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185 Cards in this Set

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__% of the body's calcium is in bone, and __% is in plasma
99% in bone

1% in plasma
Calcium occurs in plasma in these three forms:

Which form is the biologically active form?
Ionized (50%)
Bound to protein (40%)
Complexed to phosphate/bicarbonate/citrate (10%)

Biologically active: Ionized
How does acidosis affect plasma calcium level?
Acidosis causes hypercalcemia.

Hydrogen and calcium bind albumin competitively, thus when H+ is increased, Ca2+ is liberated from albumin.
How would a decrease in albumin affect calcium concentration?
It would cause a decrease in bound Ca and total Ca. Free Ca2+ would not be affected.
Calcium salts are excreted by the kidney (T/F)
True; they are filtered and cannot be reabsorbed
This enzyme converts 25(OH) vitamin D to 1,25-dihydroxy-vitamin D
1-alpha-hydroxylase
This enzyme converts Vitamin D3 to 25-hydroxy-vitamin D
25-hydroxylase
Which molecule is converted by light energy to Vitamin D3?
7-Dehydrocholesterol
Scientific name for the active form of Vitamin D
1,25-dihydroxycholecalciferol
Physiologic function of Vitamin D/DHCC
Allows transmembrane proteins in the intestine and PCT to absorb calcium Ca(2+) and PO4(3-)
Active vitamin D deficiency causes ____ in children and ____ in adults
Rickets (children) and Osteomalacia (adults)
What stimulates the parathyroid glands to secrete PTH?
Decreased free (ionized) calcium concentration
How does PTH affect:
Bone
Nephron PCT
Digestion
Bone: enhances osteoclast activity, resulting in release of ionized calcium and phsophate

PCT: ehnaces caclium reabsorption, while inhibiting phosphate reabsorption

Digestion: enhances calcium absorption from food
Increased PTH (increases/decreases) the production of 1,25-dihydroxycholecalciferol
Increase; body needs more active vitamin D to absorb calcium in the GI tract
Site of production of calcitonin
Parafollicular or C-cells of the thyroid gland
what stimulates the production of calcitonin?
Increased plasma Ca concentration
What are the physiologic effects of calcitonin?
Inhibits osteoclast activity in bone and increased excretion/decreased reabsorption of Ca in the kidney
Symptoms of hypercalcemia include:
GI symptoms
Neurologic changes
Kidney stones
Osteopenia
Coma (extreme)
Most frequent cause of hypercalcemia

other causes?
Primary hyperparathyroidism

Other: malignancy, sarcoidosis, Vitamin D overdose, immobilization
Symptoms of hypocalcemia
Tetany, spasms and convulsions
What are symptoms of primary parahyperthyroidism?
Thin bones, increased risk of fracture, altered mental status and kidney stones
Lab results of primary hyperparathyroidism
Increased: calcium (serum and urine), ALP (bone), phosphate (urine), PTH

Decreased: serum phosphate
How does ectopic PTHrP cause hypercalcemia?
PTH related protein (PTHrP) is similar to the N-terminal of PTH and has the same physiologic effect on osteoclasts, kidney, etc.

PTHrP does not respond to negative feedback
do PTH and PTHrP cross react in assays?
No, they react indepedently of one another
How does primary hyperparathyroidism differ from secondary?
Primary: usually caused by adenoma/hyperplasia

Secondary: caused by hypocalcemia caused by chronic renal disease, vitamin D deficiency, intestinal malabsorption, etc.
CaI is decreased in secondary hyperparathyroidism (T/F)
True; secondary hypoparathyroidism is usually the result of chronic renal disease, which causes decreased Ca2+ reabsorption
How does acute pancreatitis affect calcium?
causes acute hypocalcemia
- increased fatty acids (due to inc. lipase) bind free calcium
- malabsorption of calcium may cause increased PTH production
How does hypomagnasemia affect calcium levels?
It causes hypocalcemia due to inhibition of PTH secretion and ineffective PTH binding to receptors in bone.
Phytic acid
Plant chemical that binds dietary vitamin D and prevents its absorption
Removal of the parathyroid gland will cause ______, which produces what symptoms?
Primary hypoparathyroidism

