Ch: 13 - Altered Hormonal & Metabolic Regulation

Describe the function of hormones within the body, what do they do?

Hormones are chemicals, formed originally in tissues or organs, which affect growth and / or function of other target tissues or organs. The structure of hormones can vary in composition from a single amino acid, such as with thyroid hormone to a complex combination of proteins, carbs, or lipids, as with cortisol.

What are the functions of hormones?

Fluid & electrolyte balance, sexual development & reproduction. Hormones are also instrumental in the stress response.

How do hormones facilitate feedback mechanisms, what do they do?

Hormones act as chemical messengers that travel through the bloodstream to target organs & cells, driving the body’s feedback loop to maintain internal stability (homeostasis). The most common is negative feedback, which is like an internal thermostat. The hypothalamus & pituitary act as sensors that are constantly gauging hormone levels in the body.

Define stress:

The bodies reaction to harmful forces (stressors) capable of disturbing homeostasis.

How does the body react to stress?

An individuals response to stress depends on many factors such as age, experiences, general health, type of stressor, persistence of stress, social support, & genetic influence. Homeostasis is dependent on an adequate response to stress through mobilizing energy, activating, defense mechanisms, & repairing any damage. An inadequate response or even excessive response to stress can result in destruction of body tissues. The neuroendocrine response & hormones play a vital role in this process.

What is the autonomic nervous systems response to stress?

Increased heart rate & blood pressure, pupil dilation, dry mouth, increased sweating of hands, & increased coagulability of blood.

Define general adaptation syndrome.

A term used to describe neuroendocrine response & the corresponding physiologic changes its divided into 3 major stages.

1.) Alarm stage

2.) Resistance stage

3.) Exhaustion stage

What happens if the body is continually under stress for long period of time?

Hypercortisolism is detrimental, leading to exhaustion of inflammatory & immune response, excessive loss of body proteins & breakdown of tissues , & glucose intolerance. Hormones are also suppressed.

List some ways hormone function can be altered.

-Impairment of endocrine secreting gland

-Lack of hormone synthesis

-Impaired receptor binding

-Impaired feedback mechanisms

-Altered cellular response to hormone

Definition of Hyperthyroidism

A state of excessive thyroid hormone. Can result from excessive stimulation to the thyroid gland, excess production of TSH by pituitary adenoma. Certain medications containing large amounts of iodine such as cough expectorants.

Pathophysiology of Hyperthyroidism

Excess synthesis and secretion of thyroid hormones (T₄ and T₃) or the release of preformed hormones into the bloodstream

Complications of Hyperthyroidism

Graves Disease, an excessive stimulation of the thyroid gland, this is the most common cause of hyperthyroidism, and the most common autoimmune disorder in the U.S.

A thyrotoxic crisis, or thyroid storm, is a sudden severe worsening of hyperthyroidism.

Clinical manifestations of Hyperthyroidism

Enlargement of the thyroid gland

Weight loss

Agitation

Restlessness

Sweating, heat intolerance

Diarrhea

Tachycardia

Exophthalmos (protrusion of eyeballs)

Diagnostic Criteria for Hyperthyroidism

Enlarged & firm thyroid

TSH levels are greatly suppressed (caused by negative feedback)

Elevated T₄ and T₃

Treatment of Hyperthyroidism

Reducing thyroid hormone levels

Radioactive iodine

Medication

Full removal / ablation of thyroid gland

Define Hypothyroidism

A state of deficient thyroid hormone.

Pathophysiology of Hypothyroidism

Occurs when the body lacks sufficient thyroid hormones (mainly thyroxine or T₄, and triiodothyronine or T₃), leading to a generalized slowing of the body's metabolic rate

Clinical manifestations of Hypothyroidism

Fatigue

Cold intolerance

Weakness

Weight gain

Dry skin

Coarse hair

Constipation

Lethargy

Impaired reproduction

Impaired memory

Diagnostic criteria

Laboratory studies include the sensitive TSH assay, free T4, total T4, T3 uptake, thyroid autoantibodies, and antithyroglobulin tests to confirm the diagnosis and provide evidence as to causality. Serum thyroid hormones may be decreased, and TSH is often elevated.

Treatment of Hypothyroidism

Treatment focuses on replacing deficient hormone to normalize TSH. T4, and T3 levels, along with alleviating the clinical signs and symptoms. Lifelong thyroid hormone replacement therapy is initiated and increased gradually until optimal hormone levels and clinical improvement are achieved. The most common drug used to treat hypothyroidism is levothyroxine (Synthroid, Levoxyl). Levothyroxine is a synthetic form of T4.

Define Addison Disease

Although rare, acute ACTH deficiency is considered one of the most serious endocrine disorders because it can lead to severe hypotension, shock, and death. Adrenal cortical insufficiency adrenal cortex. Disease typically occurs when 90% or more of the adrenal cortises are destroyed or nonfunctional.

Pathophysiology of Addison Disease

Primary adrenocortical insufficiency occurs as a result of insufficient production of cortisol and aldosterone from the adrenal cortex. Autoimmune destruction of layers of adrenal cortex is the most common cause.

Clinical manifestations of Addison Disease

Insufficient levels of steroid hormones

Elevation in ACTH levels stimulate skin melanocytes

Hyperpigmentation

Diagnostic criteria for Addison Disease

Electrolyte levels: hyponatremia & hyperkalemia

Treatment of Addison Disease

In acute illness, isotonic IV fluid replacement is infused along with hydrocortisone sodium succinate or hydrocortisone sodium phosphate. Blood pressure improvement should occur within 4 to 6 hours. Gradually, the IV infusion of hydrocortisone is tapered and oral replacement of glucocorticoids and mineralocorticoids ensues for the remainder of the individual’s life. Because of elevations in sodium excretion, salt intake may need to be increased in hot weather.