Week 1 Block 1: EGR

Question 0

Locating on CT: Esophagus

Answer 0

Between trachea and vertebral bodies in superior thorax. usually collapsed with no visible lumen in CT images of chest

Question 1

(1) Dx: amenorrhea, restricted diet, regular exercise, distorted body image, dry skin, fine hair (2) Hormone levels: LH, FSH, Estradiol

Answer 1

(1) Anorexia nervosa (2) All decreased (hypogonadotropic amenorrhea, since body fat abnormally low, leading to loss of normal cyclic LH surge)

Question 2

Hirschsprung disease: (1) Mechanism (2) Body part(s) always involved

Answer 2

(1) Abnormal migration of neural crest cells during embryogenesis. These cells are precursors of ganglion cells of intestinal wall plexi. (2) Since neural cells migrate caudally, rectum is always affected

Question 3

(1) Most acid labile Picornavirus (2) It’s colonization limitations

Answer 3

(1) Rhinoviruses are acid labile and (2) therefore cannot colonize GI tract or cause gastroenteritis (unlike other picornaviruses, which are enteroviruses and relatively acid stable)

Question 4

(1) Embryological defect: sublingual mass removed, then lethargy, feeding problems, constipation, and dry skin (2) Clinical advisory note (3) Dx & other Sx

Answer 4

(1) Failure of migration of the thyroid gland can cause lingual thyroid (2) Surgeons should be careful when removing any mass along the thyroglossal duct’s usual path, as the mass could be only thyroid tissue present (3) Hypothyroidism: Macroglossia, umbilical hernia, large fontanels, hypothermia, jaundice

Question 5

(1) Dx: low serum sodium, initial low urine osmolality, urine osmolality after dehydration > 500 mOsm/L (2) Tx

Answer 5

(1) Primary polydipsia (2) Water restriction

Question 6

(1) Dx: upper GI bleed, mucosal tear at GE junction, alcoholic (2) Acid base disturbance

Answer 6

(1) Mallory Weiss tear (result of repetitive, forceful vomiting) (2) can lead to metaabolic alkalosis

Question 7

Use of beta blockers in thyrotoxicosis: (1) their 2 mechanisms (2) third mechanism of thyrotoxicosis tx not addressed by beta blockers & tx used instead

Answer 7

(1) Decrease in effect of sympathetic adrenergic impulses reaching target organs & Decrease in rate of peripheral conversion of T4 to T3 (2) thyroid hormone synthesis and release (use pharmacologic doses of iodine)

Question 8

Diabetes drug activating PPAR gamma (peroxisome proliferator activated receptor gamma): (1) Drug Name (2) Effect

Answer 8

(1) Thiazolidinediones (TZDs) (2) Activate PPAR gamma, which is nuclear receptor that alters transcription of genes responsible for glucose and lipid metabolism… TZDs exert glucose lowering effects by decreasing insulin resistance (partially by increased expression of adiponectin gene)

Question 9

C peptide and diabetes mellitus: (1) Marker of what process & in what context (2) Drug that increases c peptide levels

Answer 9

(1) Marker of total rate of endogenous beta cell insulin secretion under steady state conditions (2) Sulfonylureas (e.g., glyburide) increase rate of insulin secretion and C peptide levels in patients with type 2 diabetes

Question 10

Sporadic colon cancer: 3 stages & genes involved

Answer 10

(1) Progression from normal mucosa to small polyp: APC tumor suppressor gene (2) Increase in size of polyps: K ras proto oncogene mutation facilitates growth of adenomas by causing uncontrolled cell proliferation (Note: size of adenomatos polyps determines malignant potential. Adenomas < 1 cm are unlikely to undergo malignant transformation, while those > 4cm are very likely (40 percent) to progress to adenocarcinoma) (3) Malignant transformation of adenoma to carcinoma: p53 and DCC

Question 11

Diabetes Insipidus: (1) Intervention distinguishing central versus nephrogenic (2) Damaged areas causing transient central DI vs. permanent central DI

Answer 11

(1) ADH administration: increases urine osmolality in patients with central DI & no change in urine osmolality in patients with nephrogenic DI (2) Damage to posterior pituitary gland produces only transient central DI. Permanent central DI usually results from damage to hypothalamic nuclei or pituitary stalk.

Question 12

Ribavirin: (1) Clinical use (2) Mechanisms

Answer 12

(1) Chronic hepatitis C along with interferon alpha (also RSV) (2) Multifactorial: induce lethal hypermutation, inhibit RNA polymerase and inosine monophosphate dehydrogenase (depleting GTP), cause defective 5’-cap formation on viral mRNA transcripts, & modulate more effective immune responses

Question 13

Systemic mastocytosis: (1) Increased substance (2) GI finding

Answer 13

(1) Mast cells & histamine secretion (2) Gastric hypersecretion

Question 14

DDx: insidious onset of nonbloody diarrhea, fever, malaise, and perianal fistulae

Answer 14

Crohn’s disease (form of IB may involve any portion of GI tract from mouth to anus)

Question 15

(1) Dx: 30 yr old woman, diarrhea & weight loss for several months, diffuse bone pain and weaknesss, vitamin abnormality & normal magnesium levels, diarrhea improves with adherence to gluten free diet (2) Vitamin abnormality & initial lab evals for Serum Ca, Phosphorus, and PTH

Answer 15

(1) Celiac disease (2) Vitamin D deficiency (via malabsorption): decreased serum phosphorus, increased PTH (secondary hyperthyroidism), & low serum calcium

Question 16

Cause of neonate hypoglycemia: mother tx with insulin after being dx with gestational diabetes, hx of depression and drug abuses but denies using for past few years, 9 lb fifteen oz

Answer 16

High blood glucose levels in maternal circulation cross placenta causing fetal hyperglycemia and islet cell hyperplasia. (Also note: hyperinsulinemia caused by islet cell hyperplasia is thought to cause fetal macrosomnia.)

Question 17

(1) Dx: 23 yo caucasian male, bilateral breast enlargement, tall stature, little body hair, testicles small and firm (2) Significant lab finding

Answer 17

(1) Klinefelter (XXY) (2) Increased plasma FSH reflects gonadal failure in patients with Klinefelter syndrome. The estrogen: testosterone ratio determines extent of feminization.

Question 18

Hydrochlorothiazide: effects on blood levels of certain substances

Answer 18

Causes hypercalcemia by increasing distal tubular reabsorption of filtered calcium. Increased calcium levels usually suppresses PTH.