Endo Flashcards
What is the the mode of inheritance of PAIS?
Chromosomes: FiSH SRY+ 46 XY ***LH/testosterone responsive to HCG stim test*** X-linked recessive - 50% of XY children born to maternal carriers are symptomatic - aunt with ¡pAst i/YAgay be xr with
How does calcium increase in newborn postnatally?
Increase in PTH
What are classic causes of neonatal hypocalcemia?
Gestational diabetes and preeclampsia
Mothers have PTH dysfunction that doesn’t affect mothers but does affect babies
What is cutoff of TSH that will make you more likely to treat based in NBS?
Tsh>40
Send confirmatory testing and treat right away
Confirmatory tsh>20 after 24hrs and >10 after 7 days suggestive of hypothyroidism
Maternal thyroid hormone is critical in which trimester?
First trimester development
Which is most common cause of congenital hypothyroidism?
Dysgenesis 85%
Ectopic thyroid is most common
Most sensitive and specific test of hypothyroidism ?
TSH
Dopamine infusion can lead to transient _______ in TSH
Decrease
Good measure of thyroid function?
Free T4
Only free form can enter the cell
What is Pendred Syndrome?
What is the association with hypothyroidism?
Deafness (CN 8)
Goiter
Hypothyroidism
AR
Cause of permament primary hypothyroidism
Iodide organification defect
What does T3 resin uptake measure?
Amount of unsaturated binding sites on TBG
Resin uptake is inversely proportional to the number of binding sites on TBG
Management of neonatal DI
Thiazide diuretics are preferred over DDAVP as the dosing for DDaVP is difficult in neonates and can lead to swings from hyper to hyponatremia
Thiazides work by decreasing distal tubular reabsorption of sodium via inhibition of sodium-chloride cotransported resulting in natriuresis and volume contraction which results in increased water and Na reabsorption in distal tubule and collecting duct.
Adding free water to formula may lead to FTT and not recommended
Which thyroid hormone transfers freely across the placenta?
Thyroyropin releasing hormone
Also TSH receptor stimulating and blocking antibodies
T3 and T4 are partially permeable
Most common cause of virilization of genetic female neonate is?
CAH
The optimal postnatal age to determine baseline thyroid function in newborn?
24 hrs
How does hydrocort help with BP?
Inhibits catecholamine metabolism, blocking reuptake of circulating catecholamines-> increasing BP
2dary effect: upregulates cardiovascular adrenergic receptors
Where is calcium stored in the body?
When and how is is transferred during pregnancy?
Skeletal system contains
99% of whole body calcium
85% phosphorus
65% magnesium
3rd Trimester - 80% of Ca+ and phosphorus are transferred by active transport across the placenta (*regardless of maternal status)
From 24 weeks onwards the accretion rates are
Ca 120mg/kg/d
Phos 60mg/kg/d
Aside from glucose and insulin, what compound(s) contribute to the development of macrosomia in IDM babies?
Insulin like growth factor 1
Insulin like growth factor binding protein 3
Whst is the gold standard for assessing bone mineralization and fragility?
Dual energy x ray absorptiometry
DEXA scan
Term neonate
hyponatremic hypokalemic crisis
Normal glucocorticoid and androgen secretion
What is most likely gene mutation causing this enzyme defect ?
CYP21
Mutation of 21 hydroxylase gene CYP21 is MCC of CAH in North America
How do you treat a symptomatic baby with congenital hyperthyroidism from maternal Graves’ disease
“PTU (propylthiouracil) or carbimazole (methimazole) to inhibit organification and block peripheral conversion of T4 to more active T3
- Both will be detected in breastmilk
Beta-blocker (propranolol) to control tachycardia and inhibit peripheral conversion from T4 to T3”
When does the fetal thyroid gland begin secreting thyroid hormone?
12 weeks
In the 1st trimester, testosterone production from the Leydig cells is driven by _______
Placental human chorionic gonadotropin (HCG)
_________ increases in the 2nd trimester and stimulates phallic enlargement and trsticukar descent.
Fetal pituitary luteinizing hormone
Thyroid gland develops from
Median endodermal thickening in primitive pharyngeal floor at 5-7 weeks gestation
WHat GA does TRH production, thyroglobulin, TSH and thyroid hormone start?
TRH from hypothalamus ar 6-8 weeks
Thyroglobulin ~8 weeks
Iodide starts accumulating at 10 weeks
TSH by pituitary gland and thyroid hormones~12 weeks
What medication can cause transient decrease in TSH?
Dopamine
What is the preferred drug for treating maternal hyperthyroidism?
PTU
Assoc’d with face and neck cysts
T or F
Methimazole is a first line agent in the first trimester for treatment of maternal hyperthyroidism
False
Disrupts organogenesis
- choanal atresia, EA, cutis aplasia,
abdominal wall defects, VSD
Use AFTER 1st trimester
Which hyper insulinism
patients are responsive to diazoxide?
Which pts do not respond?
Respond
- Hyper insulinism hyper ammonemia syndrome
- deficiency in short chain L3 hydroxyacyl coenzyme a dehydrogenase
No response
- inactivating mutations in ABCC8 or KCNJ11 gene
Diazoxide is a K ATP channel agonist
In comparison to term neonate, preterm neonates gave higher serum concentrations of which thyroid enzyme/hormone?
Thyroglobulin (likely due to decrease degradation or clearance)
Premies have lower TBG and therefore T4
How does stressful deliveries and RDS affect cortisol levels in preemies?
Increases cortisol levels
T or F Erythropoietin levels (fetal and AF) are markers of intrauterine chronic hypoxia
True
Chronic fetal hypoxia is seen with IDDM pregnancies
Fetus adapts to chronic hypoxia by increasing its oxygen carrying capacity (with erythropoietin synthesis)
Drugs that affect thyroid function (T4)
Increased T4 - Aminophylline
Variable reductions T4- sepsis, IVH, dopamine, MSO4
Compare to preemie formulas, human milk contains what fraction of calcium and phosphorus?
1/5 👀
When would benefit from phosphorus supplementation in metabolic bone disease?
High TRP levels
Low to normal PTH
hypophosphatemia
How to calculate TRP levels?
Tubular Réabsorption of Phosphorus
TRP = 1- [(urine phos x serum Cr) / (serum phos x urine Cr)] x100
Which enzyme is involved in glucose regulated insulin secretion?
Glucokinase - glucose phosphorylation
Which maternal drug may lead to a false positive nbn screen for hypothyroidism ?
(Excess iodine)
Amiodarone
Pendred syndrome
AR organification defect with congenital eight nerve abnormality leading to deafness, goiter during childhood
Dx Positive percholate discharge test with rapid loss of radioactive iodine from thyroid gland
Maternal diabetes is associated with which type of cardiac anomaly?
Hypertrophic cardiomyopathy, VSD, TGA
Renal anomalies, caudal regression , NTD, small left colon
Most common cause of congenital hypothyroidism
Thyroid dysgenesis (75%)
2/2 complete or partial absence of thyroid gland
