Endocrine & Metabolic Flashcards
Beckwith-Wiedemann Syndrome
Unknown cause
Autosomal dominant inheritance
Characteristics:
• Macroglossia
• Abdominal Wall Defect
• Organomegaly
• Including pancreas – dump insulin causing
hypoglycemia & islet cell hyperplasia
• Hypoglycemia
• PolycythemiaCalcium Regulation processes:
• Maintenance of cell membrane permeability
• Activation of enzyme reactions for muscle
contraction
• Nerve transmission
• Blood Clotting
• Normal functioning & development of the skeletal
system
Calcium Regulation & the Parathyroid Hormone (PTH)
- Mobilizes calcium and phosphorous from bone
* Decreases renal excretion
Calcium Regulation & 1,25 Dihyroxycholecalcerferol Vitamin D (hormone)
• Required for PTH to work
• Increases absorption of Calcium and Phosphorous
from the gut
Calcium Regulation & Calcitonin
- Inhibits calcium mobilization from the bone
- Increases calcium excretion
- Decreases serum calcium
Factors that Influence Calcium Levels
- Acidosis increases Ca
- Alkalosis decreases Ca
- Phosphorous inhibits the absorption of Calcium
A normal magnesium level is required for ? to work
• Parathyroid hormone
Definition of Hypocalcemia
- Total Ca of < 7.0 mg/dL
* Ionized Ca < 3 - 4.4 mg/dL or < 0.75 – 1.1 mmol/L
Definition of Hypercalcemia
- Total Ca of < 11.0 mg/dL
* Ionized Ca < 5.8 mg/dL
Causes of Hypercalcemia
- Iatrogenic
- Hyperparathyroidism
- Decreases phosphate (phosphorous inhibits Ca)
- Familial Infantile Hypercalcemia
Hypercalcemia Treatment
- Hydrate
- Promote excretion with Lasix
- Decrease Ca and Vit D intake
- Increase Phosphorous intake
Causes of Hypomagnesemia
- Low maternal level
- Placental insufficiency
- Prematurity or IUGR
- Increased losses with renal or intestinal disorders
- Hypoparathyroidism
What does the Adrenal Medulla do?
• Secretes catecholamines (epinephrine &
norepinephrine)
• “Fight or Flight” response
What does the Adrenal Cortex do?
Production of:
• Glucocorticoids
• Mineralcorticoids
• Androgens
Actions of Cortisol (Glucocorticoid)
• Regulates blood sugar
• Important for growth
• Maintains cardiovascular function
• Releases in times of stress to increase glucose,
increase cardiac output, and maintain vascular tone.
Actions of Aldosterone (Mineralcorticoid)
• Regulates fluid and electrolyte balance
• Stimulates the reabsorption of sodium and water in
the distal collecting tubules.
• Inhibits the secretion of potassium
• Important in maintaining blood pressure,
intravascular volume, cardiac function, and
electrolytes
What is adrenal insufficiency?
• A transient phenomenon in the VLBW infant
• Related to the hypothalamic-pituitary-adrenal
immature (the pathway is immature)
• Levels of cortisol are decreased in the VLBW infant
• Levels do not increase during times of stress
• Cortisol suppression related to exogenous steroid
administration
Clinical Manifestations of Adrenal Insufficiency
- Glucose abnormalities
- Refractory Hypotension
- Decreased cardiac output, acidosis, and shock
- Decreased urinary output
- Infection
- Hyponatremia, Hyperkalemia
- Tachycardia
What is the treatment for Adrenal insufficiency?
- Hydrocortisone therapy???
- How much????
• Recover on own by 14 days of life
Thyroid excretes 2 hormones
- Thyroxine (T4)
- Much of T4 is converted to T3
• Triiodothyronine (T3)
• 99% are bound to protein (not able to produce
effects)
• 1% is free (able to produce effects)
What does the pituitary secrete that stimulates the thyroid to release its hormones?
• Thyroid Stimulating Hormone (TSH)
Congenital Hypothyroidism: Causes
• Dysgenic or absent thyroid gland
• Deficient synthesis of thyroid hormones
• Maldevelopment or absence of the anterior
pituitary
Congenital Hypothyroidism: Clinical Manifestations
• Often asymptomatic
• Symptoms are often subtle and nonspecific
• May be associated with chromosomal defects (.
