peds15 Flashcards
most common cause of congenital hypothyroidism
thyroid dysgenesis; absent or hypoplasia; or ectopic thyroid gland anywhere from tongue to mid-chest
thyroid dyshormonegenesis
inborn errors of thyroid synthesis; cause of congenital hypothyroidism; usually presents with goiter
pendred syndrome
most common thyroid dyshormonegenesis and is associatied with sensorineural hearing loss
clinical features of hypothyroidism
history of prolonged jaundice and poor feeding; lethargy and constipation; large ant and post fontanelles; protruding tongue, umbilical hernia, etc.
management of hypothyroidism
L-thyroxine; must start ASAP to avoid brain damage
hashimotos disease
chronic lymphocytic thyroiditis; most common cause of acquired hypothyroidism; thyroid autoantibodies;
hashitoxicosis
transient hyperthyroidism that may occur in some patients
clinical features of hyperthyroidism
lid lag and exophthalmos; thyroid is smooth and enlarged; tachycardia, palpitations; skin is warm and flushed; tremors, delayed puberty
most common cause of hyperthyroidism in children
graves disease
anti-thyroid medications
PTU and methimazole both inhibit thyroid synthesis; ptu also impairs conversion of peripheral T4 to T3;
radioactive iodine
can be used in adolescents noncompliant with antithyroid meds; its useresults in permanent hypothyroidism
what releases calcium and phosphorous from bone?
vit D and PTH
PTH
releases calcium from bone and reabsorbs calcium from kidneys; releases phophorous from bone and excretes phos from kidneys
effect of PTH on the kidney
calcium and bicarb reabsorption and phos excretion
what happens in the kidney with vit D?
1-alpha hydroxylase vit D made int eh kidney converts 25-OH-vit D (made in the liver) to the active 1,25-OH vit D
pseudohypocalcemia
low serum albumin (like in nephrotic syndrome) lead to factitious lowering of calcium; make sure you measure ionized calcium level to verify true hypocalcemia
clinical features of hypocalcemia
tetany (carpopedal spasm, laryngospasm, paresthesia), seizures
early neonatal hypocalcemia
younger than 4 days of age; usually transient; hypomagnesemia may also result on hypocalcemia
late neonatal hypocalcemia
older than 4 days of age; can be caused by hypoparathyroidism, diGeorge syndrome, or hyperphosphatemia
childhood hypocalcemia
may be caused by hypoparathyroidism, pseudohypoparathyroidism (parathyroid resistance- would have elevated PTH), hypomagnesemia, or vit D def
how does hypomagnesemia cause hypocalcemia?
interferes with PTH release
heart finding in hypocalcemia
prolonged QT interval
vit d would have what effect on calcium and what effect on phosphorous
decreased serum levels of both
how to evaluate for rickets
radiograph of wrists or knees
rickets
vit D def that results in deficient mineralizationof growing bones with a normal bone matrix
factors that predispose to rickets
exclusively breastfed infants with minimal sunshine; fad diets; use of anticonvulsant meds (phenytoin, phenobarbitoal), which interfere w liver metabolism; renal or hepatic failure
how can Gi disorders lead to rickets?
fat malabsorption results in vit D def (CF, celiac disease)
vit D-dependent rickets
autosomal recessive, rare; enzyme def in the kidneys of 1 alpha hydroxylase vit D
vit D resistant rickets
aka familial hypophosphatemia; most common form of rickets; x-linked dom; caused by renal tubular phosphorous leak, resulting in low serum phosphorous; treat with phosphate supp and vit D analog
oncogenous rickets
phosphate deficient form of rickets caused by a bone or soft tissue tumor; should be considered in patients who present with bone pain or myopathy
clinical features of rickets
usually in first two years of life and in adolescence; wrists, knees, and ribs affected; short stature; weight bearing bones are bowed; craniotabes, frontal bossing, delayed suture closure
rachitic rosary
prominent costochondral junctions seen in rickets
diabetes insip
inability to maximally concentrate the urine becase of low ADH or renal unresponsiveness to ADH
langerhans cell histiocytosis
can be a causes of DI
granulomatous disease
sarcoidosis, tuberculosis for example; can lead to central DI
nephrogenic DI
x-linked recessive disorder
management of central DI
DDAVP
symptoms of hypoglycemia in newborns
lethargy, myoclonic jerks, cyanosis, apnea, or seizures
symptoms of hypoglycemia in older children
tachycardia, diaphoresis, tremores, headaches, or seizures
Transient neonatal hypoglycemia
usually detected by screening for high-risk infants; high risk conditions include prematurity, fetal distress, SGA and LGA
persistent neonatal hypoglycemia
persists for longer than 3 days; can be caused by hyperinsulinemia, defects in carb metabolism or AA metabolism, or hormone def
causes of hyperinsulinemia in new born
islet cell hyperplasia (nesidioblastosis), beckwith-weidemann syndrome
neonate presents with hypoglycemia, microphallus, and midline defects like cleft palate
think congenital hypopituitarism
what hormone def can lead to hypoglycemia?
GH def and cortisol def
most common cause of hypoglycemia in kids 1-6 years old
ketotic hypoglycemia; occurs late morning in the presence of ketonuria and low insulin; due to inability to adapt to fasting state
ingestions of what should be considered in ddx of hypoglycemia?
alcohol, oral hypoglycemic agents
