ENDOCRINOLOGY Flashcards
What are the clinical features of McCune-Albright Syndrome?
BONES AND ENDOCRINE:
- Polyostic fibrous dysplasia
- Cafe au lait spots (jagged edge “Coast of Maine” appearance)
- Hyperthyroidism
- Precocious puberty
What are the 3 Es of Diencephalic syndrome?
- Emesis
- Emaciation
- Euphoria
Results from hypothalamic tumor
Body is in catabolic state
Child will want to eat a lot
What hormones influence growth? (6)
- Growth hormone
- Insulin
- Insulin Growth Factor -1
- Cortisol
- TSH
- Androgens/estrogen
Which hormone controls prenatal growth? Postnatal growth?
Pre-natal growth: insulin
Postnatal growth: GH
What is the most accurate way of predicting adult height? What is the least accurate way?
Most accurate - bone age
Least accurate - mid parental height
3 causes of delayed bone age:
- Constitutional delay
- Chronic disease
- Endocrine disease
What is the most common cause of endocrine-related growth failure?
Primary hypothyroidism (causes growth arrest)
What is the most common cause of hypoglycemia in patients over 18 months old?
Ketotic hypoglycemia: substrate (glucose) deficiency
What is the management of a newborn found to have increased TSH and decreased thyroid hormone (T4) on newborn screening and confirmed again on bloodwork?
IMMEDIATE initiation of thyroid hormone replacement (levothyroxine)
-delay in therapy greater than 2 weeks of age can result in cognitive impairment
What are the Tanner/sexual maturity rating stages in girls?
- pubic hair
- breasts
SMR stages:
- Preadolescent
- Sparse pubic hair, small mound of breast and papilla
- Darker, increased pubic hair; enlarged breast and areola
- Coarse, abundant pubic hair; areola and papilla form double mound
- Adult feminine triangle, spread to medial surface of thighs; mature breasts, nipple projects
At what Tanner/SMR stage does menstruation occur?
30% in stage 3, 90% by stage 4
At what Tanner/SMR stage does axillary hair production occur for:
- boys
- girls
Boys: stage 4
Girls: stage 3
**Remember that girls mature more quickly than boys!
What are the Tanner/sexual maturity rating stages in boys?
- pubic hair
- penis
- testes
- No pubic hair, preadolescent penis and testes
- Sparse pubic hair; minimal change in penis size, enlarged scrotum
- Darker pubic hair, lengthening of penis, testes grow larger
- Coarse, abundant pubic hair; glans and breadth of penis increase, increased size and darkening of scrotum
- Adult distribution of pubic hair with spread to medial surface of thighs, adult size penis and testes
What is the cycle of menses?
- follicular phase
- luteal phase
- Follicular phase: begins with onset of menses –> results in mid cycle LH surge which induces ovulation from the follicle. Empty follicle then forms the corpus luteum initiating the luteal phase
- Luteal phase: progesterone and estradiol are secreted from the corpus luteum maintaining the endometrial layer of the uterus. If pregnancy does not occur and there is no HCG to maintain the corpus luteum, it dies which results in withdrawal of progesterone and thus endometrium sloughs, giving you a period
What are the stages of puberty in females?
-what age does puberty start?
Onset of puberty: 8-13 yo
- Thelarche: onset of breast development (precedes pubarche by 6-12 mo)
- Adrenarche –> Pubarche: onset of adrenal androgen production which leads to onset of sexual hair growth
- Menarche: follows thelarche by 2-3 years
Remember boobs, pubes, grow, flow
**Growth spurt starts with early puberty and occurs over 2-3 years with peak height velocity achieved about 1 year before menarche
Growth spurt is completed by what age in females?
99% of growth is complete by 15 yo
What are the stages of puberty in males?
-what age does puberty start?
Avg age of onset: 9-14 yo
- Testicular enlargement: 1 yr before pubarche
- Adrenarche/pubarche: from adrenocortical androgen production and gonadal activity
- Pubertal growth spurt: occurs 2 years later in boys than girls and occurs during SMR pubic hair stages 3 and 4
- Facial hair/voice change during SMR stage 4
Growth spurt is completed by what age in males?
99% of growth is complete by 17 yo
What does the adrenal medulla secrete?
What does the adrenal cortex secrete?
- glomerulosa
- fasciculata
- reticularis
Adrenal medulla:
-catecholamines
Adrenal cortex:
- zona glomerulosa: mineralocorticoids aka aldosterone (think glomerulus in kidney)
- zona fasciculata: glucocorticoids
- zona reticularis: sex hormones + small amt glucocorticoids (“I had sex with reticularis”)
After the onset of menarche, how much more will girls typically grow?
7 cm after menarche
-but need to get bone age xray to know for sure
What are the effects of cortisol?