symptoms: tetany, drying skin, brittle hair, hypotension and GI issues
Treatment of primary hypoparathyroidism
High dosage Ca(2+) and vitamin D
Pseudohypoparathyroidism
PCT resistant to effects of PTH
- PTH is produced, but does not correct hypocalcemia
- increased plasma phosphate
- decreased plasma calcium and vitamin D
- increased ALP
Symptoms of pseudoparathyroidism
renal osteodystrophy
Paget's disease
hyperactivity of osteoclasts, causing increased calcium, phosphate and ALP, while PTH is decreased due to negative feedback by calcium.

Phosphate remains elevated due to decreased PTH
How do lab results of osteoporosis differ from the -parathyroidisms?
Osteoporosis will have no abnormal Ca/phsophate/ALP/PTH/VitD results
This molecule is increased in urine with osteoporosis
Pyridnoline
Sample requirements for calcium measurement
Whole blood/serum/plasma that:
- has not been exposed to air
- has heparin anticoagulant
- Iced down
- <1 hr old
The ionophore in calcium ISE
octyl-phenyl-phosphonate
What is another name for the dye-binding method of calcium measurement
Arsenzo method
How can the Arsenzo method for calcium measurement be modified to account for magnesium
By adding 8-hydroxyquinoline, which will complex free Mg2+
What pH level should be maintained for the Arsenzo method?
alkaline (pH>10) - 8-hydroxyquinoline will bind calcium instead of magnesium at more acidic pH
Reference range for total calcium
8.6-10 (-10.6 in children) mg/dL
Which other lab result should be looked at when looking at calcium levels
Albumin (decreased albumin means decreased total calcium)
Severe hypophosphatemia is common in this group of disorders
Acid-base disorders (ie. resp. alkalosis, DKA)
Hyperphosphatemia is associated with _____
renal insufficiency
Magnesium is predominantly (intracellular/extracellular)
Intracellular
Hypermagnesemia can be caused by which conditions?
renal insufficiency
overdose of Mg containing medication (ie. antacids)
hemolysis
The colloid in the thyroid gland has which physiologic function?
Receiving and storing thyroglobulin produced by follicular epithelial cells
The parafollicular cells of the thyroid produce and secrete:
Calcitonin
The general function of all thyroid hormones include:
- stimulation of metabolism
- growth, maturation and sexual development
- protein synthesis
- heart rate and contraction
- neurologic development
This element is key to the synthesis of thyroid hormones
Iodine (ingested as iodides)
Iodides are passively transported into the thyroid follicles (T/F)
False; it is an energy-dependent, active transport mechanism
Which enzyme is responsible for adding iodides to tyrosine to make MIT and DIT
thyroid peroxidase
monoiodotyrosine and diiodotyrosine are used to make
T3 (DIT+MIT) and T4 (DIT+DIT)
Primary site of the diodination of T4 to make T3
Liver
Which hormone induces the releace of thyroxine-thyroglobulin complexes from the follicular colloid
TSH
Thyroxine hormones bind to which three proteins in plasma?
Thyroxine-binding globulin
Thyroxine-binding prealbumin
Albumin
How is thyroxine concentration affected by pregnancy?
Increase in estrogen causes an increase in TBG; this causes an increase in total T3 and T4
How is thyroxine concentration affected by liver disease?
Decreased levels of TBG, which is synthesized by the liver, causes decreased total T3/T4
Which endocrine gland(s) responds to decreased levels of free T4 by producing and releasing TRH?
Hypothalamus
Which endocrine gland(s) responds to decreased levels of free T4 by producing and releasing TSH?
Anterior pituitary
Which is more physiologically active: T3 or T4?
T3
The concentration of circulating T3 is higher than that of T4 (T/F)
False; T4 is higher than T3, but T3 is more physiologically active
A T3 assay is order when clinicians suspect...
subclinical hyperthyroidisms when free T4 is normal
Why are lowered T3 levels typically not clinically significant?
They are commonly depressed during any chronic illness
Reference range of TSH
0.5 - 5.0 uIU/mL
Direct physiologic effects of TSH
- Increases size and number of follicular thyroid cells
- breaks down thyroglobulin to release more thyroid hormone into circulation
Describe the formation of a goiter
Decreased levels of iodide cause the anterior pituitary to secrete more TSH. The TSH causes enlargement/swelling of the thyroid gland to enhance absorption of any iodide
an increased risk of thyroid cancer after exposure to radioactivity is due to...
The thyroid extracting radioactive iodides that is inhaled from contaminated air
What can be administered to prevent uptake of radioactive iodine?
oral dose of potassium iodide, this prevents uptake of radioactive iodine by the thyroid
What symptoms may lead clinicians to suspect elevated thyroid hormones?
Increased body temp, BMR, cardiac output, RR, altered mood and behavior
Toxic adenoma, toxic multinodular goiter and Graves' disease are examples of:
primary hyperthyroidisms
In primary hyperthyroidism, total/free T3/T4 will be (inc/dec), TSH will be (inc/dec) and TRH will be (inc/dec)
T3/T4: increased
TSH: markedly decreased
TRH: decreased (rarely measured)
Symptoms of hyperthyroidisms
weight loss, sweat, anxiety, tremors, goiter, exophthalmosis, muscle weakness, tachycardia, hyperthermia
What is the most common cause of thyrotoxicosis?
Graves' disease
Physiologic cause behind Graves' disease
Production of an antibody that resembles TSH, which inappropriately stimulates the thyroid to produce excess T3/T4 - this leads to hyperthyroidism

