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Pediatrics BRS > Chapter 6 - Endocrine > Flashcards

Chapter 6 - Endocrine Flashcards

1
Q

What is considered short stature? What is the difference between normal variant and pathological short stature?

A
  • it is defined as height that is two standard deviations below the mean
  • normal variant short stature is when this is true but the child is still growing with a normal growth velocity
  • pathologic short stature is when the height is two standard deviations below the mean and has suboptimal growth velocity
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2
Q

How is mid-parental heigh calculated?

A
  • for males, MPH = (father’s height + mother’s + 5)/2
  • for females, MPH = (father’s heigh - 5 + mother’s)/2
  • most children end up within 4 inches of their MPH
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3
Q

Name two pharmaceuticals that can lead to short stature if used chronically.

A
  • steroids

- stimulants due to their appetite suppression and possible associated poor weight gain

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4
Q

How is the U/L ratio calculated and what is normal?

A
  • it is the patient’s upper-to-lower body segment ratio
  • calculated with the lower segment being the pubic symphysis to the heel and upper segment being total height minus the lower segment
  • at birth, 1.7 is normal; at 3 years old, 1.3 is normal; and after 7 years old, 1.0 is normal
  • an abnormal U/L suggests a disproportionate short stature
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5
Q

Define the two most common types of normal variant short stature.

A
  • familial: a height at least two standard deviations below the mean with a short MPH but with normal bone age, normal onset of puberty, and minimum growth of 2 inches per year
  • constitutional: a height at least two standard deviations below the mean with a history of delayed puberty in either or both parents, a delayed bone age, late onset of puberty, and a minimum growth of 2 inches per year
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6
Q

How do we classify short stature?

A
  • first as either normal variant or pathologic based on growth velocity
  • then pathological cases are divided as either proportionate or disproportionate based on the U/L ratio
  • proportionate cases can be further divided into cases with a prenatal and postnatal onset
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7
Q

Give the following:

  • two most common types of normal variant short stature
  • four causes of prenatal, proportionate, pathologic short stature
  • seven causes of postnatal, proportionate, pathologic short stature
  • two causes of disproportionate pathologic short stature
A
  • normal variant: familial and constitutional delay
  • prenatal proportionate: environmental causes, chromosomal disorders, genetic syndromes, viral infection
  • postnatal proportionate: malnutrition, cyanotic heart disease, renal disease, GI disease, pulmonary disease, endocrine disease, psychosocial dwarfism
  • disproportionate: rickets or other skeletal dysplasias like achondroplasia
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8
Q

What lab studies are used to investigate pathologic short stature?

A
  • CBC
  • ESR
  • thyroxine
  • electrolytes
  • creatinine and bicarb
  • IGF-1 as an indirect test for GH
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9
Q

Under what circumstances is it acceptable to measure a random growth hormone level?

A

essentially never

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10
Q

List four endocrinopathies that cause short stature.

A
  • growth hormone deficiency
  • hypothyroidism
  • hypercortisolism
  • Turner syndrome
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11
Q

How does bone age help with the differential for short stature?

A
  • it gives information about the potential for further growth
  • if bone age = chronological age, it is suggestive of familial short stature, intrauterine growth retardation, Turner syndrome, or skeletal dysplasia
  • if bone age < chronological age, it is suggestive of constitutional short stature, hypothyroidism, hypercortisolism, GH deficiency, or chronic disease
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12
Q

Growth Hormone Deficiency

A
  • an endocrinopathy which causes a postnatal, proportionate, pathologic short stature; as such that have poor growth velocity and a bone age less than chronological age
  • may be caused by a brain tumor, especially a craniopharyngioma in children under than 5, prior CNS radiation, CNS vascular malformations, autoimmune disease, trauma, or congenital midline defects
  • patients often have a history of prolonged neonatal jaundice, hypoglycemia, cherubic facies, central obesity, microphallus, cryptorchidism, and midline defects
  • imaging studies are used to assess bone age and an MRI is used to rule out CNS lesion
  • labs show low IGF-1 levels and a poor response to GH stimulation testing
  • treated with recombinant GH until bone age shows the patient has reached nearly maximal growth potential
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13
Q

What hormonal event triggers the onset of puberty?