- metabolic
- CVS
- growth
- immune
- skin/bone/calcium
- CNS
- Metabolic: increases serum glucose by increasing hepatic gluconeogenesis and glycolysis
- CVS: positive inotropic effect on the heart
- Growth: inhibit linear growth and skeletal maturation by decreasing GH and IGF1
- Immune: decreases inflammation and immune response
- Skin/bone/calcium: inhibits fibroblasts leading to poor wound healing, decreases serum Ca and decreases osteoblastic activity –> osteoporosis
- CNS: crosses BBB and has direct effects on brain metabolism –> stimulates appetite, insomnia, irritability, emotional lability
What are the 3 urine catecholamines you test for in cases of possible adrenal medulla tumors?
- VMA
- Metanephrine
- Normetanephrine
What are the steps of sex differentiation in utero?
- If there is a Y chromosome, then the bipotential gonads can differentiate into testes between 6-8 wks.
- The testes produce testosterone (Leydig cells) and anti-Mullerian hormone (Sertoli cells) –> testerone directs formation of the internal male reproductive organs from Wolffian ducts and AMH suppresses development of the Mullerian ducts (ie. preventing female internal reproductive organ formation)
- At 8-12 wks, the testosterone made by testes is changed to DHT (by 5 alpha reductase). DHT causes formation of male external genitalia. If there is no DHT, then female external genitalia develops.
**In infants with CAH, there is an excess of DHT due to build up of intermediate metabolites and thus female babies can have virilization (formation of male external genitalia) while still having normal female internal reproductive organs
What is the most common cause of congenital adrenal hyperplasia?
21-hydroxylase deficiency (90% of cases)
-two types: classic (severe form, 75% have salt wasting) and non-classic (milder)
In non-classic CAH, what are most common presenting features (2)?
Androgen excess manifests later in life as:
- Premature adrenarche
- Advanced bone age
- *genital ambiguity is not present at birth
- no salt-wasting (mineralocorticoid deficiency)
What is the differential diagnosis for short stature with:
- normal growth velocity (aka following growth curve) (3)
- abnormal growth velocity (aka droppping off growth curve)? (5)
Normal growth velocity:
- Constitutional growth delay (bone age < chronological age)
- Familial short stature (bone age = chronological age)
- Idiopathic short stature (height < 2 SD of mean for age with no other medical abnormalities found on investigations)
Abnormal growth velocity
- Chronic disease
- Malnutrition
- Endocrinopathies (hypothyroidism, GH deficiency, excess glucocorticoid)
- Psychosocial
- Drugs (glucocorticoids)
What is the classic triad of septo-optic dysplasia?
-diagnostic criteria?
Triad:
- Optic nerve hypoplasia (manifests as nystagmus)
- Pituitary hormone abnormalities: growth failure, hypothyroidism, adrenal insufficiency, diabetes insipidus (varying degrees)
- Midline brain defects: agenesis of septum pellucidum and/or corpus callosum
- need 2/3 of features for diagnosis (this is up for debate)
What are the two common presenting symptoms of septo-optic dysplasia in neonates?
- Hypoglycemia
2. Seizures secondary to underlying structural brain abnormalities
What investigations should be ordered in a suspected case of septo-optic dysplasia?
- Brain MRI to rule out midline brain abnormalities
- Ophtho consult
- Pituitary function: TSH, cortisol (random in a neonate is fine), growth hormone, IGF-1
* **when child is older, consider LH and FSH levels to monitor for delayed puberty
What is the normal growth velocity for children:
- < 1 yo
- 1-2 yo
- 2-3 yo
- childhood
- adolescence
- < 1 yo: 18-25 cm/y
- 1-2 yo: 10-12 cm/y
- 2-3 yo: 8-10 cm/y
- childhood: 5 cm/y (small deceleration before onset of puberty)
- adolescence: 6-9 cm/y (but this is variable)
What is the best way to monitor effectiveness of thyroid replacement in autoimmune thyroiditis?
Monitor TSH
-autoimmune thyroiditis: lymphocytic infiltration of thyroid gland
What is the most common form of inheritance of primary nephrogenic DI?
X-linked inheritance
- more common in males (90%)
- mutation in AVPR2 gene
What is the most common cause of thyroid disease in children?
-what is the most common antibodies seen in this condition (3 in total)?
Hashimoto’s aka lymphocytic thyroiditis aka autoimmune thyroiditis
- MOST COMMON cause of thyroid disease in children
- T cell lymphocytes infiltrating thyroid gland
- hyperplasia first (can get hyperthyroidism) and then follicular cells die (hypothyroidism)
- anti-thyroperoxidase antibodies most common (90%); can also have anti-thyroglobulin antibodies (10%) and anti-thyroid receptor antibodies
What is the treatment for Hashimoto’s thyroiditis?
- If hypothyroid: levothyroxine
- If euthyroid: monitor with no treatment
What are the indications for growth hormone (6)?
- Turner’s syndrome
- Idiopathic short stature with severe functional impairment secondary to short stature
- Prader Willi
- Growth hormone deficiency
- Chronic renal failure
- SGA with short stature
What are the possible side effects of growth hormone (4)?
think what obese people are at risk of getting
- SCFE
- Pseudotumor cerebri
- Gynecomastia
- Worsening scoliosis
Is precocious puberty more common in boys or girls?
-what is the most common etiology in this group?
Girls!
