On examination, he appeared awake but hypotonic. He was thin-appearing and cried
only with stimulation. His anterior fontanel was sunken, and his lips and
mucous membranes were dry. He had decreased tear production. His lungs were
clear. The cardiac examination revealed a normal rate and rhythm without any
murmur or abnormal heart sounds. His abdomen was soft without any organomegaly.
His extremities were cool, with a 2-second capillary refill time. Both
testicles were descended. His neurologic examination revealed no focal
abnormalities.
IV. Diagnostic Studies
The WBC count was 16,300 cells/mm3, with 38% segmented neutrophils, 54% lymphocytes, and 6% monocytes. The
hemoglobin was 18.2 g/dL. The platelet count was 658,000/mm
3. The results of the basic metabolic panel revealed the following: sodium, 115
mEq/L; potassium, 7.7 mEq/L; chloride, 81 mEq/L; bicarbonate, 16 mEq/L; blood
urea nitrogen, 31 mg/dL; creatinine, 1.0 mg/dL; glucose, 89 mg/dL; and calcium,
10.7 mg/dL. The serum ammonia level was 39
µg/dL. Lumbar puncture revealed 1 WBC/mm3. The cerebrospinal fluid (CSF) glucose and protein concentrations were normal.
Cultures of CSF, blood, and urine were obtained.
V. Course of Illness
The infant was treated with ampicillin and cefotaxime empirically due to his ill
appearance. He was admitted to the neonatal intensive care unit for further
evaluation. Careful consideration of the laboratory findings suggested a
diagnosis.
Discussion: Case 2-2
I. Differential Diagnosis
Hyponatremia with hyperkalemia in a 2-week-old infant is most concerning for
congenital adrenal hyperplasia (CAH). Other causes of electrolyte abnormalities
in a young infant include water intoxication, gastroenteritis, and
inappropriate formula preparation. If an ill-appearing infant presents
primarily with vomiting, pyloric stenosis and malrotation should be included in
the differential diagnosis. The choking incident provided in the history could
also indicate an episode of gastroesophageal reflux or a seizure.
II. Diagnosis
The laboratory pattern was consistent with CAH. Additional laboratory evaluation
revealed a markedly increased concentration of 17-hydroxyprogesterone (greater
than 120,000 ng/dL; normal range, 4 to 200 ng/dL), which is a precursor for
21-hydroxylase enzyme. Additionally, the concentration of corticotropin (ACTH)
was markedly elevated at 541pg/ml (normal range, 9 to 52). This child is a male
infant who is presenting with a salt-wasting form of CAH.
The diagnosis is 21-hydroxylase deficiency.
III. Incidence and Epidemiology
The adrenal gland is responsible for the production of three categories of
steroids: mineralocorticoids, glucocorticoids (cortisol), and androgens
(dehydroepiandrosterone, androstenedione, 11-
β-hydroxyandrostenedione, and testosterone). CAH is a category of autosomal
recessive disorders that result in deficiency of an enzyme necessary for
cortisol synthesis. Depending on the location of the blockade, excesses or
deficiencies of the mineralocorticoids and androgens can occur.
Cortisol deficiency results in increased production of ACTH by the anterior
pituitary gland and subsequent hyperplasia of the adrenal cortex. Severity of
illness depends on the severity of the genetic mutation. The incidence of CAH
ranges from 1 in 5,000 to 1 in 15,000 live births. Although several enzyme
deficiencies can result in CAH, 90% to 95% of cases are due to lack of
21-hydroxylase, and 4% are due to 11-
β-hydroxylase deficiency. Other rare enzyme defects that have been described
include 3-
β-hydroxysteroid dehydrogenase deficiency, 17-α-hydroxylase deficiency, and cholesterol side chain cleavage enzyme deficiency.
