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Clinical Chemistry (Hormones)
Terms in this set (35)
What are tropic hormones?
Hormones produced by one endocrine gland that regulate another endocrine gland. For example, the hypothalamus secretes tropic hormones that stimulate the anterior pituitary. The anterior pituitary produces thyroid stimulating hormone (TSH), which stimulates the thyroid gland, and adrenocorticotropic hormone (ACTH), which stimulates the adrenal cortex.
What type of method is used for most hormone assays?
What is the precursor in the biosynthesis of all steroid hormones?
What are some examples of steroid hormones?
Cortisol, aldosterone, estrogen, testosterone, progesterone.
Where is follicle-stimulating hormone (FSH) produced and what is its main action?
It is produced in the anterior pituitary. It stimulates production of sperm and eggs. There is a sharp increase in FSH just before ovulation.
Where is growth hormone (GH) produced and what is its main action?
It is produced in the anterior pituitary. It stimulates protein synthesis and cell growth and division.
Where is thyroid-stimulating hormone (TSH) produced and what is its main action?
It is produced in the anterior pituitary. It stimulates the thyroid to produce T3 and T4. It is also known as
Where is adrenocorticotropic hormone (ACTH) produced and what is its main action?
It is produced in the anterior pituitary. It stimulates the adrenal cortex to produce corticosteroids. ACTH exhibits diurnal variation, with highest levels in the early morning and lowest levels late in the day
Where is anti-diuretic hormone (ADH) produced and what is its main action?
It is produced in the hypothalamus and stored in the posterior pituitary. It regulates reabsorption of water from the distal convoluted tubules. ADH is decreased in diabetes insipidus, leading to the excretion of an increased volume of dilute urine
Where is cortisol produced and what is its main action?
It is produced in the adrenal cortex and regulates carbohydrate, fat, and protein metabolism, water and electrolyte balance, and suppresses inflammatory and allergic reactions.
What is Addison disease?
Adrenal insufficiency, characterized by decreased cortisol and increased ACTH. (This is an example of feedback
control. The ACTH is increased because of the decreased cortisol; however in Addison disease, the adrenal gland is
unable to respond appropriately to the ACTH.)
What is Cushing syndrome?
The signs and symptoms associated with elevated cortisol levels. Cushing syndrome may be due to tumors of the
pituitary (Cushing disease), tumors of the adrenal glands, ectopic ACTH-secreting tumors, or administration of
glucocorticoids or ACTH.
What is the advantage of a 24-hour urine free cortisol measurement?
It is not affected by circadian variation and is the most sensitive and specific screen for excess cortisol production. It is measured by tandem mass spectroscopy.
Where is aldosterone produced and what is its main action?
It is produced in the adrenal cortex. It increases retention of Na+ and excretion of K+ and H+
What are catecholamines?
The hormones secreted by the adrenal medulla: epinephrine, norepinephrine, and dopamine. Their metabolite is vanillylmandelic acid (VMA).
Where is progesterone produced and what is its main action?
It is produced in the ovaries. It prepares the uterus for pregnancy and stimulates lactation.
What is the major estrogen produced by the ovaries?
Estradiol (E2). Estrogens are involved in the development of the female reproductive organs and secondary sex
characteristics, regulation of the menstrual cycle, and maintenance of pregnancy
Which hormones are used to assess fetal well·being?
Estriol, progesterone, and its metabolite, pregnanediol.
Which hormone can be measured by a home testing kit to determine the time of ovulation?
Luteinizing hormone (LH), secreted by the anterior pituitary. There is a sharp peak just before ovulation.
Why are estrogen and progesterone receptor assays performed?
To establish a prognosis for patients with breast cancer.
Where is thyroxine (T4) produced and what is its main action?
It is produced in the thyroid and controls metabolic rate, growth and development, and sexual maturation.
Triiodothyronine (T3) is formed primarily from deiodination of T4 by tissues.
Which is the physiologically active form of T4?
Free T4 (FT4). Most T4 is bound to thyroxine binding globulin (TBG), the main carrier protein for T4 and T3.
What is the recommended screening test for thyroid function?
Thyroid·stimulating hormone (TSH). With primary hypothyroidism, TSH may be increased before clinical
symptoms. A normal TSH usually excludes a diagnosis of primary thyroid dysfunction.
What further thyroid testing is recommended when the TSH is abnormal?
Free T4. Free T3 assays are available but are not routinely performed.
What methodology is most often used to measure TSH and free T4?
A patient has a high TSH and a low free T4. What is a likely diagnosis?
Primary hypothyroidism, a disorder of the thyroid gland. TSH increases as the pituitary tries to stimulate the
thyroid to produce more T3 and T4.
A patient bas a low free T4 and a low TSH. What is a likely diagnosis?
Secondary hypothyroidism, a pituitary disorder. The thyroid is nonnal, but it isn't stimulated to produce the nonnal amount of thyroid hormones because of insufficient TSH from the pituitary.
How can primary hypothyroidism be differentiated from secondary hypothyroidism?
By TSH. Primary hypothyroidism is a disorder of the thyroid gland. TSH increases as the pituitary tries to stimulate the thyroid to produce more T3 and T4. Secondary hypothyroidism is a pituitary disorder. TSH levels are low.
What lab findings are typical of primary hypothyroidism?
High TSH and low free T4.
What screening is done for neonatal hypothyroidism?
Measurement ofT4 or TSH or a combination of tests is performed using dry blood spots or cord blood. All 50
states require newborn screening for hypothyroidism to eliminate severe mental retardation associated with thyroid hormone deficiency.
What lab findings are typical of hyperthyroidism?
TSH is low and free T4 is high. The high level of T4 produced by the thyroid sends a feedback message to the pituitary to slow down production of TSH.
What is Graves' disease
An autoimmune disease that is the most common type of hyperthyroidism in the U.S. Thyroid stimulating hormone
receptor antibodies (TRab) are present in the serum.
What is Hasbimoto's thyroiditis
A type of autoimmune hypothyroidism and the most common cause of hypothyroidism in the developed world. It is characterized by the presence of anti-thyroid antibodies that gradually impair thyroid function, leading to decreased synthesis of thyroid hormones. The best test for diagnosing the condition is thyroid peroxidase antibody (TPOAb), which is present in 80-99% of cases. Hashimoto's is also known as chronic lymphocytic thyroiditis.
Where is parathyroid hormone (PTH) produced and what is its main action?
It is produced in the parathyroid glands. It increases serum calcium and decreases phosphates. PTH is increased in primary hypcrparathyroidism and decreased in hypoparathyroidism
Where is glucagon produced and what is its main action?
It is produced in the alpha cells of the pancreas. It increases glucose levels.
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