Endocrinology Board Review

Name: Endocrinology Board Review
Uploaded: 2017-06-27T20:27:25+00:00
Duration: PTM33S51
Channel: Jane Ackerly
Description: Endocrinology Board Review

Endocrinology Board Review
September 24, 2010

Growth

Growth After 18mos of age, growth curve should be followed closely
Between 4y/o and adolescence, growth below 4- 5cm/yr should be assessed Percentiles should not be crossed Pubertal growth spurt Girls  early puberty Boys  midpuberty Very rapid growth in the first year of life

Growth Rate per Year Age Inches Centimeters Birth to 1 year 7 to 10
1 to 2 years 4 to 5 10 to 13 2 years to puberty 2 to 2.5 5 to 6 Pubertal growth spurt-girls 2.5 to 4.5 6 to 11 Pubertal growth spurt-boys 3 to 5 7 to 13

Question 1 Choose the correct statement comparing “familial or genetically determined short stature” and “constitutional delay of growth,” in regards to bone age. A. Familial = delayed/ constitutional = advanced B. Familial = equivalent/ constitutional = delayed C. Familial = delayed/ constitutional = equivalent D. Both are delayed Answer: B

Constitutional delay of growth
Variant of normal growth and pubertal development Period of decreased linear growth within first 3yrs of life Downward crossing of percentiles Linear growth resumes at normal rate Along lower growth percentiles Family history of “Late Bloomers”

Constitutional Growth Delay:
Note deceleration followed by normal growth rate

Question 2 The physical findings depicted below corresponds to which tanner stage? A. I B. II C. III D. IV E. V Answer: D Stage IV-The hair distribution is now adult in type but still considerably less than that seen in adults. There is no spread to the medial surface of the thighs. No inverse triangle. (Key tip off to answer) Stage IV-The areolae and papillae elevate above the level of the breasts and form secondary mounds with further development of the overall breast tissue.

Tanner Staging Boys: Staged by genital development and pubic hair – starts at 9-14 Testis volume >= 4mL is pubertal Mark of pubertal onset Girls: Staged by breast development and pubic hair – starts at 10 ½ Stage II = breast buds Stage IV = Areola elevated above breast (secondary mound) Just need to memorize these

Hypothalamus and Pituitary

Hypothalamus Neuroectodermal tissue Inferior third ventricle
Pituitary stalk Pituitary stalk provides a means for hypothalamic factors to reach the pituitary

Pituitary Anterior Posterior
Upgrowth of ectodermal cells from Rathke’s pouch Posterior Downgrowth of neural tissue cells from the hypothalamus

Question 3 You are evaluating a patient in clinic and notice the abnormality pictured. Which of the following is most likely to be affected? A. Growth hormone levels B. Aldosterone levels C. Catecholamine levels D. Insulin levels Answer: A, midline defect, can affect any of the pituitary hormones

Anterior Pituitary Growth Hormone Secretion Inhibition IGF-1, IGF-BP3
GH-releasing factor Inhibition Somatostatin IGF-1, IGF-BP3 IGF1 – Insulin-like growth factor I, IGF-BP3 – insulin-like growth factor binding protein

Anterior Pituitary Growth Hormone Deficiency Normal birth weight
Normal growth pattern x 1 year “Kewpie” doll appearance, “cherubic” Short, excess subq fat, retarded body proportion changes and high-pitched voices Diagnosed with stimulation test

Anterior Pituitary ACTH Secretion Inhibition CRF from hypothalamus
Cortisol from adrenals Prolonged steroid use Corticotropin Releasing Hormone

Anterior Pituitary Gonadotropins Secretion Inhibition FSH LH GnRH
Hypothalamus sends pulses Increases during puberty Inhibition Inhibin FSH Aromatase (androgen to estrogen) Spermatogenesis LH Testosterone Androstenedione (estradiol) GnRH – Gonadotropin releasing hormone

Anterior Pituitary TSH Secretion Inhibition Actions TRH
Thyroid Hormone Actions Increases iodide uptake, thyroglobulin synthesis and thyroid hormone Thyrotropin Releasing Hormone

Anterior Pituitary Prolactin Acts directly on target organ
Initiation and maintenance of lactation Inhibited by dopamine from hypothalamus Hyperprolactinemia Galactorrhea Pituitary adenomas Medication Neuroleptics, antipsychotics, estrogens and anti-hypertensives

