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154 Cards in this Set

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Types of measurements:
-direct mesasurements
-24 hours urine measurement
-stimulation test
-suppression test
Direct measurement
most hormones are found in low concntration in the serum and levels fluctuate based on stimuli and feedback mechanisms
24 hour measurement
measures metabolites of hormones and gives information on overall level of activity
Stimulation tests
assesses amounts of stored hormones
Suppression tests
Determines whether hyperfunctioning gland is controlled by feedback mechanism (determines if the gland responds to feedback mechanism of not)
Normally, when you supress - you should see levels of the hormone decline
Anterior pituitary hormones
-Growth hormone (hGH)(somatotropin)
-prolactin
-thyrotropin (thyroid stimulating hormone)
-Adrenocorticotropic hormone (ACTH)
-Follicle stimulating hormone (FSH)
-Lutenizing hormone (LH)
POsterior pituitary hormones
-Vasopressin (ADH)
-oxytoxin
Hypopituitarism
decreased function of the anterior pituitary
Causes of hypopituitarism
-mass lesions (brain tumore, aneurysms)
-trauma
-radiation
-surgery
-CVA
-congential deficeincies
Hypopituitarism may result in...
-gonadotropin defieciency (FSH and LH defeciency)
-TSH deficiency
-hGH deficiency
-ACTH deficiency
-pan-hypopituitarism (complete loss of all hormones)
Gonadotropin deficiency:
-loss of LSH and LH
-causes hypogonadism and infertility
TSH deficiency:
-cuases hypothyroidism
-fatigue, weakness, weight changes, hyperlipidemia, thinned heair
hGH deficiency:
-in adulthood: obesity, asthenia, low CO

-in childhood: delayed growth and development
ACTH deficiency:
-causes diminished cortisol secretion
-weakness, fatigue, weight loss
In addition to specific hormone deficiencies, other lab findings for hypopituitarism may include:
-low FBS
-hyponatremia
-normal potassium (aldosterone noraml)
-low T4 with low TSH (normally low T4 should be accompanied by high TSH)
-low-low/normal plasma levels of sex steroids (testosterone and estradiol)
Human Growth Hormone
-important in growth process of children and in metabolic functions in adults
-secreted by antior pituitary in reseponse to exercise, deep sleep, hypoglycemia, glucagon, insulin, or vasopressin
What causes the release of human growth hormone?
exercise, deep sleep, hypoglycemia, glucagon, insulin, or vasopressin causes its release from the anterior pituitary
What does hGH confirm?
hypopituitarism or hyperpituitarism
hGH normal values
<5 ng/ml
normal hGH stimulating and suppresions test:
stimulating: >5 ng/ml
use arginine, glucagon, or insulin to stimulate hypoglycemia - normally this should trigger secretion of GH.

supression: 0-2 ng/ml
Give glucose to induce hyperglycemia - noramlly, this should decrease GH
hGH deficiency:
-most common cause in children is idiopathic GH deficiency
-most common cause in adults is pituitary adenoma
hGH Excess:
-confirmed by failure of serum GH supression following oral glucose load

Causes:
-excercise or eating prior to test
-fasting/malnutrition
-liver disease
-renal failure
-uncontrolled diabetes
Supression test supporting hGH excess:
pts fasts for 12 hrs then tested for:
-prolactin (co-secreted in most GH secrting tumors)
-IGF-1 (increased up to 5x in most acromegalics)
-Glucose (DM common in acromegalics)
-LFTs
-BUN
-PO4 (frequently elevated)
-Free thyroxine and TSH
Supression test methodology supporing hGH excess:
-following 12 hr fast 100 GM glucose is administered
-measure GH 60 min after ingestion of glucose
-GH>2 ng/ml in males or >5 ng/ml in females indicated acromegaly
Prolactin: normal values
non pregnant female: 0-17 ng/ml
pregnancy female: 34-386 ng/ml
adult male: 0-15 ng/ml
Children: 3-20 ng/ml
Prolactin: critical values
>200 ng/ml in non-lactating adult indiacte a prolactin secreting tumor
Prolactin Test
-use 2-3 samples at different times to assess
-fasting samples are most appropriate
-serum is speciment of choice
Function of prolactin test:
-prolactin causes initiation and maintenance of lactation
Increased in prolactin are associated with:
-pregnancy
-nursing
-stress
-chronic renal silure
-cirrhosis
-hypothyroid
Decreased in prolactin are associated with:
-dopaminergic drugs inhibit production

true deficiency is RARE
Common reasons for testing prolactin:
Women:
-mentrual cycle disturbances (oligomenorrhea, amenorrhea)
-galactorrhea
-infertility