IV. Clinical Presentation
There are several clinical forms of presentation for CAH. Androgen excess
results in virilization. In the female, there is usually some degree of
clitoromegaly and labial fusion, but the female internal genital organs are
normal. Mineralocorticoid deficiency results in an inability to exchange
potassium for sodium in the distal tubule of the nephron; hence, there is
sodium loss in the urine and an inability to secrete potassium. This
electrolyte abnormality is referred to as salt wasting. Patients with the
salt-wasting type of CAH become symptomatic shortly after birth. They have
progressive weight loss, dehydration, and vomiting. If the condition is not
recognized, death occurs within a few weeks.
Girls with virilization tend to be diagnosed at birth due to their ambiguous
genitalia. Boys may be diagnosed at 1 to 2 weeks of life if they present with a
salt-wasting type of CAH or at about 4 years of age if they present with
premature development of secondary sexual characteristics.
The two most common forms of CAH, 21-hydroxylase deficiency and 11-β-hydroxylase deficiency, result in virilization. Approximately 75% of the
21-hydroxylase deficiencies also cause salt wasting; however, 25% of patients
present with virilization alone. Patients with 11-
β-hydroxylase deficiency do not have salt wasting, but they develop hypertension
after the first few years of life.
The 3-β-hydroxysteroid dehydrogenase defect causes salt wasting and mild virilization.
Patients with the cholesterol side chain cleavage enzyme defect present with
salt wasting and female phenotype.
V. Diagnostic Approach
There are several tests to assess for CAH.
Serum electrolytes. Hyponatremia and hyperkalemia, although not diagnostic, are often the laboratory
abnormalities that prompt further investigation.
Other studies. In classic 21-hydroxylase deficiency, serum levels of 17-hydroxyprogesterone
are markedly elevated. Interpretation of 17-hydroxyprogesterone levels in
neonates is difficult, because this hormone may be increased in sick or
premature infants and also in healthy infants during the first 2 days of life.
Cortisol levels are typically low in patients with the salt-wasting variety and
normal in patients with virilization. In 11-hydroxylase deficiency, the levels
of 11-deoxycorticosterone and 11-deoxycortisol are increased. The 3-
β-hydroxysteroid dehydrogenase defect causes levels of 17-hydroxypregnenolone as
well as 17-hydroxyprogesterone to be elevated and hence may be confused with
21-hydroxylase deficiency.
VI. Treatment
Administration of glucocorticoids inhibits excessive production of androgens.
The most frequently recommended glucocorticoid is hydrocortisone administered
orally. Dosages should be individualized based on growth and hormone levels.
The administration of exogenous glucocorticoids continues indefinitely.
Children with CAH require higher doses of glucocorticoids during periods of
stress, such as illness, infection, or surgery.
If the patient also has salt wasting, then mineralocorticoid replacement and
sodium supplementation are also required. Florinef (9-
α-fluorocortisol) is the currently recommended mineralocorticoid.
Determination of the sex of a neonate with ambiguous genitalia is important. If
a girl has clitoromegaly, surgical correction can reposition the clitoris under
the pubis to achieve a more normal appearance. Because CAH is an autosomal
recessive disorder, it is important to test siblings of affected patients.
VII. References
1. Laue L, Rennert OM. Congenital adrenal hyperplasia: molecular genetics and
alternative approaches to treatment.
Adv Pediatr 1995;42:113–143.
2. Lim YJ, Batch JA, Warne GL. Adrenal 21-hydroxylase deficiency in childhood:
25 years
' experience. J Paediatr Child Health 1995;31:222–227.
3. White PC, New MI, Dupont B. Congenital adrenal hyperplasia [first of two
parts].
N Engl J Med 1987;316:1519–1524.
4. White, PC, New, MI, Dupont, B. Congenital adrenal hyperplasia [second of two
parts].
N Engl J Med 1987;316:1580–1586.
Book Source Details
- Book Title: Pediatric Complaints and Diagnostic Dilemmas
- Author(s): Samir S Shah MD; Stephen Ludwig MD
- Year of Publication: 2003
- Copyright Details: Pediatric Complaints and Diagnostic Dilemmas, Copyright © 2003 Lippincott Williams & Wilkins.
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