Insufficient levels of T3 + T4 1. Primary 2. Secondary

Thyroid Flashcards by Edward Hahn

Thyroid Gland secretes

triiodothyronine (T3) and thyroxine (T4)

How well did you know this?

Not at all

Perfectly

Thyroxine

Is the regulator of body metabolism that influences almost every body function

How well did you know this?

Not at all

Perfectly

Thyroid gland

a 2in butterfly-shaped gland located in the neck

How well did you know this?

Not at all

Perfectly

What is a necessary component in the synthesis of thyroid hormone?

Iodine

How well did you know this?

Not at all

Perfectly

Thyroid gland feedback loop

Hypothalamus: releasing hormone (TRH)
Anterior pituitary: TSH
Thyroid gland: makes T4
Thyroxine
- Negative feed back to stop Anterior pituitary and hypothalamus

How well did you know this?

Not at all

Perfectly

Most common thyroid disorders

Primary thyroid disorders

-Involves the thyroid gland itself

How well did you know this?

Not at all

Perfectly

Thyroid dysfunctions are either

Hypo or hyperthyroidism

-enlargement can occur in either

How well did you know this?

Not at all

Perfectly

Thyroid problems are more likely in who?

Women

How well did you know this?

Not at all

Perfectly

Goiter

an enlargement of the thyroid gland WITH or WITHOUT symptoms of thyroid dysfunction

Excess pituitary TSH

Low iodine levels

If NO symptoms of thyroid disease the goiter is “nontoxic”

How well did you know this?

Not at all

Perfectly

Enlargement of the thyroid gland can also occur from

Goitrogens

-substances that promote thyroid gland enlargement (lithium)

How well did you know this?

Not at all

Perfectly

Hypothyroidism

Insufficient levels of T3 + T4

Primary
Secondary

How well did you know this?

Not at all

Perfectly

Primary Hypothyroidism

Increase in release of TSH from pituitary (Excessive release of TSH indicates hypoactive thyroid)

How well did you know this?

Not at all

Perfectly

Most common type of hypothyroidism

Hashimoto’s thyroiditis

-an autoimmune disorder

How well did you know this?

Not at all

Perfectly

Hypothyroidism: Hashimoto’s

Thyroid receptor receptor antibodies
Antithyroglobulin antibody
Antithyroperoxidase antibody: HALLMARK of disorder

How well did you know this?

Not at all

Perfectly

Hypothyroidism Risk Factors

-Females
-Age >50
-Caucasian
-Pregnancy
-History of other
Autoimmune disorders
-Family Hx
-Medications (amiodarone, lithium)
-Treatment for hyperthyroidism

How well did you know this?

Not at all

Perfectly

Hypothyroidism: Manifestations (Early)

Cold intolerance
Weight gain
Lethargy
Fatigue
Memory deficits
Poor attention span
Increased cholesterol
Muscle cramps
Raises carotene levels
Constipation
Decreased fertility
Puffy face
Hair loss
Brittle nails

How well did you know this?

Not at all

Perfectly

Hypothyroidism: Manifestations (late)

Below Normal Temp
Bradycardia
Weight gain
Decreased LOC
Thickened skin
Cardiac complications (cardiomegaly)

Hypothyroidism Affects all Body Organs:

Raises cholesterol: hyperlipidemia
Raises carotene levels (yellows skin)
Causes anemia
Decreased filtration by kidney (risk of med toxicity)
Can cause hoarse voice

Myxedema

Severe hypothyroidism (coma)

Describes the dermatological change that occurs with hypothyroidism

Myxedema can be found in hypo and hyperthyroidism

Hyperthyroidism: Symptoms

Anxiety 
Tremor
Tachycardia
Feeling warm
Loss of weight
Exophthalmos
Atrial fibrillation
Decreased fertility

Diagnosing Hypothyroidism

High TSH level

Low free T3
Low Free T4

Antithyroglobulin (anti-Tg)

Antithyroperoxidase (anti-TPO) antibodies

In primary hypothyroidism…

There is low hormone secretion by the thyroid gland, which constantly signals the pituitary to secrete TSH

In secondary Hypothyroidism..

