Endocrine testing

endocrine system function

hormones regulate body function, produced as a physiological response to stimuli

stimuli can be

internal or external

nervous and endocrine system function

transmit information through the body

how are endocrine system messages carried?

from one cell to another through hormones

what produces hormones?

ductless glands and specialized cells in endocrine

Hormones are released

into the blood for transport to target tissue

hormones structure and function

integral structure, high specificity

hormones have high

specificity and integral structure

protein hormones

polypeptides, peptides

steroid hormones

cholesterol derivative

metabolism of protein hormones

has a shorter life span than steroid hormones

steroids effect on cell

has longer effect than protein hormones

what regulates the entire endocrine system?

pituitary and hypothalamus

hypothalamus has

many neurons and is the sensing organ

what regulates the production and release of anterior pituitary hormones?

hypothalamus.

storage area for hormones

pituitary gland

which organ helps hormones release to their target?

pituitary gland

rate that hormones are released

not a steady and continuous process. It is a dynamic event in response to stimuli.

parts of the hypothalamopituitary system

pineal gland, hypothalamus, anterior pituitary, posterior pituitary

anterior pituitary hormones

growth hormone, prolactin, thyroid stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), follicle stimulating hormone (FSH), luteinizing hormone (LH)

growth hormone target tissue

bones and muscles

prolactin target tissue

breasts

Thyroid Stimulating Hormone (TSH) target tissue

thyroid

adrenocorticotropic hormone (ACTH) target tissue

adrenal cortex

Follicle-stimulating hormone (FSH) target tissue

ovary, testis

luteinizing hormone target tissue

ovary, testis

hormones of posterior pituitary

antidiuretic hormone (ADH), oxytocin

antidiuretic hormone (ADH) target tissue

renal tubules

oxytocin target tissue

uterus, breasts

primary pathological condition

involves glands that produces the hormones

secondary pathological conditions

gland that produces hormone is capable of normal function

Gigantism and acromegaly result from

hypersecretion of GH

Dwarfism is caused by:

deficit of somatotropin (growth hormone/GH)

hypersecretion of FSH or LH causes

fertility or menstruation problems

Cushing's disease

caused by pituitary tumor than secrets ACTH. more serious than syndrome. less common

syndrome of inappropriate antidiuretic hormone secretion (SIADH) caused by

hypersecretion of ADH

diabetes insipidus (not type 1 or type 2) caused by

hyposecretion of ADH. causes extreme thirst and imbalance of fluids in the body. individual will produce large amounts of urine.

thyroid disorders are

most common endocrine abnormality

thyroid is located

between the larynx and the windpipe at the base of the throat

types of thyroid cells

follicular and parafollicular

follicular cells

produce thyroid hormone

parafollicular

secretes calcitonin

thyroid produces

calcitonin, T3, T4

where are thyroid hormones produced

in the cell of the follicles. include tyrosine (amino acid) and iodine.

calcitonin function

lowers serum calcium levels and inhibit bone reabsorption of calcium

parathyroid hormone

increases serum calcium levels and bone reabsorption

thyroid gland responsibility

secretion of metabolically active hormones that are essential for regulation of various metabolic functions

thyroxine (T4) contains

4 iodine atoms. some T4 is converted to T3 in the cells

Triiodothyronine contains

3 iodine atoms. it is the most physiologically active form of thyroid hormone

Thyroid Stimulating Hormone (TSH) function

stimulates thyroid gland to release T4 and T3.

most important aspect of thyroid hormonogenesis

iodine metabolism

What happens when free T3 sand T4 are released into the bloodstream

they enter the body cells and become an intracellular pool of hormones and take affect. They are transported to the brain and pituitary gland

free T3 and free T4 function

regulate pituitary TSH secretion

how are protein bound thyroid hormones transported?

thyroxine binding globulin (TBG), thyroxine binding prealbumin (TBPA), albumin

how are free thyroid hormones transported in the blood?

they are metabolically active. Free T3 is more metabolically active than free T4.