Men
-hypogonadism
-ED
-decreased libido
-inferitility
Vasopressin Normal values
0-4.7 pg/ml
What is the role of vasopressin?
-effects arterial smooth muscle and promotes water reabdoprtion from renal collecting ducts
-promotes Na and Cl reabsoption in loop of Henle
Excess ADH is associated with...
syndrome of inappropriae ADH secretion (SIADH)
What test should be done in the case of ADH excess?
water load test

Pts with ADH excess will excrete little/none of the water.
Urine will be very concentrated
ADH deficiency is associated with...
diabetes insipidus
What test should be done in the case of ADH deficeincy?
water restriction challenge

Water is restricted and osmolality of urine is measured before and after ADH is administered.
In neurogenic DI, ADH levels are low and osmalility doe not rise with water restriction but DOES rise with ADH admin.
In nephrogenic DI, ADH levels are high and osmalility does NOT rise with water restriction or with ADH admin.
Urine concentrating disorders include...
-diabetes insipidis
-psychogenic water intoxication
-SIADH
-syndromes of extopic ADH production (systemic neoplasms)
Thyroid function
Hypothalamus secretes TRH in reponse to decrease thyroid hormone (Decreased secretion of TRH is influenced by negative feedback from circulating thyroid hormones)
TRH causes pituitary to release TSH. TSH causes biosynthesis and release of thyroid hormones T3 adn T4. Thryoid takes up iodine and makes hormone
Hormone is released and bound to protein
Which thyroid hormone is responsible for turning the system off?
T3, and some T4
What are the binding characteristics of thyroid hormone?
99% is bound
thyroid binding globulin binds 80-85% of released thryoid hormones
pre-albumin binds 10-15%
albumin binds 5%

Only unbound T3 and T4 are metabolically active
How does liver disease effect thyroid?
In liver disease, the liver is not able to produce protein. Since so much of thyroid hormone is bound to protein, liver dysfunction will result in a decrease in thyroid hormones.
Kidney disease acts similarly bc kidenys dump lots of protein
Thyroid panel
-T3, T4 (total)
-Free T4
-TSH
-FTI (free thyroid index)
FTI
Free thyroid index

mathematical equations used to correct the estimated total T4 in relation to the amount of thyroid binding proteins present
Thyroid screen
Free T4
TSH

From these, we can tell where the problem is:
-If normal free T4 - thyroid is working
-If normal TSH - hypothalamus and pituitary are working
Thyroid disorders
-primary hyperthyroid
-graves dz
-plummers dz
Primary hyperthyroid
-T3, T4, FTI increased
-TSH decreased
Graves disease
diffuesely hyperactive thryoid
Plummers disease
hyperfunctioning thyroid nodule
Hyperthyroid Sx:
-exopthalmos (bug eyes)
-tachycarida
-heat intolerance
-tremor of fingers
-nervous appearance
-lid lag (lids are rasied, can see more of white of eye)
-warm moist skin
-weight loss
-diarrhea
Hyperthyroid realted labs:
-Hemoglobin normal
-WBC normal
-alkaline phosphatase may be elevated
What do you find in primary hypothyroid?
T3, T4 decreased
TSH increased
Signs and symptoms of primary hypothyroid?
-non-pitting edema of face, eyelids, extremeties
-loss of hair in anterior 1/3 of eyebrow
-large tongue
-cold dry skin
-depression
-lethargic appearance
-anorexia
-bradycardia
-constipation
Lab findings for primary hypothyroid?
-anemia in 50% of pts (macrocytic)
-increased CK
-increased AST
-cholesterol >250 mg/dl
Secreted thyroid hormones
-T4 (93%)and T3 (7%)
-99% of secreted hormones are protein bound and inactive
-thyroxine binding globulin, transthyretin (prealbumin) and albumin
-hormones are released at site of action and become active
HOw much of daily T3 comes from conversion from T4?
cellular conversion of T4 and T3 creates 80% of daily T3 needed
What can influence results of thyroid testing?
Increase
-estrogen therapy, pregnancy, heroin use

