Endocrinology Flashcards
What is the difference between thyroglobulin, thyroxine and free T4
How is thyroxine binding globulin deficiency inherited?
What will the lab values look like and what test can be done to diagnose it
Thyroglobulin is found only in the thyroid and is used to make thyroid hormones, thyroxine is inactive T4 it is bound to TBG, free T4 is unbound and active
It is X-linked
TSH will be normal but T4 or thyroxine levels will be low, newborn screen measures thyroxine levels, not free T4, get a free T4 which will be normal or TBG level which will be low
Is any treatment necessary for thyroxine binding globulin deficiency?
How do you screen for hypothyroidism and congenital hypothyroidism?
What are signs of congenital hypothyroidism
What are the two most common causes of congenital hypothyroidism
No treatment is necessary if TSH is normal but T4 is low on a newborn screen
TSH level
Puffiness, large tongue, horse cry, umbilical hernia, hypotonia, large anterior fontanelle, constipation, modeling
Most common is dysgenesis, also it could be due to abnormal thyroid developmentIn utero
Which lab tests are positive and Hashimoto’s thyroiditis
What physical exam findings will be present
Positive anti-TPO, positive anti-thyroglobulin antibodies, low free T4 and elevated TSH
A painless firm goiter/thyromegaly
What will be the result of a radioactive iodine uptake test in Hashimoto’s
What should be done if TSH is abnormal on the newborn screen
It will be low because the thyroid is being destroyed and cannot take up iodine
Start levothyroxine immediately due to tremendous cognitive delays if therapy is not started by four weeks and also repeat the labs
A midline cystic lesion on the exam will almost always be white?
How do you diagnose it? Which two tests are done?
How is it treated
Thyroglossal duct cyst
Ultrasound and a thyroid scan to ensure thyroid gland is intact
If thyroid is functioning OK and not only in the cyst you can remove it surgically
What is a painless, mucus and cystic mass usually near the inner lips or under the tongue?
How is it treated?
Ranula
With surgical removal
How should a thyroid nodule be worked up in a child?
What is the method of choice for final diagnosis confirmation?
Get a TSH and free T4, low TSH suggests a hot nodule, get an ultrasound or radioactive iodine uptake to distinguish hot versus cold
Fine needle aspiration, cold nodules are usually bad
Describe the lab testing for Graves’ disease
What are signs and symptoms?
What tests can be done
How is it treated?
TSH will be very low due to the very high free T4 being released
Infiltrative ophthalmopathy, emotional Lability, weight loss, tachycardia, heat intolerance, lid lag
Radioactive iodine testing will be very high
Methimazole, propylthiouracil, iodine ablation, beta blocker like propranolol
How do PTU And methimazole work?
How can symptoms of hyperthyroidism Be disguised on the test?
Why is propothiouracil not first line
They inhibit the production of thyroid hormone, not the secretion
Hyperactivity, disorganized thinking, trouble sleeping
It can be hepatotoxic so it is not first line
Describe how neonatal thyrotoxicosis presents?
What is the cause and how frequent does it happen?
How do you treat this?
How do you differentiate neonatal thyrotoxicosis from an inborn error of metabolism?
Tremors, tachycardia, SVT in the immediate newborn.
It is due to maternal thyroid stimulating antibodies crossing over the placenta
Treat with PTU during the first trimester, methimazole is a teratogen, after that switch to methimazole to avoid potential hepatotoxicity you
Inborn error of metabolism do not result in symptoms within the immediate newborn. Like neonatal thyrotoxicosis does
Define hypercalcemia
What findings are on the EKG
What are presenting symptoms
What is the initial treatment?
Calcium level greater than 12
ST shortening, QT interval shortening
Polyuria from osmotic diuresis, nausea, vomiting, change in mentation, abdominal pain
IV hydration
Which three skeletal disorders can also cause hypercalcemia
How is hypercalcemia due to immobilization treated?
Dysplasias, skeletal immobilization, skeletal/body casting
Treat with IV fluids and loop diuretics
What is the mnemonic used to describe complications and associations with hypercalcemia
Bones like osteoporosis and osteomalacia, Stones like nephrolithiasis, abdominal grounds, psychiatric overtones such as,, delirium, depression, fatigue, psychosis
Define hypocalcemia
What are five symptoms of hypocalcemia
Calcium level less than 8.5 or ionized calcium Less than 4.5
Paresthesias, tetany like trousseaus sign or Chvostek sign, Seizures that do not respond to benzodiazepines, laryngospasm, prolonged QTC
What are four differentials for early hypocalcemia which occurs within the first three days of life
In the late hypocalcemia which occurs after seven days of life, what are four main causes
Asphyxia, infant of a diabetic mother, maternal hyperparathyroidism, intrauterine growth restriction
Did George syndrome/22Q 11 deletion, hypo parathyroidism, vitamin D deficiency, pseudohypoparathyroidism
Which electrolyte findings are present in hypo parathyroidism, how is it treated?
