Labs

Question 1

Prolactin level

Answer 1

• AM fasting collection
• Increased in prolactinoma, hypothyroid, estrogen, anti-psych meds
• Normally zero unless preg.

Question 2

Cortisol

Answer 2

• Sleep dependent, raised by stress
• Increased in cushing
• Decreased in adrenal insufficiency, ACTH insufficiency
• Use ACTH stimulation to determine cause of deficiency

Question 3

Follicle stimulating hormone

Answer 3

• Work up of infertility- LH a better measure

- Stimulates sex hormone synthesis

Question 4

Luteinizing hormone

Answer 4

• Stimulates sex hormone production
• Hypogonadism: amenorrhea, decreased libido, impotence
• Distinguish testosterone deficiency or pituitary

Question 5

Dexamethasone suppression test

Answer 5

• Cushing syndrome
• Admin at 11 PM, check cortisol at 8 am
• Cushing = high cortisol due to inability to suppress negative feedback of HPA axis

Question 6

Growth hormone

Answer 6

• Pulsatile through out day

- Measure IGF-1 instead

Question 7

Aldosterone

Answer 7

• Discontinue anti-HTN and diuretics 2 wks prior
• Increased in secondary hyperaldosteronism
• Decreased in adrenal insufficiency, panhypopituitaryism

Question 8

Vasopressin challenge test

Answer 8

• Distinguish diabetes insipidus
• Give ADH, measure urine volume 12 H before & 12 H after
• Pts with DI have marked reduction in thirst, polyuria

Question 9

Water deprivation test

Answer 9

• Distinguish DI from primary polydipsia
• Deprivation of fluid intake, measure urine osmolality
• Give vasopressin
• DI will have decreased urine output

Question 10

Fasting blood sugar

Answer 10

• Best indicator of glucose homeostasis

- >126 on 2+ occasions is diagnostic

Question 11

Random blood sugar

Answer 11

• Check at anytime

- >200 is diagnostic

Question 12

HgA1c

Answer 12

• 5.7% - 6.4% pre-DM
• > 6.5% DM
• Indicated glucose over 2-3 months
• Indicate compliance to tx
• Repeat every 3-6 months for DM

Question 13

• 2-hr postprandial glucose

Answer 13

• Bodies response to sugar
• Should return to normal level in normal pt
• > 200 in DM

Question 14

Oral glucose tolerance test

Answer 14

• Gestational DM
• Sx of DM without abnormal FBS
• Sugars measure before and after glucose load
• Should not exceed 200

Question 15

Serum fructosamine

Answer 15

• Measures glycoselated proteins in serum
• Correlated with glucose control over 2-3 weeks based on album
• Detects poor glycemic control
• > 285