- TSH will be normal to decreased
Cretinism is due to:
congenital primary hypothyroidism
Lab results for primary hypothyroidism
Increased TSH; decreased total/free T3/T4
Which lab tests are needed to look for congenital hypothyroidism?
First, T4 is measured. If T4 is low, then TSH is measured to determine this is secondary.
Newborns normally have (higher/lower) concentrations of T4 than adults
higher
Myxedema is a type of ____ ____ and its symptoms are...
Primary hypothyroidism; symptoms: goiter, thickening skin, hoarse speech, weight gain
Hashimoto's thyroiditis is caused by
Autoantibodies against thyroglobulin, leading to maasive infiltration of the thyroid by lymphocytes
What is the most common cause of primary hyperthyroidism?
Hashimoto's thyroidits
In adults, the first lab test ordered when a thyroid problem is suspected should be:
TSH
A TSH level of <0.1 mU/mL is suggestive of
primary hyperthyroidism
When is a free T4 index performed?
When analyzed TSH results do not correlate to clinical symptoms
Abnormal levels of thyroxines in the presence of normal levels of TSH can be due to:
pregnancy or liver disease, due to abnormal levels of TBG
The eurythroid sick syndrome occurs when:
fT3 and fT4 are decreased but the thyroid and pituitary glands are functioning normally; occurs due to many types of illnesses
Should thyroid function tests be performed on seriously ill patients?
No, due to the common presence of euthyroid sick syndrome
How are thyroxine levels analyzed?
Competitive immunoassay:
1. Thyroxines are displaced from carrier proteins
2. Antibodies specific for thyroxine are added
3. Enzyme-labeled thyroxine compete with patient's thyroxine for Ab binding sites
4. Wash removes unbound thyroxines
5. Substrate that reacts with enzyme-label and produces a color change is added
6. Color intensity is inversely proportional to patient's thyroxine level
THBR is (inversely/directly) related to TBG levels
inversely; increased THBR indicates low levels of TBG
What is the purpose of the TRH stimulation test?
To determine if a patient has hyperthyroidism. TRH will cause a rapid increase in TSH in normal patients, but no response in hyperthyroid patients.
What is the purpose of TSH receptor antibodies?
Detects TSHr-Ab's in order to diagnose autoimmune hyperthyroidisms (ie. Graves' disease)
Why is the analysis of free T4 problematic?
The vast majority of T4 is bound to TBG. Any slight disturbance or deviation in procedure will cause a falsely elevated FT4.
Hormones produced by the adrenal gland are what type?
Steroid
A defect in (11-beta) has what effect on adrenal hormones?
11-beta is required to produce cortisol and aldosterone

