Endocrinology Flashcards
What is the main hormone that triggers puberty?
LH
~1- 3 yr before onset clinically evident puberty, LH levels become detectable during sleep in pulsatile pattern
What are the cut offs for precocious puberty in boys and girls?
Boys <9 years (early puberty is more pathologic)
-NOTE: Onset of puberty= testicular enlargement
Girls <8 years (THELARCHE)
-NOTE: Onset of puberty=thelarche
What are the cut offs for delayed puberty in boys and girls?
Girls > 13 (thelarche), >15 (menses)
NOTE: Late puberty rare in girls, commonly organic
Boys > 14
What is the first clinical sign indicative of hypothalamic-pituitary-gonadal activation in girls and boys?
Girls-breast buds
Boys-testes volume (>4ml) or length >2.5 cm
Describe SMR staging for girls (breasts)?
Stage 1: Prepubertal, with no palpable breast tissue
Stage 2: Breast bud, with elevation of the papilla and enlargement of areolar diameter
Stage 3: Enlargement of breast, without separation of areolar contour from breast
Stage 4: Areola and papilla project above the breast, forming a secondary mound.
Stage 5: Recession of the areola to match contour of breast, with papilla projecting beyond contour
Describe SMR staging for boys (genitals)?
Stage 1: Prepubertal. Testicular volume <1.5ml, penis <3 cm
Stage 2: Enlargement of scrotum and testes (testicular volume 1.6-6ml); scrotal skin reddens and changes in texture
Stage 3: Enlargement of penis (to about 6 cm); further growth of testes (6-12 ml)
Stage 4: Increased size of penis (10cm) with growth in breadth and development of glans; testes (12-20 ml) and scrotum larger, scrotal skin darker
Stage 5: Adult genitalia (testicular volume 20 ml), penis 15 cm
What is a differential diagnosis of precious puberty?
Central:
- Idiopathic (95% in girls, only 50% in males)
- CNS lesions-hypothalamic hamartomas, brain tumour
Peripheral: A. Girls -Ovarian cyst -Ovarian tumor -McCune Albright -Prolonged untreated hypothyroidism) -Exogenous estrogen/testosterone -Severe longstanding hypothyroidism -CAH -Estrogen-secreting adrenal tumour -McCune Albright
B. Boys
- Leydig cell tumour
- Adrenal (CAH, adrenocortical tumor)
- hCG secreting tumour
- Familial male precocious puberty
- Severe longstanding hypothyroidism
- Exogenous testosterone
- CAH
- Androgen-secreting adrenal tumour
What is premature adrenarche?
Due to early maturation of adrenal androgen production
Benign, non-progressive pubertal variant
What bloodwork might you do for premature adrenarche?
- Bone age: (mild to moderate increase, but should NOT be >2 years)
- DHEAS normal or mildly increased
- LH, FSH-prepubertal
- Consider 17-OHP and testosterone to r/o ddx (adrenal/ovarian tumours, CAH, exogenous androgens)
How do you differentiate premature adrenarche from peripheral precocity?
Premature adrenarche:
Associated with increased weight
True puberty at normal age
Normal penile length
Precocity:
Bone age >2 years advanced
Marked hyperadrogenism (e.g. clitoromegaly)
Can have longer penile length (because of excess testosterone)
What is premature thelarche?
Onset 6-24 mo
Isolated to breast development
Benign non-progressive pubertal variant
How do you differentiate premature thelarche from precocious puberty?
Premature thelarche:
- No height acceleration
- Most will regress
- True puberty at normal age
- SMR <2
Preciocious puberty:
- SMR >3 breasts
- Advanced bone age
Does premature adrenarche increase the risk of PCOS?
YES
What investigations should you order for premature thelarche?
Bone age
Continued observation for GV and secondary sexual characteristics
How do you test for familial male limited precocious puberty?
Genetic testing LHCGR
If you see discrepancy and penis size/pubic hair and testicular growth, is this more indicative of central or peripheral precocity?
Peripheral
Excess androgen causes penis to enlarge, pubic hair
However, FSH is supressed so there is no stimulation of Sertli cells to cause testicular enlargement
What are the clinical manifestations of McCune Albright?
