Finals Laboratory Exam Flashcards
Na and K, Blood Gas, PSA, Thyroid Endocrinology
A bilobed organ which are connected in the center by an isthmus.
Thyroid gland
T3 and T4 are derived from
tyrosine and iodine
The active thyroid hormones are made in the ____, the fundamental structural
unit of the thyroid gland, from tyrosine and iodine in the presence of peroxidase.
follicle
T4 is also known as
a. 3,5,3’5’ tetraiodothyronine
b. thyroxine
c. A and B
d.3,5,3’ tri-iodothyronine
T4 is also known as
a. 3,5,3’5’ tetraiodothyronine
b. thyroxine
c. A and B
d.3,5,3’ tri-iodothyronine
Around 80% of T3 is formed in
peripheral cells
inactive form of T3,
formed during chronic illness
rT3
(3, 3’, 5’)
the test is ordered when a clinician suspects subclinical hyperthyroidism when free T4 is normal. ____ is typically elevated in hyperthyroidism.
Triiodothyronine
The thyroid gland also contains ____ cells that produce calcitonin and other similar peptides.
parafollicular
This disorder is associated with increased levels of TSH and decreased free T4 levels.
Hypothyroidism
usually presents during the hypothyroid state following thyroid atrophy but may present as euthyroid with goiter due to the inflammatory state.
Hashimoto’s thyroiditis
the characteristic reaction to thyroid hormone deficiency, including puffiness in the face and surrounding the eyes due to accumulation of mucopolysaccharides and chondroitin sulfate. Other characteristics of hypothyroidism include cold intolerance, dry hair and skin, weight gain, etc.
Myxdema
Treatment involves thyroid hormone replacement
levothyroxine
is associated with both decreased TSH and free T4.
Symptoms are similar to those of primary hypothyroidism in the adult. It is gener-
ally of pituitary origin secondary to surgical removal of the pituitary or pituitary failure, such as following head trauma, cerebral vascular accident, or obstetric com-
plications.
Secondary hypothyroidism
A prohormone for T3 production
T4
Ref value for T3
Adults:
a. 60-150 ug/dL
b. 70-120 ug/dL
c. 60-160 ug/dL
Children:
a. 105-245 ug/dL
b. 120-145 ug/dL
c. 150-240 ug/dL
Ref value for T3
Adults:
a. 60 - 150 ug/dL
b. 70 - 120 ug/dL
c. 60 - 160 ug/dL
Children:
a. 105 - 245 ug/dL
b. 120 - 145 ug/dL
c. 150 - 240 ug/dL
Adults: 0.9 to 2.46 nmol/L
Children: 1.8 to 3.8 nmol/L
Ref value for T4
Adults:
a. 5.5 - 12.5 ug/dL
b. 5.0 - 10 ug/dL
c. 5.0 - 10.5 ug/dL
Neonate:
a. 11.8 - 22.6 ug/dL
b. 12 - 20 ug/dL
c. 11 - 22 ug/dL
Ref value for T4
Adults:
a. 5.5 - 12.5 ug/dL
b. 5.0 - 10 ug/dL
c. 5.0 - 10.5 ug/dL
Neonate:
a. 11.8 - 22.6 ug/dL
b. 12 - 20 ug/dL
c. 11 - 22 ug/dL
Adult: 71-161 nmol/L
Neonate 152-292 nmol/L
optic changes including exophthalmos, proximal muscle weakness, tachycardia, atrial fibrillation, hyperthermia, and weight loss or inability to gain
weight.
hyperthyroidism
this disease is characterized as a toxic diffuse goiter (an enlarged, hyperactive thyroid gland) with an immunologic origin. Patients with this disease have circulating thyroid-stimulating antibodies (TSAb). This is most likely due to a defect in suppressor T lymphocytes, which allows for antigenic stimulation by thyroid antigens and production of immunoglobulins.
Graves’ disease
is a more common cause of hyperthyroidism in older adults. The cause of hyperactive nodes in the
thyroid is unknown, but it is generally thought that it is not immunologic.
Toxic multinodular goiter, also known as Plummer’s disease
increased levels of TSH and in-
creased levels of free T4.