Question 4 You are on call in the PICU and following a very sick patient admitted with meningococcal meningitis. He has not had any urine output in the last 8 hours despite fluid administration. You order a BMP and his Na is What is the most likely cause of the hyponatremia in this patient? A. Diabetes insipidus B. Psychogenic polydipsia C. Inappropriate fluid administration D. SIADH Answer: D. Patients with any injury that can affect the head can have pituitary problems

Posterior Pituitary Hormones synthesized in hypothalamus and stored in posterior pituitary Vasopressin AVP or ADH Released in response to increased osmotic pressure in the blood Water balance Increased reabsorption of water in collecting ducts of kidneys Arteriolar vasoconstriction – HTN Increased thirst Arginine vasopressin or anti diuretic hormone

Posterior Pituitary Vasopressin Overproduction Underproduction
Head trauma, brain tumors, encephalitis, pneumonia SIADH HA, apathy, nausea, vomiting, impaired consciousness Decreased plasma osmolarity Underproduction Central Diabetes Insipidus (DI) Pituitary tumors, head trauma, infiltrative diseases, autoimmune or surgical Increased plasma osmolarity

Posterior Pituitary Vasopressin Oxytocin Resistant
Nephrogenic DI Tubules in kidney cannot respond Genetic or acquired (lithium) Oxytocin Released in response to nerve stimulation Contraction of the smooth muscle of the uterus and myoepithelial cells lining the ducts of mammary glands

Thyroid

Thyroid Location Hormones Neck Base of tongue Mediastinum
Thyroxine (T4) Tri-iodothyronine (T3) Need iodine for synthesis Transported by TBG, albumin and transthyretin Free hormone is active Thyroid tissue migrates inutero from the base of the tongue, so can appear anywhere TBG – thyroid binding globulin. Free hormone, important to check free t4 levels

Thyroid Goiter Nodules Hyper or hypo 70-80% benign or cystic
1-1.5% of all childhood cancers Neck irradiation, family history of medullary carcinoma, rapid growth, fixation to adjacent structures, enlarged lymph nodes

Question 5 A mother brings in her teenage daughter for hyperactivity and emotional lability. ROS is positive for diarrhea, weight loss and heat intolerance. On physical exam you notice tachycardia and a slight prominence of the eyes. A laboratory evaluation would most likely reveal: A. TSH, freeT4, + TSH receptor antibodies B. TSH, free T4, + antithyroperoxidase antibodies C. TSH, free T4, + TSH receptor antibodies D. TSH, free T4, + antithyroperoxidase antibodies Answer: C. We are thinking the symptoms are from hyperthyroidism which would have increased fT4 and decreased TSH, Prominence of eyes gives the hint that it may be Graves which would be stimulating antibodies to the TSH receptor

Thyroid Hyperthyroid Soft and fleshy gland Tachycardia Weight loss
Increased frequency of bowel movements Heat intolerance Nervousness Widened pulse pressure Tremor Fatigue Warm, moist skin Fine, friable hair Separation of distal margin of nail bed Restlessness Inability to sit still Emotional lability Short attention span Excessive sweating

Thyroid Hyperthyroidism Graves Disease Large gland Bruit Labs
Stimulating antibody to TSH receptor Exopthalmos Proptosis and lid lag Large gland Warm on palpation Bruit Labs Increased T3 and T4 Decreased TSH Treatment – bblockers, methimazole, surgery, radiation

Thyroid Congenital Hypothyroidism 1 in 4000 Cretinism
Broad nasal bridge Coarse facial features Mental retardation Short stature Puffy hands Protuberant tongue Delayed skeletal maturation Treatment within 3-4 weeks Newborn Screening

Thyroid Hypothyroid Hypothalamic abnormalities Pituitary abnormalities
Iodine deficiency Chronic lymphocytic thyroiditis Hashimoto thyroiditis Anti-thyroid antibodies Thyroglobulin Thyroperoxidase Positive FH Increased TSH, decreased T4 Hypothalamus secretes TRH Pituitary secretes TSH Don’t forget that you can get a transient hyperthyroid with any thyroiditis initially

Thyroid Hypothyroid symptoms Firm or bosselated gland
Congenital vs Acquired Dry skin Constipation Hair loss Fatigue Cold intolerance Apathy Depressed or delayed relaxation Treat with thyroid hormones

Aquired hypothyroidism most frequently due to Hashimoto/chronic lymphocytic thyroiditis.
Acquired hypothyroidism: Note the sharp deceleration in growth before the onset of symptoms. Following initiation of therapy significant catch-up growth is seen.