- Usually girls
- Precocity (ovaries/testes are autonomously producing hormones)
- Patchy hyperpigmentation
- Polyostotic fibrous dysplasia
- Other endocrinopathies (hyperthyroidism, GH excess, cushing’s syndrome)
- Renal phosphate wasting (leading to osteomalacia)
- Episodic puberty-cyclic breast enlargement and vaginal bleeding
What initial tests do you order for peripheral precocity
Girls: bone age, TSH, LH, FSH, estradiol, GnRH stim testing → AUS for peripheral, MRI brain for central
Boys: bone age, TSH, LH, FSH, testosterone, GnRH stim, imaging essential MRI/CT brain
When do you do an MRI for precocious puberty?
All boys with precocity
All girls <6 with precocity
What is the most sensitive test to determine onset of puberty?
Basal LH > 0.3 IU/L
What is a differential diagnosis of delayed puberty in girls?
Hypogonadotropic hypogonadism:
- CDGP***most common
- Chronic disease (e.g. anorexia, cystic fibrosis, IBD)
- Tumour
- Radiation
- Head injury
- Kallman syndrome
- CHARGE syndrome
Hypergonadotropic hypogonadism: Turner syndrome Ovarian radiation POF (Galactosemia Fragile X) Complete AIS Chemo
What is the differential diagnosis of delayed puberty in boys?
Hypogonadotropic hypogonadism:
- CDGP ***most common
- Chronic disease (e.g. anorexia, cystic fibrosis, IBD, malnutrition)
- Kallman syndrome
- Pituitary tumour
- Head injury
- CHARGE syndrome
Hypergonadotropic hypogonadism:
- Klinefelter syndrome
- Testicular torsion/trauma
- Vanishing testes syndrome
- Chemo
- Gonadal infection
- Gonadal dysgenesis
What test would you order if you were concerned about hypergonadotropic hypogonadism?
Chromosomes
To look for Klinefelter in boys, Turner in girls
What are the goals of precocious puberty treatment?
Preserve adult height
Alleviate psychosocial concerns
How do you treat precocious puberty?
GnRH agonist (Lupron)-continuously given so downregulates LH, FSH
What is the definition of primary amenhorrhea?
Absence of menses by 15 years or >3 years after thelarche
What is the definition of secondary amenorrhea?
Absence of menses for 3+ months in women with regular cycles; 6 months in women with irregular cycles
What is the differential for primary amenorrhea?
Hypothalamic and pituitary disease
- Functional hypothalamic amenorrhea
- Isolated GnRH deficiency
- Constitutional delay of puberty
- Hyperprolactinemia
- Other
Gonadal dysgenesis/POI
- Turner syndrome
- 46,XY gonadal dysgenesis
- Primary ovarian insufficiency (POI)
Polycystic ovary syndrome
Outflow tract disorders
- Imperforate hymen
- Transverse vaginal septum
- Müllerian agenesis
Receptor abnormalities and enzyme deficiencies
- Complete androgen insensitivity syndrome
- 5-alpha-reductase deficiency
- 17-alpha-hydroxylase deficiency
- P450 oxidoreductase deficiency
- Estrogen resistance
What tests would you order for McCune Albright?
Screen for other endocrinopathies
When is anovulation most common?
Within first 2 years of menses
List 5 conditions causing DELAYED bone age
Constitutional growth delay GH deficiency Hypothyroidism GI disease (celiac, crohns) Rheumatologic disease (JIA) Renal disease (CKD, RTA) Cancer Immunodeficiency Pulmonary disease Malnutrition
List 3 conditions causing with ADVANCED bone age
Precocious puberty
Excessive androgen production
Hyperthyroidism
CAH
Describe the features of Androgen Insensitivity Syndrome?
Overall- normal appearing female with brests, no menses, no pubic hair, with internal male genitalia
- Female phenotype, but 46 XY karyotype
- Normal breast development (from peripheral conversion of T)
- Primary amenorrhea
- Little or no axillary or pubic hair
- Absent uterus, but testes present
- Blind vaginal pouch on exam (no upper 1/3)
- Male height
How many years after thelarche do you normally get menses?
