thyroid, reproductive, and adrenal medulla

primary hypothyroidism

TSH, free T4, T3, TRH

IDDI

secondary hypothyroidism

TSH, free T4, T3, TRH

DDDI

tertiary hypothyroidism

TSH, free T4, T3, TRH

DDDD

primary hyperthyroidism

TSH, free T4, T3, TRH

DIID

secondary hyperthyroidism

TSH, free T4, T3, TRH

N/I I I D

tertiary hyperthyroidism

TSH, free T4, T3, TRH

IIII

The three levels of dysfunction that may be evaluated in a patient with an endocrine problem are primary, secondary, and tertiary. The possible defective sites that correspond to these primary, secondary, and tertiary levels of dysfunction are, respectively:

Target gland, pituitary, hypothalamus

Secretion of hormones by the anterior pituitary is controlled by circulating levels of hormones from the target gland and hormones secreted by the:

Hypothalamus

The parent substance of all steroid hormones is:

Cholesterol

Progesterone

Parallels activity of the corpus luteum by rapidly increasing following ovulation and then abruptly falling to initial low concentrations prior to the onset of menstruation

The most potent estrogen and the substance considered to be the true ovarian hormone is:

estradiol

Which hormones are secreted by the placenta? (both protein and steroid)

Human chorionic gonadotropin (HCG)

Progesterone

Estrogen

Human placental lactogen (HPL)

NOT Luteinizing hormone (LH)

In a normal individual, injection of Thyrotropin releasing hormone (TRH) causes an increase in blood concentrations of TSH, as well as which of the following hormones?

prolactin

Calcitonin is produced in the:

Parafollicular cells of the thyroid gland

In a patient with Graves' disease, one would expect the following laboratory serum results: T4 _________, TSH _________.

Free T4 Increased, TSH decreased

In a patient suspected of having primary myxedema, one would expect the following serum results: T4 _______, TSH ________.

Free T4 Decreased, TSH increased

Which one of the following statements about T3 is true?

NOT It is about 25% bound to serum proteins such as thyroglobulin

It may be elevated to a greater extent than T4 in hyperthyroidism.

It is thought to be the most active thyroid hormone

It is commonly decreased in patients with nonthyroidal illness.

A two-year-old child with a decreased serum T4 is described as being somewhat dwarfed, stocky, and overweight and having coarse features. Of the following, the most informative additional laboratory test would be serum:

Thyroid-stimulating hormone (TSH)

The TRH (thyrotropin releasing hormone) stimulation test is useful in differentiating hypothalamic hypothyroidism from:

Pituitary hypothyroidism

Deiodination of the OUTER ring of thyroxine results in:

triiodothyronine (T3)

Which of the following is the best test to differentiate primary hypothyroidism from Hashimoto’s thyroiditis?

Anti-TPO antibodies

The FINAL metabolite of epinephrine that is measured in urine is:

Vanillylmandelic acid

In a patient who is suspected of having pheochromocytoma, measurement of which of the following compounds would be most useful?

Urine Metanephrine

Name the condition that results from of a congenital deficiency of 21-alpha-hydroxylase.

The condition with a congenital deficiency of 21-alpha-hydroxylase is congenital adrenal hyperplasia (CAH). The decreased hormones include aldosterone; the increased hormones would be ACTH and CRH.

EX: female pseudohermaphroditism.

This is a disorder of adrenal steriodogenesis, where there is excess excretion of 17-ketosteroid and pregnanetriol.

Which congenital deficiency of 21-alpha-hydroxylase, which hormones would be decreased?  Which would be increased?

Hormones that are elevated include plasma 17-hydroxyprogesterone androstenedione (17-ketosteroid, testosterone, and dihydrotestosterone), and pregnanetriol. Hormones that would be blocked include mineralocorticoids and glucocorticoids: aldosterone, corticosterone, and cortisol. 

Differentiate between production of T3 and reverse T3  - how each is formed, function of each, stimuli that favor formation of a particular form.

Forming and function of T3:

T3 and reverse T3 are both produced from free T4. FT4 is the primary secretory product of the normal thyroid gland.

In the liver, T4 manually undergoes the peripheral deionination of the T4 outer ring.

40% of secreted T4 is deiodinated in peripheral tissues to form T3. T3 is 4-5 times more potent than T4 is. They reversibly bind to carrier proteins.

Differentiate between production of T3 and reverse T3  - how each is formed, function of each, stimuli that favor formation of a particular form.

Forming and function of reverse T3 (thyroxine):

One iodine from the inner ring of T4 is removed to form reverse T3 mainly in the liver. Due to acute stress, chronic stress, or medications, reverse T3 is formed instead of T3.

45% of secreted T4 is deiodinated to form rT3, which is biologically inactive.