-most common etiology is idiopathic
What is the differential diagnosis for virilized female baby?
- 3-B-hydroxysteroid-dehydrogenase deficiency
- CAH (21 hydroxylase deficiency
- Maternal androgen exposure (maternal adrenal tumor)
What is the differential diagnosis for an undervirilized male?
- Defect in androgen synthesis (3-B-hydroxysteroid-dehydrogenase or 5-alpha reductase deficiency)
- Androgen insensitivity syndromes (receptors do not respond to testosterone)
- Syndromes with defect in testicular malformation
- Deny-Drash: nephropathy, bilateral Wilm’s and ambiguous genitalia
- WAGR
What are the clinical features of hypoparathyroidism (5)?
- Hypocalcemia
- Delayed teeth eruption/strength
- Scaly skin
- ***Mucocutaneous candidiasis
- Cataracts
* **All from hypocalcemia
What are the exam findings of hypocalcemia (6)?
- Muscle spasms
- Chovstek’s sign: facial nerve spasm on tapping
- Trousseau’s: hand spasm with blood pressure cuff inflated
- Seizures
- Tetany
- Hyperreflexia
What hormones is secreted by the anterior pituitary gland?
FATPIG F - FSH/LH A - ACTH T - TSH PI - prolactin G - GH
What are the two hormones secreted by the posterior pituitary gland?
- Oxytocin
2. ADH
How do you distinguish between primary and secondary adrenal insufficiency on clinical features and labwork?
Primary adrenal insufficiency: adrenal gland dysfunction
- elevated ACTH
- low cortisol or low mineralcorticoid (hyponatremia/hyperkalemia)
- will see hyperpigmentation (due to pituitary gland trying to stimulate the adrenals and also secreting MSH)
Secondary adrenal insufficiency:
hypothalamic or pituitary dysfunction
-low ACTH
-low cortisol, normal mineralocorticoid (controlled by RAAS system, not hypothalamus or pituitary; thus no hyponatremia/hyperkalemia)
What is the differential diagnosis for primary adrenal insufficiency (5)
- Autoimmune: isolated, autoimmune polyendocrinopathy syndromes
- Infectious: meningococcemia, disseminated fungal infections, TB
- Trauma: bilateral adrenal hemorrhage
- Inherited enzymatic defects: CAH
- Iatrogenic: exogenous steroids
What conditions should be screened for in obese patients? (8)
- Hyperlipidemia
- Obstructive sleep apnea
- Type 2 DM
- Hypothyroidism
- SCFE
- Intracranial hypertension
- PCOS
- Accelerated growth secondary to increased estrogen
What is the diagnostic criteria for PCOS?
- Anovulation or oligoovulation
- Hyperandrogenism
- Polycystic ovaries on U/S (not required to make the diagnosis)
What are clinical features of rickets?
General:
- FTT
- Fractures
- Frontal bossing
- Delayed anterior fontanelle closure
- Delayed eruption of teeth
- Craniotabes (soft, thin skull)
Chest:
- Ricketic rosary: prominent knobs of bones at costochondral joints
- Harrison’s groove: diaphragm pulls weakened bones downward
- Atelectasis
Wrist:
1. Widening of wrist
How do you calculate mid parental height?
Girl: [(mom’s ht in cm + dad’s ht in cm) - 13 cm] / 2
Boy: [(mom’s ht in cm + dad’s ht in cm) + 13 cm] / 2
Which is the only pituitary hormone that is suppressed by a hypothalamic factor?
Prolactin - inhibited by hypothalamic release of dopamine
-thus, in hypothalamic deficiency, you get a decrease in most pituitary hormone secretions but can have increase in prolactin secretion
In a baby born with ambiguous genitalia, what is the most important thing to do on exam?
Establish whether there are palpable gonads in the scrotum or inguinal canal
-if you feel testicles, Y chromosome is more likely
Broadly, what are the 3 causes of ambiguous genitalia in a male patient (XY chromosome on karyotype)?
-useful investigations?
- Defective adrenal production of androgens
- Lack of proper testicular testosterone synthesis
- ie: 5 alpha reductase deficiency = inadequate conversion of testosterone to DHT leaing to ambiguous external genitalia but normal internal genitalia - Failure of target tissues to respond to androgens
- complete vs. partial androgen insensitivity
- complete: presents in adolescence since child appears phenotypically female and when reaches adolescence, amenorrhea is noted
- partial: has ambiguous genitalia thus is diagnosed at birth
- useful investigations: testosterone and DHT (dihydrotestosterone) levels
What are the 2 most common causes of ambiguous genitalia in a female patient (XX chromosome on karyotype)?
Virilization occurs when the female fetus is exposed to excessive androgens; since mullerian inhibiting substance is not present however (secreted only by testicles which only develop when there is a Y chromsoome), female internal reproductive organs are normal
- Congenital adrenal hyperplasia
- Maternal exposure to exogenous androgens
What are potential sources of maternal androgens that could contribute to virilization of a female baby?
- Use of progestins during pregnancy
- Ovarian or adrenal tumors
- Maternal CAH