Decrease
-anabolic steroid use, androgen treatment, high dose salicylates
Primary Hypothyroid
Thyroid

inc TSH, dec T4
Secondary hypothyroid
pituitary

dec TSH, dec T4
Tertiary hypothyroid
Hypothalamus

dec TRH, dec TSH, dec T4
Thyroxine (T4)
-measured by EIA or RIA
-5% of circulating T4 is in free state (unbound), 95% bound
Why test for free T4?
-looks at metabolically active levels
-R/O hyper or hypo thryoid
-eval of thyroid replacement
-measure when protein abnormality is suspected
Why test for total T4 (bound and unbound)?
-good index of thyroid function when TBG is normal
-increased in TBG such as pregnancy will also increase total T4
Non thyroid illnesses that effect thyroid tests...
-cirrhosis/hepatitis
-renal failure
-severe infection
-trauma
-starvation
-post surgical testing
-cancer
-severe inflammation
-extensive burns
-accute psych illness
Total T4 increases with..
-hyperthyroid states
-acute throiditis
-TBG increases (pregnancy, hepatitis)
-graves dz
-Plummers dz
Total T4 decreases with...
-hypothyroid states
-pituitary insufficiency
-protein malnutrition
-iodine insufficiency
-renal failure
-cirrhosis
Newborn screen for hypothyroid...
-prevents mental retardation (hypothyroidism can cause brain not to develop)
-may also use TSH or combiniation measurement
Free T3 (triiodotyronine)...
-evaluates thyroid function
-used to confirm diagnosis of hyperthyroidism when minial rise in T4 is seen
-not usually helpful in evaluation of hypothyroidism (T3 is often normal in these patients)
-R/O T3 toxicosis (T4 normal, T3 high, TSH low)
-evaluates thyroid replacement
-decreased T3 seen in third trimester of pregnancy
-
TSH
-secreted from anterior pituitary
-stimulates release of thyroid hormone
-regulated by feedback inhibition
What does TSH test for?
-single most SENSTITIVE test for primary hypothyroidism
-will be elevated in primary HYPOthyroidism (obtain free T4 to confirm)
-can be high or low in euthyroid patient
-Evaluate replacement therapy
If there is clear evidence of hypothyroidism and TSH is not elevated, what should you consider?
consider hypopituitarism
TSH is increased in ....
-primary hypothyroidism (thyroid dysfunction)
TSH is decreased in....
-hyperthyroidism
-secondary hypothyroidism (pituitarism - pituitary dysfunction)
-pituitary hypofunction
Thyroxine Binding Globulin
-TBG is major protein carrier
-Used to evaluate pts with abnormal total T4 and T3 levels that do not correlate with clinical findings or other laboratory results
TBG is increased in ...
-pregnancy
-estrogen replacement
-hepatitis

when TBG is elevated, T3 and T4 (total) are also elevated.
TBG is decreased in...
-protein losing enteropathy or nephropathy
-malnutrition
-ovarian failure
-major stress
What tells you if the is thyroid working?
-iodine uptake
-T3
-T4
What tells you if there is protein to carry the hormone to the target organs?
-TBG (thyroid binding globulin)
What tells you if the thyroid is being told to work?
-TSH
-TRH
When should you order thyroid tests?
-obvious sx of hyperthyroidism
-obvious sx of hypothyroidism
-pt on thyroid replacement therapy
-part of normal physical exam
Obvious sx of hyperthyroidism?
-exopthlamos
-lid lag
-tachycardia
-weight loss without known cause
Obvious sx of hypothyroidism?
-hair loss
-bradycardia
-fatigue
-edema
-depression
-weight gain
Test women for thyroid is what 3 times?
-1st pregnancy
-menapause
-65 y/o
What does adrenal medulla do?
Produces vanillylmendeic acid (VMA)and catecholamines:
-epi
-NE
-metanepherine
-dopamine
-normatanepherine
What does adrenal cortex do?
zona glomerulosa (outer) - aldosterone

zona fasciculata (middle) - 17-hydroxycortisone aka cortisol

zona reticularis (inner) androgenic or estrogenic compounds
What is the main controller of the Adrenal Gland?
ACTH from the pituitary
VMA and catecholamine (adrenal medulla) tests are performed mainly to...
-dx HTN secondary to a tumor called pheochromocytoma (tumor produced epi so get sudden sympathetic sx)
-detect presence of neuroblastomas and other adrenal tumors
Excess OR defieciency of adrenal Cortex hormones may be d/t...
-Cushings
-addisons
-virilization syndrome
Aldosterone
-causes retention of sodium and loss of potassium
-production is regulated by the RAAS
Increased aldosterone in the presence of....
-low BP
-low sodium
-high ACTH
When should you test Cortisol levels?
-hyper and hypo functioning adrenal glands
CRG
-corticotropin releasing hormone
-stimulates production of ACTH in anterior pituitary gland
ACTH
-stimulates adrenal cortex to produce cortisol
What does Cortisol do?
-turns off CRH and ACTH