a defect will cause inability to produce these and an elevated level of sex hormones
Aldosterone is secreted by the ____ of the ____
zona glomerulosa of the adrenal cortex
This hormone is responsible for:
- sodium reabsorption in the PCT
- regulation of extracellular fluid volume
- increasing blood volume and pressure
Aldosterone
Aldosterone
- sodium reabsorption in the PCT
- regulation of extracellular fluid volume
- increasing blood volume and pressure
This enzyme is stored in JG cells of the renal glomeruli and is the first step of aldosterone up-regulation
Renin
Renin production is stimulated by:
low plasma volume/pressure and hyponatremia
Renin converts _____ to ____
angiotensinogen to angiotensin I
Angiotensin I is converted to angiotensin II in the ____ by ____
lungs, by angiotensin-converting enzyme
Angiotenin II causes _____
vasoconstriction
Where is cortisol produced?
Zona fasciculata of the adrenal cortex
17-hydroxycorticosteroids are precursors of _____
cortisol
Physiologic functions of cortisol
- Increased gluconeogenesis in liver
- Suppression of insulin secretion
- Inhibition of peripheral uptake of glucose
- Inc. glycogenesis, proteolysis
- inc. fatty acid production via cellular lipase
- stimulates erythropoiesis
How does cortisol have an anti-inflammatory effect?
- suppression of cytokines
- inhibition of leukocyte transport across capillary
- decrease eosinophils and T-lymphocytes

!! too much can cause poor wound healing and immunosuppression
Corticotropin Releasing Hormone is secreted by the _____ in response to _____
Hypothalamus; decreased levels of plasma cortisol
CRH stimulates the _____ to secrete _____
anterior pituitary; ACTH (adrenal corticotropic hormone)
ACTH stimulates the _____ to secrete _____
zona fasciculata (Zone F) of the adrenal cortex; cortisol
ACTH is increased in the evening and decreased in the morning (T/F)
False; ACTH levels increase exponentially at night and peak in the morning, then decrease
When females are exposed to an excess of testosterone or androstenedione, this can cause:
- virilization (development of masculine characteristics)
- cessation of menstruation
The zona reticularis of the adrenal cortex produces _____
Precursors to androgens: DHEA and androstenedione from cholesterol
Hormones produced by the adrenal medulla
Norepinephrine and epinephrine
Norepinephrine is synthesized primarilly in the ____

Epinephrine is synthesized primarilly in the ____
NorE: CNS
Epi: adrenal medulla
Physiological effects of catecholamines
- released in response to pain or emotional disturbance
- slows digestion
- increased BP, HR, blood glucose
- arterial dilation
Metabolites of catacholamines are converted to ____
Vanillymandelic acid (VMA)
How is stimulation of tissue by catecholamines different from direct stimulation by the sympathetic nervous system?
Th effects of hormones are longer lasting and the hormones can reach tissues that are not directly innervated
Catecholamines are synthesized from which amino acid?
Tyrosine
Catecholamines bind alpha receptors to increase ____ and decrease ____
Free calcium; cAMP
The action of catecholamines to bind beta receptors serves to:
- increase heart rate
- increase force of contraction
What are the effects of catecholamines with regards to energy storage and utilization?
Catecholamines:
- increase glycogenolysis
- stimulate lipolysis (more sustained energy production than glycolysis)
- increased metabolic rate, O2 consumption and heat production
Excessive consumption of licorice is linked to ____
hyperaldosteronism
Lab results of hyperaldosteronism
- normal to elevated Na
- decreased K
- increased serum/urine aldosterone
- metabolic alkalosis
What is the difference between the etiology of primary and secondary hyperaldosteronism?
Primary: caused by adrenal adenoma or adrenal hyperplasia [renin will be decreased due to kidney response to low BP]