Calcium and Phos Metabolism

PTH Bone: Intestine: Kidney: Increases release of Ca and Phos
Increased re-absorption of Ca and Phos Kidney: Increases excretion of Phos Decreases excretion of Ca Stimulates Synthesis of Vit D3

Effects of PTH Bone Intestine Kidney Net Effect Ca Phos

Vitamin D Bone Intestine Kidney Increases release of Ca
Increases release Ph Intestine Increases absorption of Ca Increases absorption of Ph Kidney Improves reabsorption of Ca Increases reabsorption of Ph Remember PTH stimulates Vit D to be made

Vitamin D Bone Intestine Kidney Net Effect Ca Phos

Calcitonin Bone Intestine (no specific effects) Kidney
Inhibits reabsorption of Ca Inhibits reabsorption of Ph Intestine (no specific effects) Kidney Decreases reabsorption of Ca Decreases reabsorption of Ph The counterregulatory hormone of PTH

Net Effect of 3 Hormones Ca Phos Vit D PTH Calcitonin

Hyperparathyroidism Results in hypercalcemia
Manifestation of multiple endocrine neoplasia I (MEN 1) Autosomal dominant Islet cell tumors Zollinger-Ellison syndrome Pituitary tumors

Hypocalcemia Symptoms: Paresthesias Irritability Muscle Cramps Tetany
Seizures

Question 6 A two day old infant experiences a prolonged seizure with respiratory arrest requiring intubation. BMP reveals hypocalcemia, and CXR demonstrates absent thymic shadow. Genetic testing is likely to reveal: A. Trisomy 21 B. Trisomy 18 C. Deletion of 22q11.2 D. Deletion of 15q13.3 E. DF508 Mutation Answer: C. DiGeorge

Hypoparathyroidism Idiopathic (Autoimmune) DiGeorge Syndrome Ca low
Dysmorphic features Cardiac defects Immune deficiency Thymic aplasia Low PTH Deletion of 22q11.2 May present with seizures secondary to hypocalcemia Ca low P high PTH low For cardiac, conotruncal defects most common Interrupted aortic arch Tetralogy of Fallot Truncus arteriosus Atrial or ventricular septal defects Vascular rings

Pseudohypoparathyroidism
PTH is elevated Unresponsiveness to PTH (Bone/Kidney/Both) Albright hereditary osteodystrophy Suspect in short child with hypocalcemia Ca low P high PTH high

Albright hereditary osteodystrophy
round facies, short stature, and obesity, as seen in these three sisters. B, A short fourth metacarpal may be easily appreciated in this photograph.

Vitamin D-Deficient Rickets
Vitamin D deficiency may result from Inadequate sunlight exposure Malabsorption Drugs that affect Vit D Phenytoin, phenobarb Signs/Symptoms Poor linear growth Delayed walking Muscle weakness Bone pain Hypotonia Anorexia Ca NL/low P low PTH high AlkP high

Vitamin D-Deficient Rickets
Genu Varum and metaphyseal flaring. Bowing of long bones Rachitic Rosary (prominence of costochondral junction) Harrison’s groove: Indentation of lower anterior thoracic wall Frontal bossing

Others Vitamin D-Resistant Rickets Pseudovitamin D-Deficiency Rickets
Resistance to Vit D, even when high amounts used Findings in first months of life Pseudovitamin D-Deficiency Rickets AKA 1a-hydroxylase deficiency or Vit-D dependent rickets type I Findings appear in early infancy Autosomal recessive

Adrenals

Adrenal Gland Cortex Medulla Glucocorticoids Mineralocorticoids
Androgens Medulla Epinephrine Norepinephrine

Adrenal Glands Cushing Excessive glucocorticoids
Endogenous or exogenous steroid exposure Causes Adrenal tumors Pituitary adenomas (Cushing disease) Ectopic ACTH production

Adrenal Gland Features of Cushings Rounded facies Plethora
Central obesity Impaired linear growth Fatigue Hypertension Buffalo hump Muscle weakness and muscle wasting Skin is thin and easily bruised Osteopenia/osteoporosis

Adrenal Gland Cushings Labs
Elevated 24-hour urine free cortisol excretion Elevated salivary cortisol Delineating the cause High- and low-dose dexamethasone suppression tests No diurnal variation