2 years
Describe normal sex development in males
- Bipotential gonad
- Y chromosome-SRY
- Testis development
- Sertoli cells produce AMH, which degrades Mullerian duct, resulting in no uterus
- Leydig cells produce testosterone, which develops Wolffian duct, resulting in male internal genitalia
- Testosterone also converted to DHT to create male external genitalia
Describe normal sex development in females
- Bipotential gonad
- No Y chromosome
- Gonad becomes ovary (produce estrogen and progesterone)
- No AMH or Testosterone produced
- Mullerian duct turns into internal female genitalia and wolffian duct degenerates
What does DSD look like in males?
Bilateral UDT
Bifid scrotum
Hypospadius
What does DSD look like in females?
Clitoromegaly
Single genitourinary opening
Inguinal hernia
What are the different categories of DSDs?
1) Sex chromosome DSD
2) 46 XY DSD
3) 46 XX DSD
What are the sex chromosome DSDs?
- Turners (45,X)
- Klinefelter (47, XXY)
- Mixed gonadal dysgenesis/ovotesticular DSD (45, X/46, XY)
- Chimeric ovotesticular DSD
(46,XX/46,XY)-BOTH ovaries and testes tissue are present.
When would you think about a mixed gonadal dysgenesis?
When there are asymmetric findings (unilateral ovary/testes, half a uterus)
What are the most common 46 XY DSDs?
The ones you need to know:
- 5 alpha reductase
- AIS
Comprehensive differential:
- Disorders of gonadal development
- Complete gonadal dysgenesis (female phenotype)/Swyer syndrome
- Partial gonadal dysgenesis
- Vanishing testes syndrome
- Ovotesticular DSD
- Others: WAGR, campomelic - Disorders in androgen synthesis
- Androgen biosynthesis defect (e.g. 17 hydroxysteroid dehydrogenase deficiency, 5alpha reductase deficiency, StAR mutation) - Defect in androgen action (e.g. PAIS, CAIS)
- LH receptor defects (e.g. Leydig cell hypoplasia)
- Disorders of AMH and AMH receptor (e.g. Persistent Mullerian Duct syndrome)
Other
e.g. severe hypospadius, cloacal extrophy
What are the clinical features of complete gonadal dysgenesis (46,XY)?
Infertile phenotypic female (normal external and internal female structures) with streak gonads
What is the genetics of AIS?
X-linked
What is the phenotype of 5-alpha reductase deficiency?
Internal genital male
External genitalia female
Most common phenotype: -Small phallus Bifid scrotum Urogenital sinus with perineal Hypospadias Blind vaginal pouch Testes present
What is the most common 46, XX DSD?
Most common:
-Virilizing CAH (usually 21-hydroxylase and 11-hydroxylase)
Comprehensive differential:
Disorders of gonadal development
- Ovotesticular DSD
- Testicular DSD (e.g. SRY+)
- Gonadal dysgenesis
Androgen excess
- CAH-21 hydroxylase deficiency, 11-hydroxylase deficiency
- Aromatase deficiency
Other
- Cloacal extrophy
- Vaginal atresia
- MURCS
- Maternal androgenic medications during pregnancy
- Virilizing maternal tumours
What investigations should you order for DSDs?
- Karyotype with rapid determination of sex chromosomes within 24-48h
- Screen for CAH → 17-OHP, androstenedione
- Screen for androgens and precursors
- Screen for gonadal response to gonadotropin if suspected to have testes (inject HCG and measure androgens before/after)
- Genetic analysis for SRY
- Gonadotropin levels
- Imaging of internal anatomy starting with pelvic U/S
o Presence of a uterus and absence of palpable gonads usually suggests a virilized XX female
o Absence of a uterus, with or without palpable gonads, almost always indicates an under virilized male and an XY karyotype
o Also consider VCUG, endoscopy, renal/adrenal ultrasound, pelvic CT or MRI if needed
If gonads are palpable, what is the most likely type of DSD?
46 XY
If gonads not palpable, what is the most likely type of DSD?
46 XX (CAH)
What are the types of CAH?
1) Salt wasting 70%
2) Simple virilizing (glucocorticoid deficiency)
3) Non-classical (late onset)
What are the factors that affect gender assignment?