free thyroid hormones are what %

< 1% of total

thyrotropin-releasing hormone (TRH) biofeedback

TSH --\> thyroid hormones --\> pituitary gland or hypothalamus --\> TRH --\> starts over

increase in T3 and T4

decreases release of TSH (part 1 of biofeedback)

decrease in free T4 and T3

increases release of TSH (part 2 of biofeedback)

thyroid hormones regulated by

negative feedback loop involving TRH, and TSH

decreased levels of thyroid hormones causes

hypothalamus to produce thyrotropin releasing hormone (TRH)

production of TRH attaches to

receptor sites on pituitary gland and causes an increase of TSH

pituitary increases secretion of TSH, which increases

thyroid hormone production

thyroid hormone affects these organ systems

cardiac, metabolism, central nervous system, gastrointestinal

hyperfunction of thyroid hormones

insomnia, brain fog, muscle weakness, weight loss, tachycardia

hypofunction of thyroid hormones

easily tired, poor memory, sore muscles weight gain, slow pulse, low blood pressure

diagnosis of thyroid disease

T4, free T4, T3, free T3, reverse T3, thyroid hormone binding ratio, free T3, free T4, and TSH, T3 resin uptake (T3UP), free thyroxine (T4) hormone index), thyroid antibodies

majority of lab test deal with

T3, T4, TSH

lab findings in thyroid disorders

T3/free T3, T4/free T4, T3 resin uptake (T3UP), free thyroxine hormone index (FT4I (capital i)), TSH

TSH clinical significance

helps detect hypo and hyperthyroidism

hypothyroidism

TSH levels are increased. Decrease in T3 and T4.

hyperthyroidism

TSH levels are very low or almost non-detectable (less than 0.1 uU/ml. Too much free T3 and T4

ultrasensitive TSH

sensitive TSH methods with free T4 are used as initial tests screening for thyroid disease

thyroid antibodies

thyroid antimicrosomal antibody, anti-microsomal antibody

thyroid antibodies are present in autoimmune disorders like

Graves disease, Hashimoto's thyroiditis

most important thyroid tests

ultrasensitive TSH, free T4

free T3 or free T4 specimen requirements

serum

free T3 or free T4 special requirements

do not collect immediately after administration of heparin. cannot be lipemic

free T3 or free T4 methodologies

immunometric. chemiluminescent labeled monoclonal antibodies

TSH specimen

serum

TSH special requirements

remove from RBCs, analyze at room temp

TSH methodologies

MEIA, ultrasensitive methods are best

Graves Disease

autoantibodies bind to TSH receptor sides in thyroid. Increases production of thyroid hormones. Most common type of hyperthyroidism

Thyroiditis

type of hyperthyroidism. Inflammation of thyroid. Causes rupture of cells and release of thyroid hormones

thyroid tumors

can cause hyperthyroidism. Secretes human chorionic gonadotropin (HCG), which acts as a weak thyroid stimulant

treatment of hyperthyroidism

remove excess tissue and thyroid blocking drugs

Hashimoto's thyroiditis

loss of thyroid tissue by infiltration of lymphocytes. autoimmune disorder

thyroid removal/removal of parathyroid glands

can cause hypothyroidism

radiation treatment from throat cancer

can cause hypothyroidism

treatments for hypothyroidism

thyroid hormone replacement, Synthroid

uTSH reference interval

0.5 - 5.0 uU/ml

T4 reference interval

4.5- 13.0 ug/dl

free T4 reference interval

0.8 - 2.3 ng/dl

adrenaline is produced in

adrenal glands. it important for ION homeostasis

adrenal cortex hormones

aldosterone, cortisol

adrenal medulla hormones

catecholamine hormones

acquired diseases of adrenal cortex

Cushing's disease/Cushing's syndrome, Addison's disease, Pheochromocytoma

Inherited diseases of adrenal cortex

congenital adrenal hyperplasia, inherited disorder associated by absence of enzymes needed for cortisol production

Addison's disease

adrenal glands do not produce enough of the hormones cortisol or aldosterone

Conn's disease

Hyperaldosteronism