Adrenal Gland Addison’s Disease Insufficiency Causes Glucocorticoid
Mineralocorticoid Causes Autoimmune destruction Tuberculosis Autoimmune polyendocrine syndromes Adrenoleukodystrophy, Wolman disease, hereditary unresponsiveness to ACTH, Allgrove syndrome, and congenital adrenal hypoplasia Massive adrenal hemorrhage can occur with meningitis or traumatic births

Adrenal Gland Addison’s Weight loss Wasting of subcutaneous tissue
Hyperpigmentation Weak Confused Decreased circulating plasma volume Hyperpigmentation - due to co-secretion of ACTH and MSH (melanocyte-stimulating hormone), hyperpigmentation is striking and appears as bronzing of the skin, more obvious in flexor creases, in scars, and over the areolae of the nipples Decreased volume on CXR with small heart

Adrenal Gland Addison Labs Less pronounced disease in ACTH deficiency
Hyponatremia Hyperkalemia Less pronounced disease in ACTH deficiency If untreated Weaken Vascular collapse Labs due to loss of mineralocorticoid activity, need to replace cortisol and mineralocorticoids Aldosterone is controlled mainly by renin-angiotensin system

Question 7 A 3-week-old female infant is brought to the ER for vomiting, decreased oral intake and lethargy of 3 days’ duration. Because the infant had not regained her birthweight at the 2-week visit, the mother was instructed to wake her every 2 hours to breastfeed. On PE, the infant’s temp is 98.6F, HR 190, BP 60/30. She appears thin and lethargic and has a poor suck. Her anterior fontanelle and eyes appear sunken, and her CR is 3 secs. You note an enlarged clitoris and partial labial fusion. Assessment of serum electrolytes in this infant is MOST likely to reveal A. Hyperchloremia B. Hyperglycemia C. Hypernatremia D. Hypokalemia E. Hyponatremia Answer E

Adrenal Gland CAH Autosomal recessive Symptoms reflect specific defect
21-hydroxylase deficiency Most common Decreased glucocorticoid Hypoglycemia Decreased mineralocorticoid (severe forms) Salt-wasting Hyperkalemia/hyponatremia Elevated 17-hydroxyprogesterone Excess androgens Masculinization Shock and death if untreated

Deficiency in 21-hydroxylase activity (CYP21) prevents the conversion of 17-hydroxyprogesterone to 11-deoxycortisol, resulting in an elevation of 17-hydroxyprogesterone and shunting of precursors into the pathway for androgen biosynthesis

Adrenal Gland Other forms of CAH Less severe 21-hydroxylase deficiency
May present later Premature pubarche, rapid growth, skeletal maturation 11β-hydroxylase 17α-hydroxylase Delayed puberty Undervirilization of males

Adrenal Gland - Medulla
Pheochromocytoma Rare Catecholamine-secreting tumor Norepinephrine, Epinephrine, Dopamine (rarely) Symptoms HA, diaphoresis, palpitaions, tremor, nausea, weakness, anxiety, weight loss Hypertension (episodic), AMS, arrhythmia Syndromes MEN 2A, 2B, NF, VHL Diagnosis Plasma metanephrines, 24-hour urine catecholamines and metanephrine

Sexual Differentiation

SRY gene Short arm of Y chromosome Promotes differentiation of Sertoli cells Mutations lead to male to female sex reversal Ambiguous genitalia “the baby” Endocrine, urology, psychologist or social worker Palpate for gonads Symmetrical but no gonads suggests virilized female, palpable gonads suggests incomplete male development

Ambiguous Genitalia CAH No palpable gonads 17-hydroxyprogesterone Leydig cell hypoplasia, inborn errors of testosterone synthesis, androgen insensitivity Palpable gonads LH, FSH, testosterone, dihydrotestosterone Complete androgen insensitivity Externally female Uterus absent Labial or inguinal gonads A. True hermaphrodite; B-E. CAH

Persistent mullerian duct syndrome Persistance of structures in normal 46,XY male Cryptorchidism or testicular ectopia Defect in anti-mullerian hormone Agenesis of the phallus Developmental

Question 8 You are examining a 2-week-old male infant for the first time and note an undescended right testicle. His mother asks when is the optimal time to correct this problem. The MOST appropriate time at which to recommend surgical repair for this infant if spontaneous descent has not occurred is A. 4 months B. 12 months C. 24 months D. 36 months E. 48 months Answer B.