Diagnosis Genital appearance Surgical options Need for life long replacement therapy Potential for good sexual function Views of the family Potential for fertility
Baby with ambiguous genitalia and palpable gonads most likely has….
Partial AIS (vs. 5 alpha reductase)
Child with hypospadius, enlarged phallus and non-palpable testes?
Think 46, XX
CAH
In the first year of life, what is the main factor affecting growth?
Nutrition
GH independent
When do IUGR babies have catch up growth?
Weight by 2 years
Height by 2.5 years
How do you calculate mid parental height
Boys: (father’s height + mother’s height) / 2 + 6.5 cm +/- 8.5 cm
Girls: (father’s height + mother’s height) / 2 - 6.5 cm +/- 8.5 cm
What are 4 key questions to ask in short stature?
1) Is the child short?
- If ≤2.3% should have evaluation
- If >2.3% no further workup unless dropping %iles, dysmorphic features, or evidence of systemic disease
2) Is height velocity impaired?
- Growing < 5 cm/yr age 2-6, <4 cm/yr from age 6 to puberty
- Normal HV: usually nonpathologic SS (FSS, CSS),
- Abnormal HV: more likely to have pathologic SS (malnutrition, GH deficiency, cortisol excess, hypopit)
3) What is projected adult height (MPH), i.e. is growth in range for the family?
- If projected height ≤ 8.5 cm below MPH, then considered within range for family
4) What is the bone age? i.e. is there evidence of delayed or accelerated growth?
- Delayed BA: CS, nutritional deficiency, underlying systemic disease (e.g. IBD), and endo SS
- Differentiate based on HV
- Kids with CSS, have low-normal HV appropriate for BA, until reach pubertal BA, when speeds up
- Kids with systemic or endocrine disease have progressive ↓s in HV
- Normal BA: FSS, Turner, skeletal dysplasia, early systemic disease
- Advanced BA: Precocious puberty, hyperthyroidism; usually have accelerated early growth but epiphysial closure results in SS as adult
Additional questions:
1) Was the growth retardation prenatal or postnatal in onset?
- If IUGR, unlikely to be GH, T4
- Consider chromosomal, genetic, TORCH
2) Is the child proportionate or disproprtionate?
- Disproportionate:
- Short limbs: Rickets, epiphyseal dysplasias, achondroplasia
- Short trunk: kyphoscoliosis, spinal irradiation
What is normal growth velocity?
Age 3-Pubertal
>5 cm/year=normal
<4 cm/year=abnormal
Puberty
8-10 cm/year
How do you differentiate between familial short stature and constitutional delay?
FSS
- Normal growth velocity
- Parents short
- Bone age normal
- Normal puberty
- Short final height
CDGP
- Delayed growth velocity 6-36 months, then normal through prepubertal childhood, then catch up at puberty
- Height is normal for bone age (not chronologic age)
- Family hx delayed growth/puberty
- Bone age delayed
- Puberty delayed
- Normal final height
What are some red flags for endocrine disorder causing short stature?
Decline in growth velocity with preservation of weight
Delayed bone age
Delayed puberty
What investigations should you order for short stature if child has decreased height velocity or height >2.5 SD below mean?
Bone age
CBC, ESR
Creatinine, lytes, bicarb, Ca, PO4,ALP, albumin
TSH, fT4
Karyotype in females
IGF-1 and IGFBP-3 (IGFBP-3 has higher sensitivity in children <10 years)
Anti-TTG+IgA
Others:
Morning LH, FSH (if precocious puberty)
MRI+gad (for children with established GH deficiency, signs of HPA dysfunction, or midline defects)
How do you diagnose GH deficiency?
Slow height velocity Delayed bone age Low IGF-1 GH stimulation test Exclude hypothyroidism (because GH secretion requires intact thyroid function!)
What are red flags for short stature?
Cross percentiles Decreased GV Short for family heights Disproportionate Dysmorphic Lower height than weight percentile
List 5 indications for growth hormone therapy
GH deficiency Growth failure in CKD SGA with failure of catch up growth Turner's syndrome Idiopathic short stature with ht <2.25 SD
Before puberty what is the growth velocity?