Secondary: Excessive renin production in the kidney resulting in hyperaldosteronism
PTH is required for the synthesis of 1,25-dihydroxycholeclaciferol (T/F)
True
Lab results for hypoaldosteronism
- decreased plasma sodium
- increased potassium [metabolic alkalosis]
- decreased aldosterone
- decreased blood pressure
What is the difference between primary and secondary adrenal insufficiency?
Primary insufficiency occurs with a damaged or ineffective adrenal cortex

Secondary insufficiency occurs due to a deficiency of ACTH (pituitary issue)
Lab results of primary adrenal insufficiency
Decreased: cortisol, aldosterone, sodium, blood pressure, pH(acidosis)

Increased: potassium, ACTH
Symptoms of Addison's disease
dehydration, decreased kidney function, shock (due to low BP), darkening of skin due to MSH
Primary hypercortisolism is also known as ____
Cushing's syndrome
Why does Cushing's syndrome cause hyperglycemia?
Cushing's syndrome causes elevated levels of cortisol. Cortisol induces gluconeogensis and glycogenolysis and increases blood glucose.
The characteristic physical features of Cushing's syndrome:
Buffalo hump: Trunkal obesity and fat accumulation on the upper shoulders

Moon face: fluid and tissue accumulation around the face

Also: poor wound healing, weight gain, weakened bones, depression
What are the lab results of primary Cushing's syndrome
Hyperglycemia, cortisoluria

Inc. cortisol in the morning AND evening, while ACTH is decreased in the morning
What lab result will differentiate primary and secondary hypercortisolemia
In the morning:
Primary: ACTH decreased
Secondary: ACTH increased
What is ectopic Cushing's disease?
Secondary hypercortisolism due to an ACTH-producing tumor located outside of the pituitary gland.
Hypocortisolism is also known as ____
Addison's disease
Insulin sensitivity, hypoglycemia, weakness and imbalances in carb/fat/protein metabolism are associated with ____
Addison's disease
A rise in cortisol levels after administration of synthetic ACTH is due to
Secondary pituitary failure or medication-induced adrenal atrophy
After administration of metyrapone, the levels of 11-deoxycortisol will be increased in _____, but decreased in _____
Increased: normal pituitary response

Decreased: pituitary or hypothalamic diseas
The metyrapone stimulation test can be safely performed in those with primary adrenal insufficiencies (T/F)
False; primary adrenal insufficiency must first be ruled out, as the test will cause unnecessary stress to the patient
When measuring urine cortisol, what must be done to separate urinary free cortisol from cortisol metabolites?
An organic solvent is added and the metabolites are extracted
A deficiency in 21-hydroxylase will cause increased ____. Because of this ____ and ____ will be decreased
Cortisol and aldosterone precursors will be shunted to produce adrenal androgens.
When drawing to test for plasma epinepherine levels, what important factor must be considered?
The patient's posture; levels may be much higher in standing/sitting patients than those that are supine.
Laboratory signs indicative of a pheochromocytoma are
Blood catecholammines: >2,000 ng/L