A

a reduction in the overly sensitive nature of the HPG axis to sex steroids at the level of the hypothalamus

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14
Q

Describe normal female puberty.

A
  • begins between 7-13 years of age
  • begins with adrenarche, the onset of adrenal androgen steroidogenesis, which drives the onset of pubic or axillary hair
  • thelarche, the onset of breast development driven by estrogen, however, is usually the first sign of puberty with breast buds forming at an average of 9.5 years old
  • true puberty is defined by an increase in gonadotropins and occurs sometime later
  • menarche begins at 9-15 years of age with an average of 12.5 years old and 2-3 years after thelarche as the HPG axis matures and FSH stimulates ovarian follicle development and estrogen production
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15
Q

Describe normal male puberty.

A
  • begins between 9-14 years of age
  • testicular enlargement is usually the first sign of puberty and occurs between 11-12 years of age, on average
  • FSH then begins stimulating the testes to produce sperm while LH induces production of androgens
  • these androgens are responsible for penile enlargement and the growth of pubic hair
  • those androgens are also responsible for growth of axillary and facial hair, which begins about 2 years after the growth of pubic hair
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16
Q

Which race typically experiences earlier development of sexual characteristics than others?

A

African Americans tend to develop secondary sexual characteristics earlier

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17
Q

How does obesity affect puberty?

A

it is associated with precocity

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18
Q

How do we define precocious puberty?

A
  • for girls, it is thelarche or pubic hair growth before age 7 or menarche before age 9
  • for boys, it is testicular changes, penile enlargement, or pubic or axillary hair growth before age 9
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19
Q

Premature Thelarche

A
  • development of visible or palpable breast tissue only, with no other secondary sex characteristics before age 7
  • quite common and benign, usually presenting within the first 2 years of life due to transient activation of the HPGA
  • requires no workup or treatment
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20
Q

Premature Adrenarche

A
  • growth of pubic or axillary hair without thelarche or testicular enlargement before age 7 in girls and age 9 in boys
  • it is more common in girls and occurs after 5 years of age with pubic and axillary hair growth and apocrine odor; growth is normal and their is no clitoromegaly
  • requires no treatment
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21
Q

Central Precocious Puberty

A
  • the early onset of gonadotropin-mediated puberty due to premature activation of the hypothalamus
  • more common in girls, who tend to have idiopathic cases; in boys sexual precocity tends to be organic and requires evaluation
  • hydrocephalus, CNS infection, cerebral palsy, being hypothalamic hamartomas, malignant tumors, and severe head trauma are all possible causes
  • in contrast to premature adrenarche or thelarche, girls experience breast development, pubic hair growth, and rapid linear growth; similarly boys experience testicular enlargement, pubic hair growth, and rapid linear growth
  • evaluation should include FSH, LH, and sex steroids, a GnRH stimulation test, and an MRI of the head
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22
Q

Peripheral Precocious Puberty

A
  • a precocious puberty that is independent of the HPG axis and instead caused by peripheral production of male or female sex steroids in an FSH/LH-independent manner
  • may be caused by exposure to exogenous sex steroids, gonadal tumors, adrenal tumors, and non classic CAH
  • boys present with either gynecomastia or premature onset of pubic hair; there is usually no testicular enlargement because these patients do not have an increase in FSH but there are some causes that result in testicular enlargement as well
  • girls present with virilization or thelarche
  • the hallmark is a flat response to GnRH stimulation; should also check FSH, LH, testosterone/estradiol levels, and B-hCG
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23
Q

What is the GnRH stimulation test?

A
  • a test to assess whether or not there has been premature activation of the hypothalamus in those with precocious puberty
  • begins with an injection of synthetic GnRH and then measure the LH and FSH response
  • in prepubertal patients or patients with peripheral precocious puberty, there is little rise in LH if any
  • if patients have central precocious puberty (premature activation of the hypothalamus) there will be a dramatic rise in LH
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24
Q

What would cause peripheral precocious puberty in males with testicular enlargement?