-potent glucocorticoid that effects metabolism of carbohydrates, proteins, and fats
-inhibits effect of insulin, therefore limits transport of glucose into cells (hyperglycemia)
-profound effect on serum glucose levels
Plasma cortisol levels provide the best method for evaluating....
adrenal activity
High cortisol levels are associated with...
-cushings disease

-cortisol is produced with no regard to feedback
-cortisol may be produced with ectropic ACTH producing tumors
low cortisol levels are associated with....
-Addisons disease (hypofunction of adrenal gland)
-Adrenal hypoplasia (hormones needed to make cortisol are absent)
-hypofunction of the pituitary gland
Cortisol levels rise and fall.....
during the day

-highest in AM
-lowest in evening (reversed in individuals who work nights)
Cortisol testing
-blood collected at 0800 and 1600 hrs

1600 value should be 1/2 to 1/3 the AM value
Dexamethasone Suppression Test is important for...
-dx of adrenal hyperfunction (Cushings syndrome) and its cause
Desamethasone Suppression Test Explanation:
-based on pituitary ACTH secretion and control
-corticotropin releasing hormone (CRH) is made in hypothalamus
-CRH stimulates production production of ACTH in anterior pituitary
-ACTH stimulates adrenal cortex to produce cortisol
-Cortisol turns off CRH and ACTH
Normally, as plasma cortisol increases....
ACTH decreases
Dexamthasone is a...
synthetic hormone similar to cortisol that will suppress ACTH
Providing body with dexamethasone causes...
decrease in production of ACTH and therefore a decrease in cortisol (50%)
In Cushings dz, what happens
in dexamethasone test?
feedback fails in 95% of pts
(95% of pts with cushings fail to suppress)
cortisol levels do not decrease
17-hydroxycorticosteroids (17-OCHS)
-metabolite of cortisol
-test measures breakdown products in urine to asses level of cortisone

17-hydroxycortisone is produced in zona fasciculata (middle) of the adrenal cortex
Elevated levels of 17-OCHS are associated with...
-adrenal hyperfunction whether the condition is caused by pituitary adrenal tumor, bilateral adrenal hyperplasia, or ectopic tumors producing ACTH
-hyperthyroidism
-Cushings
Decreased levels of 17-OCHS are associated with....
-Adrenal hypoplasia may be caused by hemorrhage, infarction, metastitic tumor, autimmune conditions, or surgical removal without appropriate hormone replacement
-hypopituitarism
-hypothyroidism
-Addisons
-adrenal suppresion after prolonged exogenous steroid ingestion
17-ketosteroids (17-KS)
-urine test performed to assist in eval of adrenal cortex function (particularly as it relates to androgenic function)
-eval and monitor adrenal hyperplasia (adrenogenital syndrome) and adrenal tumors
-metabolites of testerone and other sex hormones
Main 17-KS is...
DHEA (dehydroepiandrosterone)
In men, where does 17-KS come from?
-1/3 from testosterone
-2/3 from other androgenic hormones produced in the adrenal cortex
In women and children, where does 17-KS come from?
-non-testosterone hormones produced in adrenal cortex
17-KS test is good to diagnose...
Adrenal cortex malfunction
Do 17-KS levels reflect cortisol levles?
No
Increased 17-KS levels are associated with...
-congenital adrenal hyperplaisia (infants)
-androgenic tumors of adrenal tumors (older children/adults)

these cause virilization syndrome
Decreased 17-KS levels are associated with....
-stress (during stress, adrenal production shidts from 17-KS to cortisol)

decreased levels are of little significance
What are the 3 main adrenal tests?
1. 17 hydroxycorticosteroids (main one is hydroxycortisone)