Slows down (4-6 cm/year)
Describe the mechanisms of calcium regulation
1) Calcium in diet
2) Calcium sensing receptor in parathyroid gland will release PTH if Ca low
3) PTH’s job is to keep Ca normal at the expense of everything else (PO4, bone); main action is to activate Vitamin D
4) Vitamin D is stored as 25–Vitamin D. It is activated to 1, 25 Vitamin D by 1-alpha hydroxylase in kidney (activated by PTH)
5) Vitamin D increases gut absorption of Calcium
What do Vitamin D and PTH do to Ca and PO4?
PTH increases Ca and decreases PO4
Vitamin D increases Ca and PO4
In vitamin D deficiency, what happens to Ca, PO4 and PTH?
Low/normal Ca (because of secondary hypoparathyroidism)
Low phosphate
High PTH
What are the causes of hypoparathyroidism?
Parathyroid hypoplasia/aplasia
- DiGeorge
- Maternal DM
Autoimmune parathyroiditis
-Isolated or with type 1 autoimmune polyendocrinopathy
Infiltrative lesions
- Hemosiderosis
- Wilson’s
Post-surgical/post radioactive ablation
PTH receptor defects
-Pseudohypoparathyroidism
Causes of hypocalcemia
Vitamin D deficiency
Hypoparathyroidism
Rare causes:
Inadequate dietary intake
Redistribution (hungry bone syndrome, TLS, acute pancreatitis, osteopetrosis)
Causes of vitamin D deficiency
Poor dietary intake Lack of sunlight Malabsorption (CF, celiac, IBD) Maternal vit D deficiency Severe liver disease Renal failure Increased catabolism of VitD (AEDs-phenobarb, phenytoin) Hereditary 1, 25 OH resistance 1-a-hydroxylase deficiency
What doses of Vitamin D are recommended?
0-1 year-400 IU
1-3 years-600 IU
4-18 years- 600-1000IU
What formulation of vitamin D do you give in vitamin D deficiency and hypoparathyroidism?
Vitamin D deficiency-25-OH D (cholcalcefirol)
Hypoparathyroidism-1,25(OH)D (alfacalcidiol)
What is an appropriate dose of calcium supplement?
50-100 mg/kg/day
What are causes of hypercalcemia?
Hyperparathyroidism
- Parathyroid Adenoma/Hyperplasia
- MEN1
Excess vitamin 1, 25 D
- Subcutaneous fat necrosis
- Granulomatous disease (activated macrophages secrete 1-alpha hydroxylase)
- Vitamin D intoxication
- Sarcoidosis
- TB
Increased bone turn over
- Immobilization
- Hyperthyroidism
- Tumours
Other
- Familial Hypocalciuric Hypercalcemia
- William’s syndrome
What are causes of hyperparathyroidism?
Primary
- Parathyroid Adenoma/Hyperplasia
- Genetic syndromes like MEN1
Secondary
Tertiary
-Longstanding hyperparathyroidism progresses to autonomous secretion of parathyroid
PTHrP tumours
What are the features of William’s syndrome?
Cocktail personality Supravalvular aortic stenosis Short stature Recurrent ear infections, hearing loss Increased laxity, low msucle tone Hypercalcemia
How do you treat hypercalcemia?
Hyperhydration
DO NOT give lasix
Low calcium diet
Bisphosphanates
- Decreases osteoclast acivity
- Takes 48-72 hours to see effect
Calcitonin
- Only works for short time
- Decreases bone resportion
- Mild increase in urinary Ca
Steroids
- If excess 1, 25 Vit D
- Inhibits conversion of 25 to 1, 25 Vit D
What is difference between osteomalacia and ricket’s?
- Osteomalacia=undermineralization of bone osteoid
- Requires adequate Ca and PO4
-Rickets=Disease of growing bone that is due to poorly mineralized matrix at the growth plates
List 5 clinical features of Rickets
- Craniotabes
- Delayed closure of fontanelles
- Frontal bossing
- Delayed dentition; caries
- Craniosynostosis
- Rachitic rosary (widening of costochondral junctions)
- Harrison groove (depression of lower anterior chest from diaphragm pulling softened ribs)
- Respiratory infections and atelectasis (soft ribs impairs air movement)
- Enlargement of wrists and ankles (large growth plates)
- Valgus or varus deformities
- Windswept deformities
- Fractures
- Delayed motor milestones
What are the two types of rickets?