A
  • McCune-Albright syndrome
  • Testotoxicosis
  • B-hCG-Secreting Tumors
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25
Q

McCune-Albright Syndrome

A
  • a cause of peripheral precocious puberty with testicular enlargement in males
  • characterized by polyostotic fibrous dysplasia, irregularly bordered hyper pigmented macules (aka coast of Maine cafe-au-lait spots), peripheral precocious puberty, and testicular enlargement
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26
Q

What is testotoxicosis?

A

a disease in which the testes enlarge bilaterally and independently of the HPG axis

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27
Q

What effect do B-hCG-secreting tumors have on puberty?

A

they are unique to males and the B-hCG cross-reacts with LH, stimulating Leydig cells and testicular growth

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28
Q

How do we define delayed puberty?

A
  • as no breast tissue by 13 years of age or no menarche by 14 years of age in girls
  • as no testicular enlargement by age 14 in boys
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29
Q

Hypergonadotropic Hypogonadism

A
  • end-organ dysfunction that leads to a delay of puberty
  • testosterone and estradiol levels are low despite high FSH and LH levels
  • may be caused by chromosomal disorders including Klinefelter syndrome and Turner syndrome or by autoimmune disorders like autoimmune oophoritis associated with Hashimoto’s thyroiditis
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30
Q

Constitutional Delay of Puberty

A
  • due to an immature hypothalamus
  • more common in boys and in those with a family history
  • often associated with constitutional growth delay
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31
Q

Hypogonadotropic Hypogonadism

A
  • delayed puberty secondary to an inactive hypothalamus or pituitary
  • FSH and LH levels are low as are testosterone and estradiol levels
  • may be caused by constitutional delay of puberty, chronic disease, hypopituitarism of any case including brain tumors, prolactinoma, and genetic syndromes such as Kallman syndrome, Prader-Willi syndrome, and Lawrence-Moon Biedl Syndrome
  • the GnRH stimulation test will be flat
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32
Q

What is Kallman syndrome?

A
  • an isolated gonadotropin deficiency associated with anosmia
  • a cause of hypogonadotropic hypogonadism
33
Q

What is Lawrence-Moon-Biedl syndrome?

A
  • a syndrome of obesity, retinitis pigementosa, hypogonadism, and polysyndactyly
  • a cause of hypogonadotropic hypogonadism
34
Q

Describe male development in utero.

A
  • the SRY gene present on the Y chromosome leads to fetal testes
  • these testes have sertoli cells, which produce anti-mullerian hormone
  • they also have Leydig cells, which produce testosterone
  • testosterone stimulates development of the Wolffian ducts but is also converted by 5a-reductase to dihydrotestosterone, which virilizes external genitalia
  • this processes complete by 12 weeks except for penile growth which continues until term
35
Q

Give three possible causes of undervirilized males with ambiguous genitalia?

A
  • inborn errors in testosterone synthesis, including 5a-reductase deficiency
  • gonadal intersex including mixed gonadal dysgenesis (45,XO/46,XY mosaicism, which often manifests as a unilateral streak testis) or true hermaphroditism (both ovarian and testicular tissue, usually from a 46,XX karyotype)
  • partial androgen insensitivity
36
Q

What is the difference between partial and complete androgen insensitivity?

A
  • both are likely to have a 46,XY karyotype
  • however, those with a partial insensitivity have ambiguous genitalia (undervirilized), and those with complete insensitivity are phenotypic females
37
Q

Give three possible causes of ambiguous genitalia in a virilized female.

A
  • CAH caused by 21-OH deficiency is most common
  • virilizing drug used by the mother during pregnancy
  • virilizing tumor in the mother during pregnancy
38
Q

What are three major products of the adrenal cortex?

A
  • mineralocorticoids (aldosterone)
  • glucocorticoids (cortisol)
  • androgens (DHEA)
39
Q

How does mineralocorticoid synthesis by the adrenal cortex differ from that of glucocorticoid and androgen synthesis?

