DNB Pediatrics FAQ 2 – CAH

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Author for this post Shailesh Gophane is DCH from J.J.  Hospital, Mumbai and DNB from Port Trust Hospital Mumbai. Over to him.....

“ This is a series of Notes for dnb pediatrics theory exams. Definitely they  are not the alternative to reading Nelson's thoroughly, but these notes will  prove helpful during final days of revision and may be helpful to overcome any  loopholes if you are not having enough time to cover whole system. " December 2015  had 6 repeat questions from these notes.

FAQ 2:
Clinical featers and management of a child with congenital adrenal hyperplasia.


Congenital adrenal hyperplasia (CAH) is a family of autosomal recessive disorders of cortisol biosynthesis. Cortisol deficiency increases secretion of corticotropin (ACTH), which in turn leads to adrenocortical hyperplasia and overproduction of intermediate metabolites.

Depending on the enzymatic step that is deficient, there may be signs, symptoms, and laboratory findings of mineralocorticoid deficiency or excess; incomplete virilization or premature puberty in affected males; and virilization or sexual infantilism in affected females.

More than 90% of congenital adrenal hyperplasia (CAH) cases are caused by 21-hydroxylase deficiency.

Its clinical features are described below:

1) Cortisol and aldosterone deficiency 

Progressive weight loss, anorexia, vomiting, dehydration, weakness, hypotension, hypoglycemia, hyponatremia, and hyperkalemia. These problems typically 1st develop in affected infants at approximately 10-14 days of age. Without treatment, shock, cardiac arrhythmias, and death may occur within days or weeks.

2) Prenatal androgen excess

This problem begins in affected fetuses by 8-10 wk of gestation and leads to abnormal genital development in females. This manifests as labial fusion, clitoromegaly, urogenital sinus, Sexually dimorphic behavior (Masculine play with decreased interest in maternal roles).

3) Post natal androgen excess

Rapid somatic growth and accelerated skeletal maturation (tall in childhood with stunted adult stature). Excess muscular development, pubic and axillary hair, enlarged penis with relatively small testes).

4) Adrenomedullary dysfunction

Blunted epinephrine responses, decreased blood glucose and lower heart rates with exercise.

Management:

I) Investigations:

1) Serum electrolytes - hyponatremia, hyperkalemia, metabolic acidosis.
2) Blood sugar – Hypoglycemia
3) Elevated 17 (OH) progesterone
4) Low serum cortiosl
5) Elevated renin with inappropriately low serum aldosterone
6) USG abdomen and pelvis to look for internal genital organs ( Ovaries and uterus) in phenotypic females.
7) Karyotyping.
8) Prenatal diagnosis – DNA analysis for CYP21 gene.
9) Newborn screening – 17 (OH) progesterone levels in heel prick dried blood samples.

II) Treatment:

1) Glucocorticoid replacement

Typically 15-20 mg/m2/24 hr of hydrocortisone daily administered orally in 3 divided doses. Suppresses excessive production of androgens by the adrenal cortex and thus minimizes problems such as excessive growth and skeletal maturation and virilization.
Stress dose required during periods of stress e.g, infection, surgery.
Monitor growth and pubertal development to adjust the dose.

2) Mineralocorticoid replacement

Required in salt wasting disease. High doses of fludrocortisone, usually 0.1-0.3 mg daily in 2 divided doses but occasionally up to 0.4 mg daily often with sodium supplementation are required.
Serum electrolytes need to monitored initially daily after beginning therapy.

3) Surgical Management of Ambiguous Genitals

Significantly virilized females usually undergo surgery between 2-6 mo of age. If there is severe clitoromegaly, the clitoris is reduced in size, with partial excision of the corporal bodies and preservation of the neurovascular bundle. Vaginoplasty and correction of the urogenital sinus usually are performed at the time of clitoral surgery; revision in adolescence is often necessary.

4) Prenatal treatment

Dexamethasone 20mcg/Kg prepregnancy weight is started at 6 weeks of gestation in at risk pregnancies.
CAH
Chorionic villus biopsy done at 11-12 weeks to confirm sex
CAH pediatrics
Dexa continued till term in a case of a female fetus.


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