Both TSH and T4 will be low (anterior pituitary problem)

Treatment of Hypothyroidism

Replacement of hormone therapy with Levothyroxine (T4-synthetic thyroid hormone)

MOA: converted to T3 in the body

Half life: 7 days

Surgical intervention if necessary

T3 is..

Active form of T4

Hyperthyroidism (Thyrotoxicosis)

Excessive secretion of T3 and T4 - Primary (thyroid) - Secondary (pituitary) - Tertiary (hypothalamus)

Most common cause of Hyperthyroidism

Grave's disease: an autoimmune stimulation of the thyroid gland

Other causes of Hyperthyroidism

- Thyroid adenoma - subacute thyroiditis - Toxic multinodular goiter (benign growth) - Excessive iodine ingestion (JOD-Basedow syndrome), -Excessive thyroid hormone replacement

Hyperthyroidism Risk Factors

``` Family Hx of graves Age >40 Women Caucasian Medications Excessive iodine intake Pregnancy ```

Grave's Disease

1. Autoimmune disorder 2. Excess levels of T3 + T4 3. Thyroid-stimulating antibodies (antibodies that stimulate the thyroid gland)

Grave's Disease Symptoms

- nervousness - Insomnia - Sensitivity to heat - Weight loss - Gland is usually enlarged and palpable - An audible bruit may be heard because high glandular blood flow - Atrial fibrillation - Myxedema - Exophthalmos

Exophthalmos

Wide-eyes stare associated with increased sympathetic tone and infiltration of the extraocular area with lymphocytes and mucopolysaccharides Periorbital edema and bulging of the eyes termed Grave's OPTHALMOPATHY Women are more often affected with Grave's Ophthalmopathy than men

Diagnosis of Graves Disease

- Low TSH - High T3 - High T4 - Antithyroglobulin - Antithyrotropin receptor antibody - Ultrasound with color-doppler evaluation - Radioactive iodine scanning and measurement of iodine uptake

In graves disease...

Radioactive iodine uptake is increased and the uptake is diffusely distributed over the entire glan

Treatment of Hyperthyroidism

Antithyroid hormone medication Propylthiouracil (PTU): blocks thyroid hormone synthesis conversion of T4 to T3 -Hepatotoxicity -Can be used in 1st trimester with caution Radioactive iodine treatment Surgery -Replacement thyroid hormone (levothyroxine) is needed for life

Thyrotoxic Crisis (Thyroid Storm)

Overwhelming release of thyroid hormones that exerts an intense stimulus on the metabolism This is life-threatening condition most commonly precipitated by surgery, trauma, or infection

Parathyroid gland

4 pea-sized glands within the thyroid tissue of the neck Produce and secrete parathyroid hormone (PTH) Controls calcium levels Promotes vitamin D production by the kidney

Hypoparathyroidism

A results of: insufficient PTH secretion and the resulting HYPOCALCEMIA ``` Muscle cramps Irritability Tetany Convulsions Trousseau's + Chvostek's ```

Hypoparathyroidism Treatment

Replace PTH Normalize serum Ca and Vitamin D levels If parathyroid has been removed: replacement treatments are life long

Hyperparathyroidism

``` Muscle weakness Poor concentration Neuropathies Hypertension Kidney stones Metabolic acidosis Osteopenia Pathological fractures Constipation Depression, Confusion, Cognitive defects ```

Symptoms of Hyperparathyroidism are caused by

Excessive secretion of PTH with resulting hypercalcemia and bone breakdown

Hyperparathyroidism Treatment

Reduce levels of calcium Diuretics Calcitonin Bisphosphonates Vitamin D Surgical intervention