Disorders of the Endocrine System, Part One (RRD #11)

The endocrine system is dependent on a series of _______ feedback systems.

negative

so...a high blood level of a circulating hormone will automatically supress the gland that secreted it and a low blood level of a circulating hormone will automatically stimulate the gland that secreted it.

Most endocrine disorders are problems of either ________ or ________.

hypersecretion or hyposecretion

What are the two problems related to the inappropriate secretion of antidiuretic hormone (ADH)?

diabetes insipidus (DI) a problem of undersecretion of ADH

syndrome of inappropriate antidiuretic hormone (SIADH) a problem of oversecretion of ADH

What are some of the potential etiologies of diabetes insipidous?

sick kidneys (which have a decreased response to ADH secretion)

a pituitary tumor or cerebral edema / IICP near the pituitary gland (causes less ADH secretion by the pituitary)

...without the influence of ADH, water will indiscriminately flow from the peritubular capillaries of the kidneys into the tubules and you will create very dilute urine.

What are the s/sx of diabetes insipidus?

polyuria, thirst, higher serum osmolality, dehydration, poor skin turgor, dry mucous membranes

What are some potential etiologies of syndrome of inappropriate antidiuretic hormone (SIADH) oversecretion?

small-cell bronchogenic cancer

various drugs that affect the brain, especially general anesthetics

trauma to the brain, head injuries, brain tumors that can cause cerebral edema, increased ICP, and put pressure on the pituitary gland (causing it to malfunction)

What are the s/sx of syndrome of inappropriate antidiuretic hormone (SIADH) oversecretion?

oliguria, edema, fluid overload

What is the job of T3 and T4?

To regulate many of the body's metabolic activities, including: the metabolic rate, caloric requirements, oxygen consumption, carbohydrate and lipid metabolism, growth and development, and brain and nervous system functions.

What is the job of calcitonin?

to increase the movement of calcium from the blood into the bone

What happens in healthy individuals when there is a drop in T3 & T4 in the bloodstream?

the pituitary gland senses the low T3 / T4 levels and releases TSH. TSH circulates back to the thyroid gland and stimulates it to release more T3 and T4 until normal serum levels of T3 and T4 are re-established. Normal levels of T3 and T4 then suppress the secretion of TSH by the pituitary.

What is Graves disease?

An autoimmune disorder in which autoantibodies attack / stimulate TSH receptors on the thyroid. This results in an increase in production of T3 and T4 by the thyroid.

What s/sx would a patient have when they are diagnosed with Graves' disease?

All s/sx are "overactive" due to the hypermetabolic processes caused by the high levels of T3 and T4. Examples of some, but not all s/sx: psych: nervous, irritable, tremors, psychosis. Cardio: tachycardia, incr. afterload, HF. GI: incr. appetite, diarrhea. Misc: exophthalmus, goiter, fatigue, weight loss, damp skin.

What is thyroid storm or thyrotoxic crisis?

The extreme state of hyperthyroidism. It is a hyperthyroid emergency and is triggered by some stressor such as infection, trauma, surgery, etc.

S/sx include: extreme restlessness and agitation, delerium, seizures, coma, severe tachycardia, HF, shock, diaphoresis, hyperthermia

What are some etiologies of hypothyroidism?

congenital defects

direct removal of tissue (tumor) or direct destruction of tissue (radiation)

autoimmune thyroiditis

endemic iodide deficiency

What does the serum lab work for a patient with hypothyroidism look like?

Serum T4 and T3 will be low, and serum TSH will be high.

What are the s/sx of a patient with hypothyroidism?

All s/sx are "hypoactive" due to the hypometabolic processes caused by the low levels of T3 and T4. Examples of some, but not all s/sx: psych: confusion, slow speech and thinking, memory loss. Cardio: bradycardia, decr. CO, anemia. GI: decr. appetite, constipation. Misc: alopecia, myxedema, goiter, cold intolerance, weight gain.

What is a myxedema coma or a myxedema crisis?

An extreme state of hypothyroidism that is precipitated by a stressor such as an infection, drug, exposure to cold, or trauma. Manifested by progression of hypothyroid sluggishness and drowsiness into gradual or sudden impaired consciousness and often hypotension and hypoventilation.

What are some of the important functions of calcium?

building and maintenance of bone density, electrical activity in the body, clotting, and others.

What two hormones regulate the movement of calcium?

calcitonin (moves calcium from blood to bone)

parathyroid hormone (PTH) (moves calcium from bone to blood by increasing osteoclastic activity)

What disorders are caused by calcium movement alterations?

osteopenia and osteoporosis

electrical issues (changes in RMP)

clotting disorders when calcium levels are low

kidney stones when calcium levels are high

Why are women more likely to have problems with a decrease in bone density?

women's bones are significantly less dense than those of men.

the menopausal loss of estrogen results in less bone building / lower bone density Was women age

What does "resorption" mean?

It is the movement of calcium out of the bone and into the blood.

What are common sequela of osteopenia and osteoporosis?

bone fractures (especially in the hip and vertebrae)

What are the most common complications of a hip fracture?

immobility, infection, DVT and PE (collectively known as VTE), fat embolism, pneumonia, hemorrhage, and shock.

Why are fat emboli a problem in long bone fractures?

Fat emboli occur when fat is released from the marrow of broken / injured long bones to systemic circulation. The fat globules can lodge in the smaller circulation of the lungs, brain, or kidney causing inflammation and ischemia.

What systems are effected by immobility?

musculoskeletal (weakness, disuse atrophy)

integumentary (skin breakdown, pressure ulcers)

pulmonary (atelectasis, pneumonia)

GI (constipation, paralytic ileus)

cardiovascular (DVT / PE, deconditioning of the cardiac system)

miscellaneous: renal calculi, osteoporosis, hypercalcemia