A
  • mineralocorticoid is under the control of the renin-angiotensin system and is independent of the pituitary
  • glucocorticoid and androgen synthesis are regulated by ACTH
40
Q

Acute Adrenal Insufficiency

A
  • a sudden cortisol deficiency
  • most often caused by abrupt withdrawal of glucocorticoids, treatment of Cushing syndrome, or Waterhouse-Friderichsen syndrome
  • presents with weakness and shock
41
Q

Primary Adrenal Insufficiency

A
  • a lack of glucocorticoids caused by destruction of the adrenal cortex or by an enzyme deficiency
  • causes may be congenital or acquired and include Addison’s disease, CAH, and adrenoleukodystrophy
  • presents cortisol deficiency: anorexia, weakness, hyponatremia, hypotension, increased pigmentation
  • and aldosterone deficiency: failure to thrive, salt craving, hyponatremia, hyperkalemia
42
Q

Secondary Adrenal Insufficiency

A
  • a lack of glucocorticoids caused by a process that interferes with the release of CRH or ACTH
  • causes may be congenital or acquired and include pituitary tumors, craniopharyngioma, or iatrogenic from long-term use of glucocorticoids
  • in contrast to primary insufficiency, serum potassium may be normal as there is no aldosterone deficiency
  • and there is no hyperpigmentation because ACTH levels are not elevated
  • presents with only cortisol deficiency: anorexia, weakness, hyponatremia, and hypotension
43
Q

21-Hydroxylase Deficiency

A
  • an autosomal recessive deficiency and the most common cause of CAH
  • typically affects aldosterone and cortisol production, increasing levels of androgens instead
  • classic type (both glucocorticoid and cortisol affected): girls with ambiguous genitalia and both genders experiencing FTT, vomiting, and electrolyte abnormalities
  • simple virilizing (only glucocorticoids affected): girls with ambiguous genitalia, boys with tall stature, advanced bone age, pubic hair, and penile enlargement
  • nonclassic: (glucocorticoids mildly affected): girls with premature adrenarche, clitoromegaly, acne, rapid growth, hirsutism, and infertility; boys with premature adrenarche, rapid growth, and premature acne
  • labs reveal elevated 17-hydroxyprogesterone levels
  • treated with cortisone to suppress ACTH and hyperplasia, mineralocorticoid replacement, and additional steroids during times of stress
44
Q

11B-Hydroxylase Deficiency

A
  • an autosomal recessive cause of CAH, which affects both aldosterone and glucocorticoid production
  • presents with ambiguous female genitalia and other pubertal changes in addition to hypertension and hypokalemia given the accumulation of 11-deoxycorticosterone, a weak mineralocorticoid also known as specific compound S
  • treated with cortisone to suppress ACTH and hyperplasia, control of hypertension, and additional steroids during times of stress
45
Q

3B-Hydroxysteroid Dehydrogenase Deficiency

A
  • an autosomal recessive cause of CAH, which affects production of aldosterone, glucocorticoids, and sex hormones
  • presents with salt-wasting crises, glucocorticoid deficiency, and ambiguous genitalia
  • labs demonstrate elevated DHEA and 17-hydroxypregnenolone levels
  • treat with cortisone to suppress ACTH and hormone replacement
46
Q

Type I Diabetes Mellitus

A
  • an autoimmune condition resulting in insufficient insulin
  • associated with the HLA-DR3 and HLA-DR4 haplotypes although inheritance is multifactorial
  • mediated by a lymphocytic infiltrate of the pancreas, which destroys beta-islet cells; anti-islet cell, anti-insulin, and anti-glutamic acid decarboxylase antibodies may be present but do not mediate disease
  • often presents during the pubertal growth spurt when hormones antagonistic to insulin are elevated
  • present with polyuria, polydipsia, weight loss, and dehydration
  • watch for the “honeymoon” period and the Somogyi phenomenon during management
47
Q

Addison’s Disease

A
  • an acquired chronic adrenal insufficiency resulting from autoimmune destruction, often as a part of autoimmune polyendocrine syndrome in conjunction with Hashimoto’s or T1DM
  • due to a lymphocytic infiltrate although antibodies to the adrenal gland may also be present
  • presents with vague, progressive symptoms of hypotension, weakness, fatigue, n/v, and weight loss
  • assess with an ACTH stimulation test; if cortisol levels double in response to ACTH, this is considered normal
  • treat with IV 5% dextrose in normal saline to correct hypotension and hyponatremia while preventing hypoglycemia
  • begin steroid replacement
48
Q

