Endocrinology Flashcards
What regulates prolactin release?
Prolactin is under tonic hypothalamic inhibition by dopamine sent down the pituitary stalk Prolactin increases during sleep and with stress, lactation, and stimulation of the nipple. Antidopaminergic drugs (such as metoclopramide and phenothiazines) also increase prolactin, as does TRH; thus, prolactin elevates with primary hypothyroidism and with any inhibition in the production of dopamine from the hypothalamus (most commonly,medications).
True or false? Prolactin levels are high in hypothyroidism.
True
TRH increased prolactin
What is septooptic dysplasia?
a.k.a. de Morsier syndrome
Includes:
- Abnormality of the optic nerve (absence of the optic chiasm, optic nerve hypoplasia, orboth);
- Agenesis or hypoplasia of the septum pellucidum or corpus callosum, or both; and
- Often variable degrees of hypothalamic insufficiency
Which endocrine abnormality do you look for if a patient has a solitary maxillary incisor?
GH deficiency
Which structure is key in determining the level of pituitary involvement in a patient with an ectopic posterior pituitary?
Pituitary stalk
Patients who have an ectopic pituitary and a normal stalk have isolated growth hormone deficiency.
Patients with an ectopic pituitary and an abnormal stalk tend to have multiple pituitary hormonedeficiencies.
What is the most common tumor to cause pituitary hormone deficiency?
Craniopharyngioma
What are the clinical clues that make you suspect congenital GH deficiency?
Microphallus
Hypoglycaemia
Direct hyperbilirubinaemia
What are the classic signs and symptoms of congenital GH deficiency?
Falling height Characteristic facies develops over time - Round head and short, broad face - Frontal bone is prominent - Depressed, saddle-shaped, nose - Eyes appear to be bulging - High-pitched voice Gonads are small Facial, axillary, and pubic hair is usually sparse Intelligence is typicallynormal
What is idiopathic short stature?
Shorter
Grow at slower rate
GH levels normal
True or false? Children with constitutional growth delay typically require GH to reach their normal adult height.
FALSE
What is Russell-Silver syndrome?
Russell-Silver syndrome causes:
- Short stature
- Frontal bossing
- Triangular facies
- Shortened and incurved 5th fingers (clinodactyly)
- Asymmetry.
- SGA
- FTT
Which children with short stature are FDA approved to receive GH to help them reach a more normal height?
Idiopathic Short Stature
ie. Children who are not GH deficient but whose heights are very short (>2.25 SD below the mean), who are unlikely to reach normal heights (remaining at >2 SD below the mean), and who do not have a condition that is better treated by other means.
A child with a severe head injury 3 days ago now has severe hyponatremia; what is 1 etiology you should consider?
Neurogenic (central) Diabetes Insipidus
What is the most common medication to cause nephrogenic DI?
Lithium
How is SIADH best managed?
Fluid restrict
Tx underlying cause
Name 3 abnormal causes of tall stature?
Klinfelter
Marfans
Homocystinuria
What is Sotos syndrome?
Syndrome with rapid growth early in childhood but no evidence of an endocrine disorder.
Rare
NSD1 genes
Born above the 90th percentile and then grow rapidly in the 1st year of life to >97th percentile.
Slows around 4-5yo
Big hands, feet and head
Long narrow face, big forehead, pointed chin
How might an adolescent female present with prolactinoma?
Headache, amenorrhea, and galactorrhea
What is the best way to diagnose a prolactinoma?
MRI of sella
Which hormone is responsible for the initiation of puberty?
GnRH
After the initial sign of puberty, how long is it before menarche begins in most girls?
2-2.5 years
THELARCHE -> ADRENARCHE -> MAXIMUM GROWTH VELOCITY -> MENARCHE
When does peak height velocity occur in girls?
At breast stage 2-3, between 11 to 12yo
What is the mean menarche age?
12.5 years
What are the 1st signs of puberty in boys?
testicular enlargement > 4mL & thinning of scrotum
Which occurs first, penis lengthening or growth of pubic hair?
penis lengthening
When does the growth spurt occur in mostboys?
2 years later than for girls, at genital stage 4 or 5
eg. 13-14yo
Which lab result indicates central precocious puberty?
LH spikes
What is the most common brain lesion to cause central precocious puberty?
Hypothalamic hamartoma
What causes peripheral precocious puberty?
Excess secretion of sex hormones from the gonads, adrenal glands, or germ cell tumors and from exogenous exposure to sexsteroids
What is McCune-Albright syndrome?
Endocrine disorder
Precocious puberty
- vaginal bleeding, breast enlargement
Patchy pigmentation (i.e., café-au-lait macules with irregular “coast of Maine” borders)
Fibrous dysplasia
Due to a missense mutation in the gene that encodes for the protein that triggers cyclic adenosine monophosphate (cAMP) formation
What is the classic presentation for McCune-Albright syndrome?
Vaginal bleeding
What is premature thelarche?
Isolated breast development
Does premature thelarche in a 6-month-old child require any special therapy?
No usually benign, but is diagnosis of exclusion.
Need to ensure no other sources of exogenous estrogen
What is premature adrenarche?
Benign condition caused by early production of adrenal androgens
What causes pubertal gynecomastia?
Benign
Self-limited
Increase in breast tissue speculated to result from a temporary alteration in the estrogen:testosterone ratio in pubertal boys.
What are the 2 most important TFTs?
TSH and Free T4
What clinical states result in a high T4 measurement due to a high TBG?
clinically irrelevant
Estrogen: supplements, oral contraceptives, and pregnancy Tamoxifen, clofibrate, narcotics, hepatitis, biliary cirrhosis
What clinical states result in a low T4 measurement due to a decrease in TBG?
