Pediatric Endocrinology

Negative feedback loop

Endocrine gland releases hormone --> target gland releases secondary hormone which feeds back to decrease its own production if there is too much of it by decreasing the production of the initial hormone by the endocrine gland

3 components of the endocrine system

Cells that send hormones

Target cells that receive hormones

Hormones

What does the endocrine system regulate?

Energy production, metabolism G&D, F&E balance, stress response, and sexual development

Hormones

Spread through blood, lymph, and ECG

Widespread, long lasting effects

Endocrine master gland

Pituitary gland

Hormones released by the anterior pituitary

GH, ACTH, TSH, FSH, LH

GH

Affects bone

ACTH

Affects adrenal cortex

TSH

Affects thyroid

FSH & LH

Affects testes and ovaries

Hormones released by the posterior pituitary

ADH and oxytocin

ADH

Affects kidney

Oxytocin

Affects mammary glands and uterus

Endocrine control center

Hypothalamus --> links nervous system and endocrine system

What does the hypothalamus send out?

Releasing hormones to the pituitary gland

Releasing hormones sent to the pituitary by the hypothalamus

Gonadotropin-releasing hormone (GnRH)

Thyroid releasing hormone (TRH)

Corticotropin releasing hormone (CRH)

Growth hormone releasing hormone (GHRH)

Thyroid loop in BMR Regulation

1. Hypothalamus sends TRH to anterior pituitary

2. Anterior pituitary sends TSH to the thyroid

3. Thyroid produces T3 & T4

If the thyroid gland produces excess T3 & T4...

The excess T3 & T4 inhibit the release of TRH by the hypothalamus and TSH by the pituitary

T3 & T4 role

Affects BMR, regulates growth & tissue differentiation

What is required for the production of T3 & T4?

Iodine is required to produce

Hypothyroidism

Too little T3 and T4

Hyperthyroidism

Too much T3 & T4

Thyroid dysfunction may be d/t...

A disturbance in TSH secretion from the anterior pituitary

What else is produced by the thyroid gland?

Calcitonin -- promotes bone health

Juvenile hypothyroidism

One of most common endocrine problems of early childhood

Characterized by slow growth & lack of activity

Types of juvenile hypothyroidism

Congenital & acquired

Discovery of congenital juvenile hypothyroidism

Discovered on newborn screen (NBS) for metabolic d/o as an infant

Patho of congenital juvenile hypothyroidism

Insufficient hormone secretion from thyroid gland

Complications of congenital juvenile hypothyroidism

Neurocognitive dysfunction if untreated

S/Sx of congenital juvenile hypothyroidism

Poor feeding, jaundice, large fontanelle

Onset of acquired juvenile hypothyroidism

Occurs after the newborn period

Causes of acquired juvenile hypothyroidism

May be caused by thyroidectomy, thyrotoxicosis, radiation, Hodgkin's lymphoma, dietary iodine insufficiency (rare)

S/Sx of acquired juvenile hypothyroidism

Poor growth, myxedematous skin changes, cold intolerance, fatigue, constipation, mental decline, delayed puberty, irregular menses

Myxedematous skin changes in acquired juvenile hypothyroidism

Dry skin, sparse hair, periorbital edema

Hormone levels in juvenile hypothyroidism

T3 & T4 levels would be decreased, TSH levels would be increased

Tx of juvenile hypothyroidism

Thyroid replacement therapy --> levothyroxine (Synthroid)

Admin considerations with Synthroid

Crush in breastmilk/formula

Cannot be given w/ soy formula, antacids, iron

Food impacts absorption

Adrenal gland loop

1. Hypothalamus sends CRH to anterior pituitary

2. Anterior pituitary sends ACTH to the adrenal cortex

3. Adrenal cortex releases steroids

Types of steroids released by the adrenal cortex

Glucocorticoids, mineralocorticoids, sex steroids

Glucocorticoids

Cortisol

Mineralocorticoids

Aldosterone

Sex steroids

Androgens, estrogens, progestins

Most common cause of adrenal insufficiency in children

Congenital adrenal hyperplasia (CAH)

CAH

Enlarged adrenal glands at birth, detected in NBS

Adrenal cortex in CAH

There is less cortisol & aldosterone & an overproduction of androgens to compensate

S/Sx of CAH

Poor weight gain & poor feeding in infants

Ambiguous genitalia d/t increased androgens

Therapy for CAH

Steroids to suppress androgen production, lab testing

Fever/infection in CAH

Adrenal cortex cannot produce cortisol to fight infections --> medical emergency requiring hospitalization and IV management