Cushing Syndrome

A
  • an excess of cortisol
  • causes include exogenous glucocorticoids (most common), an ACTH-secreting pituitary adenoma, ectopic ACTH secretion, or a primary adrenal adenoma/hyperplasia/carcinoma
  • presents with muscle weakness, thin extremities, moon facies, buffalo hump, truncal obesity, abdominal striae, osteoporosis, and immune suppression
  • hypertension with hypokalemia and metabolic alkalosis are also common as cortisol increases the sensitivity of arterioles to sympathetic activity and directly activates aldosterone receptors
  • diagnosed based on a 24-hour urine cortisol level, increased late nigh salivary cortisol level, and poor response to low-dose dexamethasone suppression test
49
Q

Describe the dexamethasone suppression test.

A
  • given in the evening
  • should suppress the following morning’s physiologic rise in cortisol
  • if it doesn’t suppress the rise, then it is indicative of glucocorticoid excess
50
Q

How are the various causes of Cushing’s syndrome differentiated?

A
  • exogenous glucocorticoids: low ACTH, no imaging abnormalities, and bilateral adrenal atrophy (secondary to low ACTH)
  • ACTH-secreting pituitary adenoma: high ACTH, high-dose dexamethasone suppression, pituitary adenoma may be found on imaging, bilateral adrenal growth
  • ectopic-ACTH secretion: high ACTH, no response to high-dose dexamethasone suppression, imaging likely to find a lung cancer, bilateral adrenal growth
  • primary adrenal adenoma: low ACTH, atrophy of the contralateral adrenal gland
51
Q

DKA

A
  • defined as hyperglycemia with ketonuria and a serum bicarb < 15 or pH < 7.3
  • it is an anion gap metabolic acidosis with osmotic diuresis and ketone production
  • pathogenesis involves insulin deficiency, limited cellular availability of glucose despite hyperglycemia, gluconeogenesis plus lipolysis and ketogenesis, dehydration leading to diminished perfusion and lactic acidosis, and osmotic diuresis with loss of electrolytes
  • presents with polyuria, polydipsia, vomiting, diffuse abdominal pain, and fatigue, Kussmaul respirations, and dehydration
  • labs reveal elevated blood glucose, low bicarbonate, low pH, hyperkalemia, elevated anion gap, glucosuria, serum/urine ketones
  • manage with IV isotonic saline bolus to replace intravascular volume; gradually reduce osmolality to minimize the risk for cerebral edema, replace potassium once urine output has been established with either potassium acetate (improves acidosis) or potassium phosphate (improves phosphate depletion and oxygen dissociation from hemoglobin), and administer regular insulin
  • complicated by cerebral edema, severe hypokalemia, and hypocalcemia
52
Q

Congenital Hypothyroidism

A
  • the most common metabolic disorder
  • most commonly caused by thyroid dysgenesis (aplasia or hypoplasia), but can also be caused by inborn errors of thyroid hormone synthesis, use of PTU during pregnancy, and maternal autoimmune thyroid disease
  • most newborns are asymptomatic birth since T4 is not essential for fetal growth; however, they often present with prolonged jaundice, poor feeding, lethargy, constipation, enlarged fontanelles, protruding tongue, umbilical hernia, myxedema, mottled skin, hypothermia, delayed neurodevelopment, and poor growth
  • should be managed with thyroid hormone replacement
53
Q

What is Pendred syndrome?

A

an autosomal recessive inborn error of thyroid hormone synthesis, specifically an organification defect, which causes congenital hypothyroidism associated with sensorineural hearing loss

54
Q

Hashimoto’s Disease

A
  • lymphocytic infiltration and autoimmune destruction of the thyroid gland
  • the most common cause of hypothyroidism worldwide and strongly associated with HLA-DR5
  • may initially present as a hyperthyroidism due to excess release, but there is actually under production, which eventually presents as goiter, short stature with suboptimal growth velocity and delayed bone age, amenorrhea or oligomenorrhea, and myxedema
  • labs find low T4 and elevated TSH
  • antithyroglobulin and anti-thyroid peroxidase antibodies may be present but don’t mediate disease
  • histology reveals chronic inflammation with germinal centers and Hurthle cells
  • increases risk for marginal B-cell lymphoma
55
Q

What is often the first sign of thyroid failure?

