Endocrinology q-bank Flashcards
Which antibodies are most commonly seen in Hashimoto thyroiditis?
Thyroid antiperoxidase antibody (anti-TPO) and antithyroglobulin antibody seen in 90% of patients
What should you consider in a patient with hypoparathyroidism, Addison’s, recurrent candidiasis and skin changes?
APCED Auto-immune polyendocrinopathy ectodermal dysplasia - autoimmune polyendocrinopathy, candidiasis, ectodermal dysplasia
With nephrogenic DI, what is the most common inheritance pattern? Name 4 acquired causes of nephrogenic DI.
X-linked, some forms can be AD or AR Acquired causes: hypercalcemia hypokalemia lithium rifampin methicillin kidney disease
In physiologic adrenarche, describe: - age at which acceptable - what blood / urine markers are seen - bone age findings - long-term prognosis - tests to perform if unsure if physiologic
Adrenarche (increase in adrenal steroids) resulting in hair, body odour and skin changes and maybe slight growth acceleration but no other signs of puberty - 6 years of age in boys and girls - rise in DHEAS, urine 17-ketosteroids (hydroxysteroids normal) - bone age on upper end of normal - more likely to develop PCOS or hyperandrogenism - ACTH stim test with 17-OHP (rule out atypical CAH)
What is Russel-Silver syndrome?
A growth disorder from before and after birth: LBW & FTT, normal head size Low appetites and at risk of hypoglycemia Small triangular face, prominent forehead, downturned corners of mouth Delayed development, learning disabilities
What type of growth are these curves showing?
Constitutional delay of growth and adolescence
What form of growth?
Familial or genetic short stature
What form of growth?
Primary nutritional or severe chronic illness
What form of growth?
Congenital GH deficiency :)
Name a possible syndrome associated with this type of growth
Turner’s
What is the calculation for expected height range in kids?
(based on parents)
(Mum’s height + dad’s height) +/- 13cm if boy/girl
divided by 2
Range calculated as +/- 10cm
What is the rate of growth in both sexes?
4-7 cm/year
When are kids ‘allowed’ to cross percentile lines on the growth chart?
1- within first three years of life while finding their fit (ie: small infants to large parents and vice versa)
2- at puberty (accounting to different start times of growth spurts)
What is IGF1?
Insulin like Growth Factor 1
factor produced by growth hormone’s effect on the liver
What is the significance of bone age?
Where to measure?
Most conditions that cause poor linear growth also cause a delay in skeletal maturation and retarded bone age, it indicates that the short stature is to some extent reversible.
A bone age that is NOT delayed is of greater concern and can be diagnostic ie: syndromes, achondroplasia, rickets
Measure at hand and wrist epiphyseal maturation centers
What investigations to consider in a well nourished child with a deceleration in linear growth?
TSH, T4
bone age
karyotype if female
IGF-1, IGFB3
(if considering glucocorticoid excess: 24h urinary free cortisol & creatinine)
Approach to decelerating linear growth in a thin child?
Consider primary GI, nutritional, renal or other systemic chronic disease:
CBC w/ ESR
TTG
electrolytes
first morning void
What findings suggest growth hormone deficiency:
in the neonate? (try 4)
in the child? (try 3)
neonate: 1- hypoglycemia, 2- prolonged jaundice, 3- hepatitis, 4- microphallus, 5- traumatic delivery
child: 1- cranial irradiation, 2- head trauma or CNS infection, 3- cosanguinity or affected family member, 4- craniofacial midline abnormalities
What growth findings would suggest GH deficiency?
severe short stature (< 3 SD below)
height < 2 SD and height velocity <1 SD
Indications for GH treatment approved by FDA
GH deficiency
Turner’s
Chronic Renal Failure
Idiopathic short stature
SGA with short stature
Prader Willi
Define central precocious puberty & tests to investigate
Onset of secondary sexual characteristics:
development on breasts before the age of 8 in girls
development of testicular volume >4mL before the age of 9 in boys
Order bone age, FSH/LH/estradiol/testosterone
If +ve, consider GnRH stim test and cranial imaging in boys or girls <6yo
Who do you worry more about with precocious puberty, girls or boys?
BOYS!
90% of girls have the idiopathic form
75% of boys will have a structural CNS abnormality
How do you treat central precocious puberty?
(assuming work-up negative)
GnRH agonist in order to disrupt pulsatility
ie: Leuprolide acetate (Lupron)
Actual adult height of patients followed is 1 SD less than mid-parental height
What is the most common form of congenital adrenal hyperplasia?
What lab findings?
‘Salt-losing form’ 70% of CAH
21-hydroxylase deficiency (90% of CAH cases) therefore accumulation of 17-OHP as it can’t be converted to 11-deoxycorticosterone and 11-deoxycortisol (aldosterone and cortisol precursors)
Presents with hyponatremia, hyperkalemia, hypoglycemia, metabolic acidosis, vomiting, lethargy, shock at 10-14 days of age
When do virilized females with CAH get operated?
What to do with subsequent pregnancy in mum?
They get operated at 2-6 months.
Subsequent pregnancies can be treated with dexamethasone in order to suppress fetal androgen production and lessen external genitalia virilization. Once CVS can be done, continue treatment only if the fetus is a female.
When do boys with ‘simple virilizing’ CAH generally present, and with what?
‘Simple virilizing’ form 30% of CAH
Often not diagnosed until 3-7 years of age when excess androgens have already caused accelerated linear growth +/- excessive muscular development, pubic and axillary hair, acne and deep voice, prepubertal testes (skeletal maturation up to 5 years in advance of chronological age, ends up with shorter adult height because of premature closure).
Name the most common disorders of sexual differentiation
virilizing CAH (14%)
androgen insensitivity syndrome (10%)
mixed gonadal dysgenesis (8%)
clitoral / labial anomalies (7%)
hypogonadotropic hypogonadism (6%)
46 XY SGA with hypospadias (6%)
Suggested approach to abnormal sexual differentiation?
1) history and physical, ***palpable gonads
2) investigations:
a) karyotype
b) blood tests: 17OHP, androstenedione, gonadotropin levels, molecular testing for SRY
c) internal anatomy evaluation with US, endoscopic GU exam, VCUG, CT or MRI
Describe the pathophysiology, physical and lab findings of androgen insensitivity syndrome
mutation in androgen receptor gene, X-linked recessive, most common male DSD
phenotypic spectrum with complete AIS presenting as phenotypic females and normal appearing males with simply infertility
46X-Y, testes, normal or elevated LH and testosterone (&DHT) levels, vagina ends in blind pouch (no other female internal organs). At puberty breast development but no menstruation and no sexual hair. Adult height that of male XY.
Replacement therapy with estrogens indicated at puberty.
What are the features of Denys Drash syndrome?
WT1 gene mutation
Nephropathy, bilateral Wilms tumour, ambiguous genitalia in XY with undescended testes
What are parathyroid hormone’s effects?
Symptoms of hypoparathyroidism?
In response to low serum calcium and high phosphate: PTH turns on and increases calcium, decreases phosphate.
Symptoms related to hypocalcemia: MSK cramps and pain, numbness, Chvostek & Trousseau, convulsions, ICP/headache/papilledema, cataracts