2. 17 ketosteroids

3. cortisol
Hyperadrenalism
-Cushings syndrome
-adrenocortical hyperfunction

-excess production of glucocorticoids
-dexamethasone suppresion test will differentiate
Hypoadrenalism
-Addisons disease

-hypocortisolism
-low plasma cortisol at 8 am
2 forms of plasma Cortisol:
- bound (90%) - inactive

-unbound (10%) - active
What is the main cortisol binding protein?
transcortin
Increase is transcortin may be due to...
-increased estrogen
-pregnancy
-hyperthyroidism
Decrease is transcortin may be due to..
-increased androgens
-hypothyroidism
Three main reasons for cortisol testing..
-congential adrenal hyperplasia
-virilization syndrome
-cushings disease
Congential Adrenal Hyperplasia
-aka adrenogenital hyperplasia
-enzyme defect blocks chain of events leading to the production of cortisol
What three things occur in congenital adrenal hyperplasia?
-high level of androgens lead to development of secondary sex characteristics
-adrenal glands increase in size
-pathway leading to aldosterone is blocked and salt losing crisis arises
Labs supporting diagnosis of congenital adrenal hyperplasia include:
-electrolytes (low Na and high K)
-17 KS
-17 OHCS
-Cortisol
Virilization syndrome
-rare syndrome in older children and younger adults
-virilization in females
-excessive masculinization in males
Causes of Virilization syndrome:
-idiopathic adrenal hyperplasia
-adrenal cortex adenoma
-adrenal cortex carcinoma
Labs supporting diagnosis of virilization syndrome:
-urinary 17 KS elevated
-urinary 17-OHCS normal or decreased
Cushings syndrome
-excessive levels of glucocorticoids such as cortisol
What is the main cause of Cushings syndrome?
-pituitary hypersecretion of ACTH leading to bilateral adrenal cortex hyperplasia

-10% d/t adrenal cortex adenoma
-10% d/t adrenal cortex carcinoma
-10% d/t ectopic ACTH production
Is Cushings more common in males or females?
4x more common in females
Labs supporting diasnosis of Cushings syndrome?
-single determinant of cortisol is NOT adequate
-AM and PM test is better indicator
-Dexamethasone suppression test (DST) -BEST!!!
AM and PM test for Cushings disease?
AM levels = PM levels

normally highest levels occur in AM (6-10 am); PM levels are 50% of AM levels
Dexamethasone suppression test for Cushings
single best reasonably accurate screen for Cushings
LH and FSH lab tests assess:
-disorders of the menstrual cycle
-infertility
-ovarian function
-establish ovarian time
Testosterone lab tests evaluate:
-hirsuitism
-virilization
-hypogonadism
Estriol lab test evaulate:
feto-placental function
Estradiol lab tests evaluate:
ovarian function
Progesterone (serum) or Pregnanediol (urine) lab tests evaluate:
-ovulation
-function of copus luteum
PLacental hormone include...
-Human placental lactogen (HPL)
-human chorionic gonadotropin (HCG)
-prolatin
HPL levels reflect..
placental mass and function
HCG levels reflect...
pregnancy or ectopic pregnancy
Prolactin levels reflect...
placental function
Pregnancy tests
-detection is accomplished by color indicator rxn
-quick reliable result within a few minutes
-CLIA approved for in-office use
-not as sensitive as serum
Serum pregnancy test
-more senstive than urine
-quantitative hCG(peaks rapidly after conception)
-used to R/O ectopic pregnancy
-used to dx spontaneous abortion
Prostate Specific Antigen (PSA): normal levels
<4 ng/ml or <4 ug/L
PSA indications:
-screen for early prostate CA
-monitor treatment

(when combined with DRE, nearly 90% of clinically significant CA can be detected)
Where is PSA found?
-prostatic lumen
-barriers between lumen and blood stream prevent escape of PSA
-CA, infections, or BPH can broach these barriers
PSA levels with CA?
levels of >4 ng/ml are found in 80% of prostate CA cases
PSA test is limited by..
-lack of specificity with a "gray zone" of 4-10 ng/ml

-levels >10 indicate high probability of CA
What can help differentiate between CA and BPH?
% free PSA

% free PSA <25% suggests CA
Probability of CA based on % free PSA
0-10% free PSA - 56% CA
10-15% free PSA - 28% CA
15-20% free PSA - 20% CA
20-25% free PSA - 16% CA
>25% free PSA - 8% CA