A

elevated TSH

56
Q

Grave’s Disease

A
  • a type II hypersensitivity with IgG against TSH receptors
  • presents with enlarged thyroid, lid lag and exophthalmos, pretibial myxedema, tachycardia and palpitations, warm and flushed skin, fine tremors, difficulty concentrating, and delayed menarche in girls or gynecomastia in boys
  • thyroid storm is a potential fatal complication
  • histology reveals a hypertrophic, hyper plastic thyroid with irregular follicles and scalloped colloid
  • labs find elevated total and free T3/T4, low TSH, hypocholesterolemia, and increased serum glucose
  • treatment involves B-blockers and methiomazole/PTU, subtotal thyroidectomy, and radioactive iodine ablation
57
Q

What is the advantage of PTU over methiomazole?

A

PTU also blocks peripheral conversion of T4 to T3

58
Q

What are the primary effects of T3?

A
  • brain maturation
  • bone growth
  • beta-adrenergic effects (increase CO, HR, SV, contractility)
  • basal metabolic rate increase (via increase in Na/K-ATPase activity which increases O2 consumption, RR, and body temperature)
59
Q

What is 1a-hydroxylase?

A

an enzyme found in the PCT, which converts inactive vitamin D to the active dihydroxy form

60
Q

What are the primary effects of PTH?

A
  • increase bone osteoclast activity by inducing osteoblasts to release RANKL, thereby resorbing calcium and phosphate
  • increase renal calcium absorption and decrease renal phosphate rabsorption
  • trigger activation of D3, which increases absorption of calcium and phosphate from the gut
61
Q

What is the most potent form of vitamin D?

A

1,25-OH vitamin D (aka calcitriol)

62
Q

What are the actions of calcitriol?

A
  • stimulates absorption of calcium and phosphate from the intestinal lumen
  • promotes absorption of calcium and phosphate form the renal tubules
  • stimulates bone resorption
63
Q

Hypocalcemia

A
  • defined as a serum calcium less than 8 or ionized calcium less than 2.5
  • presents with tetany (including carpopedal spasms of teh wrists and ankles and laryngospasm), paresthesias, and seizures
  • in the early neonatal period (younger than 4 days), this may be due to prematurity, IUGR, asphyxia, IDM, or hypomagnesemia
  • in the late neonatal period (older than 4 days), it may be due to hypoparathyroidism, DiGeorge syndrome, or hyperphosphatemia
  • in childhood, it’s most often due to hypoparathyroidism, pseudohypoparathyroidism, hypomagnesemia, or vitamin D deficiency
  • patients should undergo evaluation via serum calcium, phosphorus, and magnesium; ECG; PTH level; vitamin D level, and radiographs of the wrists and knees
  • correct calcium with oral therapy if there are no seizures or only moderate tetany; use IV calcium gluconate if patients are more symptomatic; add calcitriol for patients with chronic hypoparathyroidism
64
Q

What is pseudohypocalcemia?

A

a factitious lowering of total calcium levels that results from low serum albumin levels; the ionized calcium level will be normal

65
Q

Neonatal Hypoparathyroidism

A
  • a transient hypocalcemia hypoparathyroidism seen in the first four days of life
  • usually caused by asymptomatic maternal hyperparathyroidism in the mother, which allows high serum calcium to cross the placenta and suppress fetal PTH release
  • patients have low calcium and elevated phosphorous
66
Q

Pseudohypoparathyroidism

A
  • a hypoparathyroidism due to end-organ resistance to PTH
  • labs will reveal hypocalcemia in the setting of elevated PTH
  • most commonly due to an autosomal dominant Gs mutation
  • associated with developmental delay, short stature, and short 4th and 5th digits
67
Q

How do magnesium levels affect calcium metabolism?