Describe pseudohypoparathyroidism and what are the PTH, calcium, phosphorus levels
What are three physical exam findings in pseudohypoparathyroidism as well
Low calcium high phosphorus
It is a autosomal dominant disorder which receptors are resistant to PTH, PTH will be high, calcium will be low, phosphorus will be high
Brachydactyly, Developmental delay, moon faces
How does late stage chronic kidney disease cause hypocalcemia?
Why does nephrotic syndrome cause hypocalcemia
Which Electrolyte must be corrected first before calcium can be corrected
Why does alkalosis cause hypocalcemia
What findings will be present in hyperventilation
Because vitamin D cannot be activated to its active form
Because of hypoalbuminemia, make sure to correct the calcium
Magnesium must be corrected first
Alkalosis shifts ionized calcium to the protein bound form resulting in less active/free calcium
Hyperventilation causes respiratory alkalosis, hypocalcemia due to the above reasonAnd paresthesias
Which alcohol can cause hypocalcemia
What do crystals in the urine look like caused by Etheline glycol poisoning?
Etheline glycol, Also look for calcium oxalate crystals
They look like rods or needles, compare this to the other type of oxalate crystals that look like a big X on the crystal
When looking for deficiency, which vitamin D do you check first?
If someone has a history of renal disease which do you check?
25 hydroxy vitamin D
1–25 hydroxy vitamin D
What are four situations which can present with vitamin D deficiency in children
Which anti-seizure medication can cause hypocalcemia
African-American breast-fed child, mom is not on the vitamin D supplementation
African-American breast-fed child whose mom is not getting enough sunlight
Child with symptoms of malabsorption
Child with a history of epilepsy who is on anti-seizure medication’s
Valproic acid
Which syndrome presents with normal or low calcium and low phosphorus
How is it inherited
What is the cause of this? How is it treated
What are the lab numbers for calcium, phosphorus, alkaline phosphatase, vitamin D 25,pth
Familial Hypophosphatemic rickets/Vitamin D resistant rickets
X-linked dominant
Defective phosphate reabsorption in the proximal tubule, defect in conversion of 25 vitamin D to 1–25 vitamin D
Treat with oral phosphate supplementation, avoid hypocalcemia with supplementation of vitamin D 1–25
Calcium is normal or low, phosphorus is low, alkaline phosphatase is high,Vitamin D 25 is normal, PTH is normal
How do you differentiate familial hypophosphatemic rickets from the initial phase of vitamin D depletion?
What will calcium, phosphorus, PTH levels be in severe vitamin D deficiency
They will both have normal calcium, low phosphorus but vitamin D 25 will be low in early vitamin D depletion, it will be normal in FHR
Low calcium, low phosphorus, high PTH
If you see low calcium with high phosphorus, what three differentials do you think of
If you see normal calcium and high phosphorus which three do you think of?
Hypo parathyroidism, pseudohypoparathyroidism, phosphorus overload
Renal disease, growth hormone excess or high phosphorus diet
How can liver dysfunction result in rickets?
The adrenal steroid synthesis pathway starts with which hormone?
It ends with which three possible hormones?
Decreased bile salts in the gut lead to decreased vitamin D absorption and deficiency which leads to low calcium 
It starts with progesterone
Ends with aldosterone, cortisol, adrenal androgens
Which symptoms are present in Cushing’s syndrome
What is the difference between Cushing’s syndrome and Cushing’s disease
Can a patient with Cushing’s syndrome be tall?
Poor growth/slow growth rate, striae, , Obesity, moon face, Buffalo hump, muscle weakness
Cushing disease is hypercortisolism due to a central cars where the syndrome is not
No, if they are tall and obese with stretch marks think high caloric intake
What is Addison’s disease?
What are some symptoms
What are ACTH levels like in this and what does this cost?
What is the result of an ACTH stimulation test in this disease
Adrenal insufficiency
Electrolyte shifts like potassium being high or hyponatremia causing weakness, myalgias, malaise, nausea and vomiting as well as hypoglycemia due to lack of cortisol
ACTH levels are high and this can cause hyperpigmentation due to increased melanin production
It will be negative, a normal response and cortisol rise will not occur
How can the levels of ADH look in Addison’s disease? Why is this?
Describe the electrolytes in Addison’s disease, why is this?
ADH can be high due to the body trying to raise blood pressure and conserve free water, this should not be diagnosed as SIADH
Hyperkalemia and hyponatremia due to aldosterone deficiency
What is the most common reason for adrenal insufficiency in children? What is the usual at theology
What are three causes of adrenal insufficiency?
Describe secondary adrenal insufficiency, will there be hyperkalemia and hyponatremia? Why?