Secondary hyperthyroidism
decreased TSH
increased Free T4
Graves’ disease
amount of iodine expressed in micrograms per 100 milliliters of blood serum that is precipitated with serum proteins
normal value ranges from 4 to 8 μg/100mL
Protein-bound iodine (PBI)
iodine that can be separated from plasma
proteins by butanol
Reference range : 2 – 6.5 μg/100mL
Butanol-extractable iodine(BEI)
Normal reference range (RIA) :
TT4 (72-163 nmol/L)
a. 5.5 - 12.5 ug/dL
b. 5.0 - 12 ug/dL
c. 5.5 - 15 ug/dL
TT3 (1.23-3 nmol/L)
a. 80 - 200 ng/dL
b. 90 - 200 ng/dL
c. 70 - 220 ng/dL
Normal reference range (RIA) :
TT4 (72-163 nmol/L)
a. 5.5 - 12.5 ug/dL
b. 5.0 - 12 ug/dL
c. 5.5 - 15 ug/dL
TT3 (1.23-3 nmol/L)
a. 80 - 200 ng/dL
b. 90 - 200 ng/dL
c. 70 - 220 ng/dL
the gold standard – by employing this technique, TBG’s variable effect on total T4 concentration is eliminated
a. Equilibrium dialysis
b. Kinetic rate reaction
c. Coated Ab Tubes
d. Microencapsulated antibodies
which is the gold standard – by employing this technique, TBG’s variable effect on total T4 concentration is eliminated
a. Equilibrium dialysis
b. Kinetic rate reaction
c. Coated Ab Tubes
d. Microencapsulated antibodies
Mixed directly with patients serum
a. Equilibrium dialysis
b. Kinetic rate reaction
c. Coated Ab Tubes
d. Microencapsulated antibodies
Mixed directly with patients serum
a. Equilibrium dialysis
b. Kinetic rate reaction
c. Coated Ab Tubes
d. Microencapsulated antibodies
an in vitro indirect measure of the unsaturated binding sites on the thyroid hormone-binding proteins
RT3U Test
Normal value 25-35%; ratio: 0.85-1.15
use to differentiate primary hypo from secondary hypo
TSH Test
the sensitivity of the third generation TSH assays has led to the ability to detect what is termed ____ (or mild degree of thyroid dysfunction- due to the large reciprocal change in TSH levels seen for even small changes in free T4)
SUBCLINICAL DISEASE
- Measures pituitary stores
- Differentiate secondary (pituitary) from tertiary
(hypothalamic) hypothyroidism
Thyroid Releasing Hormone Stimulation Test
Main carrier of T4 and T3
◦ Helpful in patients who have serum T3 & T4 levels that don’t agree with other
Thyroid Binding Proteins (TBP)
- “Hibernate hormone”
- Produced by 5-deiodination of T4
Reverse T3 (rT3)
Used as a tumor marker to evaluate the effectiveness of treatment for thyroid cancer and to monitor its reoccurrence.
a. Colloid Ab
b. Thyroglobulin Ab
c. Microsomal Ab
Thyroglobulin Antibodies
Antibodies directed against antigen in the cytoplasm.
a. Colloid Ab
b. Thyroglobulin Ab
c. Microsomal Ab
Microsomal Antibodies
Uses 123I or 99TC to define areas of increased
or decreased uptake within the gland.
a. T3 Suppression test
b. Radioactive Iodine Uptake (RAIU) test
c. Thyroid scan
Uses 123I or 99TC to define areas of increased
or decreased uptake within the gland.
a. T3 Suppression test
b. Radioactive Iodine Uptake (RAIU) test
c. Thyroid scan
a substance that can donate hydrogen
A. Acid H+ ions
B. Base OH- ions
a substance that can donate hydrogen
A. Acid H+ ions
B. Base OH- ions
Strong acids have
pKa values of less than ___
a. 3.0
b. 4.0
c. 9.0
whereas strong bases have
pKa values greater than ___
a. 3.0
b. 4.0
c. 9.0
a. less than 3.0
c. 9.0
Through metabolism, the body produces approximately ____ of H+ each day.
150 g
____ is also known
as the ionization constant.
The dissociation constant