A

low magnetism may cause hypocalcemia because it interferes with the release of PTH

68
Q

Rickets

A
  • vitamin D deficiency in children, with resulting hypophosphatemia and hypocalcemia, which leads to defective mineralization of osteoid
  • deficiency is most often due to decreased sun exposure, poor diet, malabsorption, liver failure, or renal failure
  • typically seen in children under the age of 1
  • presents with pigeon-breast deformity (anterior protrusion of the sternum), frontal bossing, rachitic rosary, and bowing of the legs in ambulating children
  • labs reveal hypocalcemia, hypophosphatemia, secondary hyperparathyroidism, and elevated alkaline phosphatase
  • x-rays demonstrate “looser zones” also known as pseudofractures, epiphyseal widening, and metaphysical cupping/fraying
69
Q

Vitamin D-Dependent Rickets

A
  • an autosomal recessive condition due to a 1a-hydroxylase deficiency in the kidneys
  • patients present with increased PTH, low vitamin D levels, low calcium, low phosphorus, and increased alkaline phosphatase
70
Q

Vitamin D-Resistant Rickets

A
  • an X-linked dominant disorder, which causes renal tubular phosphorus to leak, resulting in a low serum phosphorus level
  • the most common form of rickets in the US
  • patients present with rickets but normal calcium and low phosphorus
  • treated with phosphate supplements and 1,25-OH Vitamin D analogs
71
Q

Central Diabetes Insipidous

A
  • a disease caused by low levels of ADH production
  • the result is frequent urination of dilute urine and the inability to concentrate urine even during periods of water restriction
  • presents with nocturne, enuresis, poor weight gain, polydipsia, and polyuria as well as a hypernatremic dehydration and increased serum osmolality
  • treat with desmopressin, an ADH analog
72
Q

Nephrogenic Diabetes Insipidous

A
  • a disease most frequently caused by an X-linked recessive mutation in the V2 receptor for ADH
  • the result is frequent urination of dilute urine and the inability to concentrate urine even during periods of water restriction
  • presents with nocturne, enuresis, poor weight gain, polydipsia, and polyuria as well as a hypernatremic dehydration and increased serum osmolality
  • ADH levels are high and desmopressin is not an effective treatment
73
Q

What are the typical symptoms of hypoglycemia?

A
  • newborns or infants experience lethargy, myoclonic jerks, cyanosis, apnea, or seizures
  • older children experience tachycardia, diaphoresis, tremors, headaches, or seizures
74
Q

Transient Neonatal Hypoglycemia

A
  • serum glucose less than 40 or whole blood glucose less than 45
  • can be due to inadequate substrate as in prematurity, fetal distress, SGA, or LGA or to inappropriate hyperinsulinism as in SGA infants and infants of diabetic mothers
  • presents with lethargy, myoclonic jerks, cyanosis, apnea, or seizures
75
Q

Persistent Neonatal Hypoglycemia

A
  • serum glucose less than 40 or whole blood glucose less than 45 which persists for longer than 3 days
  • can be due to hyperinsulinsm secondary to islet cell hyperplasia or Beckwith-Wiedemann syndrome, hereditary defects in carbohydrate or amino acid metabolism, or hormone deficiencies like GH or cortisol
  • presents with lethargy, myoclonic jerks, cyanosis, apnea, or seizures
76
Q

What is the most likely diagnosis in a neonate with hypoglycemia, microphallus, and cleft palate?

A

these are all suggestive of congenital hypopituitarism leading to hormone deficiencies

77
Q

List four possible causes of hypoglycemia in childhood.

A
  • ketotic hypoglycemia
  • ingestions (particularly alcohol or oral hypoglycemic agents)
  • inborn errors of metabolism
  • hyperinsulinism
78
Q

Ketotic Hypoglycemia

A
  • defined as hypoglycemia occurring late in the morning in the presence of ketonuria and a low insulin level
  • it represents an inability to adapt to a fasting state
  • the most common cause of hypoglycemia in children 1-6 years old
  • children typically present as thin individuals and become hypoglycemia after intercurrent infection
79
Q

Why does alcohol ingestion lead to hypoglycemia?

A

it depletes essential cofactors required for gluconeogenesis

Pediatrics BRS (20 decks)

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