Downs)
• Post dates / LGA
• Defective skeletal maturation & growth
• Hypotonia
• Large tongue
• Umbilical hernia
• Temperature instability
• Poor feedingCongenital Hypothyroidism: Diagnosis
• State metabolic screen
- T4 is low
- TSH is elevated
• Anterior pituitary sees the low T4 and cranks out
the
• TSH to stimulate the thyroid
Congenital Hypothyroidism: Treatment
- L-thyroxine (a synthetic T4)
- Monitor levels
- Irreversible mental retardation if not treated
Hypothyroxinemia of Prematurity
What is it?
- A transient phenomena due to immaturity
- Fetal thyroid hormones not made until 30 weeks
- Severity is dependent on gestational age
- Persists for 4-6 weeks
- No proven benefit with treatment.
- Low T4
- Normal TSH
Hyperthyroidism
Neonatal Thyrotoxicosis
• Thyroid gland secretes excessive thyroid hormone
• 90% are due to Maternal Graves disease
• Transplacental transfer of thyroid stimulating
immunoglobulins (Mom has thyroid stimulating
immunoglobulins that cross the placenta and
stimulate the babies thyroid)
• May be transient or prolonged
• Considered a medical emergency
Hyperthyroidism: Clinical Manifestations
- IUGR
- Irritability
- Tachycardia & tachypnea
- Cardiac failure
- Hyperthermia
- Vomiting & diarrhea (due to overeating)
- Failure to thrive
- Goiter
What is the best position to exam the neonatal thyroid?
• Sitting up
Hyperthyroidism: Diagnosis
• High T4
• Because the maternal immunoglobulins are
stimulate the infants thyroid
• Low TSH
• Because the anterior pituitary sees the high T4 level
and is trying not to stimulate the thyroid anymore.
Hyperthyroidism: Treatment
Acute treatment:
• PTU (Prophlthiouracil) – blocks the thyroid from
making hormones
Chronic treatment:
• Lugol’s solution – iodine solution
Osteopenia of Prematurity: What is it?
- Thinning and undermineralization of the bone
- Occurs in 50% of infants < 1000 grams
- Peaks in 2-3 months of age
Osteopenia of Prematurity and Prematurity
• 80% of bone mineralization occurs during 3rd
trimester
• Intrauterine mineral accretion is much greater than
extrauterine
• Inadequate postnatal bone mineralization
Osteopenia of Prematurity: Causes
• Inadequate calcium, phosphorus, & Vit D intake
• Feeding intolerance
• Lasix
• Increases renal calcium loss
• Stimulates calcium reabsorption from bone
• Aminophylline – calcium excretion in urine
• Phenobarbital & Dilantin – enhanced Vit D
metabolism
What do you need to make bones?
Vitamin D
o 1,25 dihyroxyvitamin D
o Stimulates absorption of calcium & phosphorous
from the intestines
Phosphorous
o Stimulates bone formation
o Inhibits reabsorption of bone
CalciumClinical Manifestations of Osteopenia of Prematurity
- Normal calcium levels
- Normal to low phosphorous (< 3.5 mg/dL)
- Increased alkaline phosphate (> 499)
- Enzyme released due to bone breakdown
- Cupping & fraying of the metaphysic
- Decreased bone density
- Fractures of the long bones & ribs
Osteopenia of Prematurity: Treatment
- Prevention!
- Adequate amounts of calcium & phosphorous
- Adequate kcal & protein
- 400 IU of vitamin D
- Fortify breastmilk / use of premature formulas
Osteopenia of Prematurity: Prognosis
- Self-resolving
* Increased incidence of BPD
When are the gonads formed?
6 – 7 weeks gestation
When is testosterone first released?
6 – 7 weeks gestation
When is sexual differentiation?
8 – 9 weeks gestation
Klinefelter’s Syndrome
- 47xxy
- hypogonadism
- dysgenesis of the seminiferous tubules
- Not generally diagnosed in the neonatal period
Hermaphrodite
- 46xx or 46xy mosaic
* Both ovaries and testes in one individual
What is an inborn error in metabolism?
• Autosomal recessive genetic defect
• Due to the absence of an enzyme, cofactor, or
transport
• protein which either degrades or converts one
substance into another.
• This absence results in either a toxic accumulation
of the substrate or the deficiency itself can be toxic
Inborn Error of Metabolism (Pathway)
• The lack of the enzyme leads to an excess (elevation) of the precursor and a deficiency (decrease) in the substrate.