Cryptorchidism Migration Kidneys to scrotum 3% of male infants
Treatment 6-12 months Orchiopexy Increased risk for malignancy Surgical intervention does not alter risk

Precocious Puberty

Precocious Puberty Girls Boys Central <8 <9
Gonadotropin-dependent Activation of HPG axis FSH, LH Hypothalamic hamartomas Gelastic seizures Intracranial neoplasms 8 is breast development for girls, testicular enlargement for boys

Precocious Puberty Gonadotropin- independent
Increased gonadal steroids No HPG axis involvement McCune-Albright syndrome Café-au-lait Polyostotic fibrous dysplasia Precocious puberty Gonadal or adrenal neoplasms Rare Familial male-limited precocious puberty

Question 9 During the hospital discharge examination of a term female neonate, you palpate a 1-cm mass beneath her right nipple. There is no erythema at the site and no discharge from either nipple. The mass is nontender and freely mobile. The genitalia appear mildly swollen but are otherwise normal. Of the following, the MOST appropriate treatment is A. Excisional biopsy B. Fine-needle aspiration of the mass C. IM gonadotropin-releasing hormone D. Oral cephalexin E. Reassurance of the parents Answer: E

Premature Thelarche Breast tissue development Diagnosis of exclusion
Uni or bilateral May regress or persist Diagnosis of exclusion No other signs of pubertal development Exogenous estrogen 1-2y Self-limited Normal in neonates Exogenous estrogen - OCPs

Premature Pubarche Pubic hair <8y in girls; <9.5y boys
Axillary hair, body odor, acne Due to Premature adrenal pubertal maturation PCOS Late onset CAH Tumor - rare Prep question, hair development in male but not testicular enlargement

Delayed Puberty

Delayed Puberty Constitutional Delay Central Gonadal Normal variant
Kallmann Syndrome Hypothalamic hypogonadism Acquired Trauma, neoplasm, infiltrative disorders, hyperprolactinemia, chronic illness - anorexia, CF, sickle cell Gonadal Turner, Klinefelter Trauma, chemotherapy, radiation

Delayed Puberty Other Androgen insensitivity 17-hydroxylase deficiency
Inguinal or labial mass Primary amenorrhea 17-hydroxylase deficiency Cannot produce sex steroids

Turner Syndrome XO Short stature Gonadal failure Other Mosaic
Streak ovaries Other Cubitus valgus, shieldlike chest, webbed neck Cardiac Renal Mosaic Mosaics may have no symptoms

Klinefelter Syndrome 47, XXY Small, firm testes Gynecomastia
Neurobehavioral difficulties

Diabetes You will get more diabetes than you ever dream of on Purple team!

Hypoglycemia

Hypoglycemia Signs and symptoms Fasting vs. Stress vs. Iatrogenic
ANS, Epinephrine, CNS glucopenia Fasting vs. Stress vs. Iatrogenic Hyperinsulinism Most common cause in neonates Mutations of enzymes, iatrogenic, adenoma Beckwith-Wiedemann Macrosomia, macroglossia, omphalocele, hemihypertrophy and embryonal tumor

Hypoglycemia Ketotic hypoglycemia Other
Common cause of childhood hypoglycemia 18 months to 5 years Resolves by 8 to 9 years Other Hypopituitarism, GSD, disorders of gluconeogenesis

Obesity

Question 10 You care for a 17-year-old boy who is overweight. He has gained 44 lb (20 kg) in the last year, especially in his abdominal area. On examination today, his blood pressure is 158/90 mm Hg using a large, appropriately sized cuff. His mother has a similar body habitus and is being treated for type 2 DM. Of the following, the MOST likely abnormalities to expect in this patient if his presentation continues into adulthood is A. High triglycerides and low HDL B. Hypoglycemia from insulin sensitivity C. Low concentrations of C-reactive protein in the blood D. Low fibrinogen concentration with bleeding diatheses E. Low triglycerides and low LDL Answer A.

Obesity Look for causes of secondary obesity Metabolic Syndrome
Endocrine Genetic CNS Metabolic Syndrome Obesity Insulin resistance Dyslipidemia HTN Increased risk of developing Type 2 DM and CV disease Look for PCOS Hyperandrogenism, irregular menses, chronic anovulation Most common cause is exogenous obesity

Endocrinology Board Review

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