Describe the results of an ACTH stimulation test in this
Slow autoimmune destruction of the adrenal gland
Infection, adrenal hemorrhage, idiopathic
This is a pituitary issue due to low ACTH, Electrolytes will be normal due to some production of aldosterone
ACTH stimulation will have increased levels of cortisol due to the fact that the adrenal gland is still functioning
What other physical findings is also sometimes associated with secondary adrenal Insufficiency
How do you treat primary adrenal insufficiency?
How do you treat secondary adrenal insufficiency
Midline defects, think that the pituitary is also midline
Hydrocortisone and fludrocortisone
Just hydrocortisone since the RA system is intact
Describe findings in an adrenal crisis including symptoms and electrolytes
How do you treat this
Nausea, vomiting, malaise, hyperkalemia, hyponatremia
Treat with saline, glucose, IV hydrocortisone
How will a boy with congenital adrenal hyperplasia be presented due to the elevated ACTH levels?
Which enzyme is deficient in CH on the boards
Which hormone will be high on the newborn screen to diagnose CAH
How will a baby present with CAH on the boards
Hyper pigmented scrotum
21 hydroxylase
17 hydroxyprogesterone will be high
Abnormal electrolytes like hyperkalemia and hyponatremia with shock like symptoms that resemble sepsis
How will a newborn girl be presented who likely has C8H?
What should you do if the newborn screen is abnormal but the physical exam is normal?
How do you treat congenital adrenal hyperplasia?
Ambiguous genitalia
You should repeat the 17 hydroxyprogesterone test
Hydrocortisone and fludrocortisone just like in primary Adriel insufficiency
What is the mnemonic for remembering the three layers of the adrenal gland
Which hormones are made in each level
GFR, the deeper you go the sweeter it is
Glomerulosa, aldosterone
Fasciculata’s cortisol and glucocorticoids
Reticularis sex steroids
If a patient on the boards looks like congenital adrenal hyperplasia but also has hypertension, what is likely the enzyme deficiency?
Why is there hypertension, describe the sodium levels
11 hydroxylase deficiency
Because this is a non-salt wasting form of CAH, sodium levels are normal
If a patient looks like congenital adrenal hyperplasia but also has hypertension and hypo kalemia with or without metabolic alkalosis, what is the enzyme deficiency
Describe a micropenis
What are four causes of this?
17 hydroxylase deficiency
Penis that looks normal but it’s less than 2 cm in outstretched length with present testes in the scrotum
Growth hormone deficiency, Prader Willi, Kallman syndrome, Panhypopituitarism
How is androgen and sensitivity syndrome inherited?
What is the physiology that causes this?
What anatomy will be described
X-linked recessive
Receptors for androgens are insensitive to androgens so no mail external Genitalia develop even though testes are present
Look for blind ending vagina, lack of uterus, lack of ovaries, testes may be in the inguinal canal, also think of this in primary amenorrhea with a “female quote with breasts but no pubic hair
If the exam mentions a family history of maternal aunts who are sterile these aunts likely had what disorder
Why do males with androgen and sensitivity syndrome have no internal female structures?
Androgen insensitivity syndrome, they are XY feminized males
Because they still have malarian and inhibiting hormoneWhich causes regression of the internal structures and only develop the external female structures due to the insensitivity to androgens
Describe androgen insensitivity with respect to breasts, pubic hair, Menstruation
Describe how a child will look with mullerian inhibitor Hormone deficiency
What will be their karyotype
Press will be present due to the fact that estrogen receptors do work, no pubic hair and no menstruation due to no internal female structures
They will have normal testes and penis because androgens work but they will also have a rudimentary uterus and fallopian tube because they did not regress
XY
Which heart defect are associated with turner syndrome
What other physical findings can be present
Why does primary amenorrhea occur
What Renal anomaly is associated with this
Bicuspid aortic valve which is most common and coarctation
Webbed neck only breast buds but no breasts, short stature, pedal edema, wide space nipples, short fourth and fifth metacarpal’s with scant or no pubic hair
Because the ovaries our streak ovaries which lead to ovarian failure
Horseshoe kidney
What are the top two reasons for ovarian failure?
If giving a bolus of dextrose to an infant or a young child what is the dose given? What is the max dose
Turner syndrome and autoimmune ovarian failure
2 mL per kilogram of D10, maximum dose is 500 mL which would be 50 g of dextrose
Diagnosed type two diabetes you need to have at least two abnormal tests, what are four possible tests?
What will C-peptide levels be like in type one diabetes? And type two diabetes?
Hemoglobin A1c greater than 6.5%
Random plasma glucose greater than 200
Fasting glucose greater than 126
Two hour oral glucose tolerance test greater than 200
C-peptide will be low in type one and high in type two
What are five findings associated with metabolic syndrome
Truncal obesity, low HDL, high triglycerides, high blood pressure with or without fasting blood glucose greater than 100