Gonad loop

1. Hypothalamus sends GnRH to the anterior pituitary

2. Anterior pituitary sends FSH & LH to the gonads

3. Gonads secrete estrogen & testosterone

Growth hormone (GH)

Required for bone growth, muscle/strength, and fat

Types of growth hormone deficiency (GHD)

Congenital, acquired (radiation, tumor), or idiopathic

Course of GHD

Normal growth for first year, then slowed growth <3rd% after first year

S/Sx of GHD

Stunted growth w/ normal nutritional appearance

Sexual development delays common

Testing for GHD

MRI, bone age testing, genetic testing, blood work, GH stimulation test

Dx of GHD

Poor growth on growth charts, abnormal GH stimulation test, and delayed bone age

Bone age & GHD

Helps to assess skeletal maturity, bones are younger than chronological age in GHD d/t not enough growth hormone

Bone age test for GHD

XR that compares age of bone in left hand to chronological age

Tx for GHD

GH replacement via SQ injection, tumor concerns

Timing of puberty

8-12 y/o for females

9-14 y/o for males

Manifestations of puberty in females

Begin with thelarche (breast budding) & pubic hair

Growth spikes early in puberty

Manifestations of puberty in males

Increase in testicular size, growth spikes later in puberty

Course of puberty in females & males

2-5 years for completion

50% of adult weight gained

20% of adult height achieved

Precocious (early) puberty

Secondary sex characteristics before 9 in boys, before 8 in girls

Types of precocious puberty

Central and peripheral

Most common form of precocious puberty

CPP (central), GnRH released from hypothalamus

Causes of CPP

Congenital, trauma, neoplastic, or idiopathic causes

> 90% w/ no determined cause

Epidemiology of CPP

Common in girls

PPP

Variations within development

Dx of precocious puberty

Blood work, bone age study

Tx of precocious puberty

GnRH antagonists that inhibit FSH and LH

Risks w/ precocious puberty

Increased risk of high risk behavior and mental health concerns

Types of incomplete puberty

Premature thelarche & premature adrenarche

Premature thelarche

Transient, no other signs of development (pubic hair, etc.)

Premature adrenarche

Occurs at 6-8 years, body odor, pubic hair, & axillary hair develop but there is no thelarche or testicular enlargement

Delayed puberty in females

No breast buds by 13 years OR no menarche by 16/no menses after 4 years of breast development

Delayed puberty in males

No testicular enlargement by 14 years or no pubic hair by 15 years/more than 5 years between initiation of puberty signs and genital growth

Considerations w/ delayed puberty in males

Chronic dz considerations

Diagnosis and tx of delayed puberty

Diagnosis of exclusion, tx is based on diagnosis & considerations

Diabetes insipidus is a...

D/o of the posterior pituitary gland

Diabetes insipidus (DI)

Under-secretion of ADH/vasopressin --> uncontrolled diuresis, excess thirst & water intake

Dx of DI

MRI & water deprivation test

Types of DI

Primary & secondary

Primary DI

Usually idiopathic (20-50%) or familial

Secondary DI

Tumors, infections, trauma, granulomatous disease, certain drugs, loss of blood flow to the pituitary

First signs of DI

Enuresis, polyuria, polydipsia

S/Sx of DI in infants

Only soothed by water, not breast milk or formula

Dehydration & electrolyte imbalances

Labs in DI

High serum osmolality, low urine osmolality & specific gravity

Course of DI

May be temporary or permanent

Other s/sx of DI

Up to 20L or urine per day

Hypovolemia, tachycardia, hypotension

Nursing care for kids with DI

Monitor & replace fluids, neuro status, VS, check mucous membranes

Tx for DI

Daily synthetic ADH (DDVAP)/Vasopressin either nasally or PO

Medical alert bracelet, school considerations

Water deprivation test involves...

A fluid restriction

Normal water deprivation results

Decreased fluid intake = reduced urine output, increased urine concentration

Water deprivation test results in a patient w/ DI

No effect on urine formation or osmolality

Nursing actions during a water deprivation test

Strict monitoring of fluid intake & UO

Urine concentration measurements w/ each void

Serum osmolality q2h

Hourly weight & BP checks

Weight loss during water deprivation test

Weight loss between 3-5% indicates dehydration & end of test

Actions following a positive water deprivation test

Test dose of DDAVP to assess symptom alleviation

Role of insulin in the body

Supports metabolism for carbs, fats, and proteins by being the key for glucose into muscle & fat cells

It also helps store glucose as glycogen in liver and muscle

Insulin in diabetes mellitus

Decreased insulin secretion or insulin resistance --> glucose cannot enter cells, body is in starvation mode

Impact of insulin dysfunction in DM on glucose levels

Glucose builds up in bloodstream --> hyperglycemia