Calcipenic rickets
Phosphopenic rickets
Radiographic features of rickets?
Growth plate thickening
Edge of metaphyseal border loses sharpness (fraying)
Concave surface of growth plate (cupping)
Widening of metaphysis.
http://www.learningradiology.com/archives04/COW%20088-Rickets/ricketscorrect.htm
What are the causes of calcipenic rickets?
Vitamin D deficiency
- Inadequate intake/sun exposure
- Malabsorption
- Increased catabolism
- 1-alpha hydroxylase deficiency
- Vitamin D receptor problem
Calcium deficiency
- Inadequate intake
- Increased urinary losses
What are the causes of phosphopenic rickets?
- Inadequate intake
- Malabsorption
- Renal phosphate wasting
- Fanconi
- Dents
- Antiseizure meds - Genetic hypophosphopenic rickets (X-linked, AD, AR)
- Overproduction of phosphatonin
- Tumor-induced rickets
- McCune-Albright syndrome
- Epidermal nevus syndrome
- Neurofibromatosis
How do you differentiate calcipenic vs phosphopenic rickets?
Main differentiating factor is PTH. Elevated in calcipenic rickets, low/normal in phosphopenic rickets
Phosphate not helpful in differentiating (in calcipenic because of secondary hypoparathyroidism)
Calcipenic rickets
Vitamin D deficiency: ++ALP, -/N Ca, -/N PO4, +PTH, -25OHD
Calcium deficiency: ++ALP, -/N Ca, -/N PO4, +PTH, N 25 OHD
Phosphopenic rickets
Nutritional deficiency: +ALP, N Ca, -PO4, -/NPTH, N 25OHD
Renal tubular PO4 wasting: +ALP, N Ca, -PO4, -/NPTH, N 25OHD
Genetic hypoPO4 rickets:
+ALP, N Ca, –PO4, +/NPTH, N 25OHD
What is the biochemical marker of rickets?
ALP=increased bone turnover of undermineralized bones
What is the best test for nutritional vitamin D deficiency?
25 Vit D
1, 25 Vit D is activated form–rarely need to test
What 4 investigations would you order for rickets?
Ca, PO4, ALP, PTH, 25-OHD
Rickets survey (hands and knees)
NOTE: best test for rickets is 25-OHD
All are seen in hyperparathyroidism except: Hyporeflexia Increased ICP Carpopedal spasm Candidiasis Nonspecific EEG changes
Hyporeflexia
Hyperparathyroidism can be seen in all except: Primary proximal renal tubular acidosis Vitamin D deficient rickets Rickets with liver failure Rickets with anticonvulsants
Primary proximal renal tubular acidosis-PTH is normal/low
With liver failure and anticonvulsants, you get vitamin D deficiency, which results in secondary hyperparathyroidism
What is the active form of thyroid?
T3
For primary thyroid disorder, what is the best thyroid function test to use?
TSH
Doing just a fT4 would miss a compensated hypothyroidism
For central hypothyroidism, what is the best thyroid function test to use?
fT4
What are causes of congenital hypothyroidism (3 categories)?
1) Dysgenesis-85%, abnormal development (e.g. ectopic thyroid, aplasia, hypoplasia)
2) Inborn errors of metabolism (dyshormonogenesis)-15%
3) Maternal antibiodies-2% transplacental maternal thyrotropin-receptor blocking antibody (TRBAb)
4) Maternal drugs: Iodides, Amiodarone, Propylthiouracil, Methimazole Radioiodine
When do you need to start treatment for congenital hypothyroidism?
Within first 7-14 days of life
When do you screen for congenital hypothyroidism?
DOL 3
What is an elevated TSH on newborn screening?
TSH >17
TSH>40=critical (start meds now and order nuclear sign!)
What do you do with an elevate d TSH 17-40 on newborn screening?
repeat TSH, fT4