Urine VMA: >11 mg
Clonidine will not affect the catecholamine levels when an adrenal tumor is present (T/F)
True; clonidine suppression test is used to discriminate adrenal tumors from other causes of hypertension
Estradiol (E2)
- chief estrogen in non-pregnant females
- produced by the maturing follicle within the ovary
- Responsible for secondary sexual chars., fat distribution, uterine development, preparation of the uterus for implantation/pregnancy
Estrone (E1)
Metabolic product of estradiol with no biological activity
Estriol (E3)
- synthesized by placenta using a precursor made by the developing fetus
- high concentrations during pregnancy suppress pituitary hormones that cause ovulation
- present in very small quantities in non-pregnant women
_____ is the chief male androgen, while ____ is the chief female androgen
Testosterone = male
Androstenedione = female
Dihydrotestosterone has (greater/lesser) biological activity than testosterone
Greater
Functions of testosterone
- male secondary sexual chars. (muscle, bone, voice, hair)
- maturation of male reproductive system
- spermatogenesis
Progesterone is produced by the ____ in women
corpus luteum (luteal phase) and placenta (during pregnancy)
Function of progesterone
Induces growth and vascularization of the uterine wall in preparation for implantation of the fertilized egg
GnRH stimulates the ______ to secrete ___ and ___
anterior pituitary; LH and FSH
Oxytocin is produced by the _____ and stored by the ____ until secretion is stimulated
hypothalamus; posterior pituitary
This hormone is responsible for stimulating growth and mitosis/meiosis of gametes
Follicle stimulating hormone (FSH)
This hormone is responsible for release of gametes by stimulating secretion of progesterone/testosterone from the ovary/testis, respectively
Luteinizing hormone (aka interstitial cell-stimulating hormone)
Decreased testosterone in males leads to an increase in which hormones?
LH and FSH
Estradiol inhibits the release of ___ from the ant. pituitary, while stimulating it to secrete ___
FSH is inhibited while LH is stimulated
Ovulation
The release of a mature oocyte from the follicle. Ovulation is induced by a surge in LH/FSH, which arises due to rising estradiol
The pituitary is stimulated to produce FSH and LH by ____, ____ and ___
GnRH, decreased estradiol and decreased progesterone
LH, FSH and inhibin A are at their highest levels on day __ when ____ occurs
14; ovulation
What triggers menstruation?
A decrease in estradiol and progesterone due to the destruction of the corpus luteum
After implantation, the ____ starts producing progesterone, estrogen and hCG
placenta
During pregnancy ___ inhibits the secretion of FSH and LH
Estriol (E3)
A typical uncomplicated pregnancy lasts ___ weeks
40
The stage of stage of the embryo that implants in the uterus is the ____
blastocyst
hCG levels increase rapidly after ___ and peak at ___ (unit of time)
implantation; 12-14 weeks (1st trimester)
hPL
human placental lactogen; marker of pregnancy; prepares mammary glands for lactation
A common cause of maternal death during the first trimester
Ectopic pregnancy: fertilized ovum is unable to implant the uterus
Scarred or obstructed fallopian tubes due to STD or PID is a common cause of ____
ectopic pregnancy
During an ectopic pregnancy, hCG will be ____
Low, with a much slower rate of increase compared to normal pregnancy
Most spontaneous abortions during the first trimester occur due to:
fetal abnormalities, such as genetic defects and incompatibilities with life
A sudden drop in progesterone levels DURING pregnancy will cause:
Endometrium, with the developing embryo, to slough and cause menstruation/miscarriage
Hydatiform mole
benign growth, characterized by abnormal growth of chorionic villi, edema and fluid-filled sacs in the uterus visible by ultrasound
Choriocarcinoma
An invasive malignancy that arises from the trophoblast (outer layer of cells in a blastocyst)
Extremely high levels of hCG (>400,000) are consistent with:
A choriocarcinoma with poor prognosis
hCG levels in a twin pregnancy will be ___ the normal level
double
Menopause is marked by an increase in ____ and decrease in ____
FSH and LH become elevated, while estrodiol decreases.
Signs of hypogonadism (children vs. adults)
Children: delayed onset of puberty

Adults: amenorrhea, decreased libido, infertility
Turner's syndrome and Klinefelter's syndrome are examples of:
Primary hypogonadisms
Primary vs. Secondary hypogonadisms
Both: dec. gonadal hormones
Primary: inc. FSH/LH
Secondary: dec. FSH/LH
Hirsutism
Excessive hair growth in women where hair should not normally be seen (back, chest, face)