Androgens
Glucocorticoids
Nephrotic syndrome
Inherited TBG deficiency
Radioiodine uptake (RAIU) is high in which disorders?
Gravesdisease Hot nodules (e.g., multinodular goiter, toxic solitary nodule, hCG-secretingtumor)
What is the most common cause of congenital hypothyroidism?
Thyroid dysgenesis
Are most infants with congenital hypothyroidism asymptomatic at birth?
YES
d.t transplacental passage of FT4
What is the best time frame to screen infants for congenital hypothyroidism?
Neonatal! NBS
- need to start Tx before 2 weeks to prevent ID and developmental delay
How are most infants with congenital hypothyroidism identified?
NBS - High TSH and low FT4
What fontanelle finding is helpful in diagnosing congenital hypothyroidism?
Enlarged posterior fontanelle
What bone finding in the femur helps with the diagnosis of congenital hypothyroidism?
absent distal femoral epiphysis
What happens to growth in a child with acquired hypothyroidism?
Growth failure
What is another name for Hashimoto disease?
Chronic autoimmune thyroiditis (a.k.a. chronic lymphocytic thyroiditis)
What is the most common cause of goiter in children >6 years of age in the U.S.?
Chronic autoimmune thyroiditis
What is the recommended follow-up and management for a patient with euthyroid Hashimoto disease?
TFTs every 6 months
What is the most likely cause of elevated TSH in a patient on levothyroxine?
NONcompliance
How do you treat a patient with euthyroid sick syndrome?
Direct treatment at the primary illness. No replacement of T3 or T4 isnecessary.
What usually precipitates subacute thyroiditis?
URTI
How does subacute thyroiditis present?
Fever
Thyroid gland pain and tenderness
What is the therapy for subacute thyroiditis?
Analgesics
Prednisolone in severe cases
What is the most common cause of thyrotoxicosis in children and adolescents?
Graves disease
How does Graves’ present in childhood?
Muscle weakness Increasing anxiety Palpitations Increased appetite Weight loss, but some have weight increase Behavior problems
Cardiac signs/symptoms by the time of diagnosis, with cardiomegaly, tachycardia, widened pulse pressure (or frank hypertension), and gallop rhythms
What is the treatment for Graves disease?
Stop toxic effects = Beta Blockers
Treat =
Ablation of the thyroid with radioactiveiodine
Surgicalthyroidectomy
Blocking thyroid hormone biosynthesis withdrugs
What are 2 possible complications from thyroidectomy for Graves disease?
Post-op hypoparathyroidism and
Recurrent laryngeal nerve damage
What is the most common side effect from PTU and methimazole? What is the most serious side effect?
skin rash = most common
Granyulocytopenia = most serious
& Hepatotoxicity and death
What correlates with the risk of neonatal Graves’ in a baby born to a mother with Graves disease?
Maternal level of TSI
What factors concern you about a solitary thyroid nodule in a child?
Thyroid cancer
What hormone does medullary carcinoma of the thyroid produce?
Produces calcitonin
What is the most definitive test that can be performed on a patient’s thyroid nodule?
FNA
A patient with hypercalcemia and hypophosphatemia has which disorder?
Hyperparathyroidism
Which condition causes hypocalcemia with hyperphosphatemia?
Hypoparathyroidism
Which electrolyte abnormality is common with DiGeorge syndrome?
Neonatal Hypocalcaemia
Which ECG finding is seen in severe hypocalcemia?
Prolongation QTC
-> Risk of Torsades
How is rickets diagnosed?
Lab:
- elevated ALP
- High PTH, Low Calcium and Low Phosphorous
Xray:
- changes at growth plates
What are secondary causes of hyperparathyroidism in children?
Vitamin D–deficient rickets
Malabsorption syndromes
Pseudohypoparathyroidism
Chronic renaldisease
What is the difference between MEN2A and 2B?
MEN2A
- Hyperparathyroidism
- Medullary thyroid cancer
- Pheochromocytoma
MEN2B
- Does NOT have Hyperparathyroidism
- Medullary thyroid cancer
- Pheochromocytoma
- Mucosal neuromas
- Marfinoid body habitus
How does hyperparathyroidism present in children?
Manifestations from their hypercalcemia - Muscular weakness - N/V - Constipation - Fever They can also present with bed-wetting and polyuria.
Which laboratory finding helps you differentiate primary from secondary hyperparathyroidism?
Primary hyperparathyroidism = low phosphorus, high calcium, elevated PTH
Secondary = Hypercalcemia with SUPPRESSED PTH
What causes hypercalcemia in patients with sarcoidosis?
1,25 OH D2 high stimulates Ca
Increased pigmentation is seen in what type of adrenal deficiency?
Primary adrenal insufficiency
What are the most common causes of ACTH deficiency?
Stopping or missing exogenous steroids that have been used chronically
Name 3 inborn defects of steroidogenesis that almost always have salt-wasting characteristics.
21-hydroxylasedeficiency
3β-hydroxysteroid dehydrogenasedeficiency
Lipoid CAH
What is the most common cause of Addison disease?
Autoimmune
True or false? Salt wasting is seen in familial glucocorticoid deficiency.
No
as there is normal mineralocorticoid production
What are the common presenting symptoms of congenital adrenal hypoplasia?
Increased pigmentation
Symptoms related to salt wasting
Symptoms due to low levels of adrenal steroids
Cryptorchidism
What are the risk factors for adrenal crisis?
Stressors, such as illness or surgery
Trauma
Abrupt cessation of steroid treatment
Drugs (e.g., morphine, laxatives, insulin, thyroid hormone