EXAM 5 - Thyroid Disease

human chorionic gonadotropin (hCG) secreting tumor

hCG can bind to TSH receptors in the thyroid gland and increase production of the thyroid hormones - secondary hyperthyroidism

The classic pattern of changes in thyroid function in patients with subacute and painless thyroiditis

hyperthyroidism, followed by hypothyroidism, and then recovery (no recovery in hashimotos)

most common cause of secondary hyperthyroidism

pituitary tumor which synthesizes TSH

Infectious thyroiditis is caused by what?

Staphylococcus and Streptococcus

Treatment of secondary Hypothyroidism, what is essential to check first

-it is essential to check for co-existing adrenal insufficiency before treatment of hypothyroidism

radioactive iodine treatment for graves disease

- 10% incidence of hypothyroidism at 1 year - 55-75% incidence of hypothyroidism at 10 years - AVOID in children and pregnancy

surgery for graves disease treatment

- large goiters no amendable to RAI - compressive symtoms - children and pregnant (might be the only safe option) - 50-60% incidence of hypothyroidism

Treatment of myxedema coma includes what generally

1. thyroid replacement 2. glucocorticoids 3. supportive measures 4. Appropriate management of coexisting problems (infection)

Myxedema Coma

A special condition called myxedema coma is defined as severe hypothyroidism leading to decreased mental status, hypothermia, hypotension, bradycardia, hyponatremia, hypoglycemia, and hypoventilation.

what is graves disease

Autoimmune disorder resulting from TSH-receptor antibodies which stimulate thyroid gland growth and thyroid hormone synthesis and release

Treatment for graves disease symptoms

Beta blockers

treatment for Thyroid Storm

Beta blockers (propranolol) should be used, along with a thionamide, and glucocorticoids

Diagnosis of Thyroid Disease

Diagnosis of the different forms of thyroid disease are based on the TSH level, free T3 level, and free T4 level.

graves disease is seen in who? What about toxic nodular goiter?

Grave's disease is seen most often in younger women, while toxic nodular goiter is more common in older women.

what is the most common cause of hyperthyroidism

Grave's disease is the most common cause of hyperthyroidism

clinical manifestations of graves disease to consider

Grave's disease, the most common cause of hyperthyroidism, causes unique problems that are not related to the high serum thyroid hormone concentration. These include ○ Graves' ophthalmopathy--proptosis-exophthalmos ○ Infiltrative dermopathy--localized or pretibial myxedema

Hashimoto's thyroiditis causes hyper or hypothyroidism?

Hashimoto's thyroiditis at first causes hyperthyroidism then hypothyrd.

incidence of hyperthyroidism

Hyperthyroidism is more common in women than in men (5:1 ratio)

Labs with Hashimoto's thyroiditis

Hypothyroidism antiTOP antibodies (90%) anti thyroglobulin antibodies (20-50%) acute hyperthyroidism (5%)

Signs of hyperthyroidism

Irritability, hyperactivity, high blood sugar, low serum cholesterol

autoimmune Hashimoto's thyroiditis is caused by what>

It is caused by cell and antibody mediated destruction of the thyroid tissue. It may begin as hyperthyroidism, but progresses to permanent hypothyroidism.

What is Thyroid Storm precipitated by

It is often precipitated by an acute event such as thyroid or non-thyroid surgery, trauma, infection, an acute iodine load

Myxedema Coma is precipitated by what?

It is precipitated in patients with hypothyroidism who develop infection, myocardial infarction, cold exposure, or the administration of sedative drugs, especially opioids.

treatment with Hashimoto's thyroiditis

Levothyroxine if hypothyroid Triiodothyronine for myxedema coma thyroid suppression (Levothyroxine) to decrease gioter size surgery for compression or pain

Goiters with hyperthyroidism

Most patients with Grave's disease have a diffuse goiter, but so do patients with other, less common causes of hyperthyroidism such as painless thyroiditis and TSH secreting pituitary adenomas

patients in Thyroid Storm need to be treated where?

Supportive therapy in an ICU is warranted

when T3-T4 combination therapy, what should the ratios be

T3-T4 13:1 to 16:1

TSH level, free T3 level, and free T4 level in primary hypothyroidism

TSH - high fT4 - low fT3 - low

TSH level, free T3 level, and free T4 level in secondary hyperthyroidism

TSH - high/normal fT4 - high fT3 - high

TSH level, free T3 level, and free T4 level in primary hyperthyroidism

TSH - low fT4 - high fT3 - high

TSH level, free T3 level, and free T4 level in secondary hypothyroidism

TSH - low fT4 - low fT3 - low

TSH level, free T3 level, and free T4 level in T3 toxicosis

TSH - low fT4 - normal fT3 -high

TSH level, free T3 level, and free T4 level in euthyroidism

TSH - normal fT4 - normal fT3 - normal

TSH level, free T3 level, and free T4 level in sick euthyroid syndrome

TSH - normal/low fT4 - low fT3 - low

Thyroiditis includes what?

They include conditions that cause acute illness with severe thyroid pain and conditions in which there in no clinically evident inflammation and the illness is manifested primarily by thyroid dysfunction or goiter.

Treatment for graves disease to inhibit the synthesis of thyroid hormones

Thionamide drugs include methimazole and propylthiouracil. - inhibit the synthesis of thyroid hormones by blocking the oxidation of iodine in the thyroid gland - may reestablish euthyroidism in 6-8 weeks - 40-60% incidence of disease remission - 20% incidence of allergy (rash) - 0.5% risk of fatal agranulocytosis

Thyroiditis

This term encompasses a diverse group of disorders characterized by some form of thyroid inflammation

Thyroid Storm

Thyroid Storm is a rare, but life-threatening condition characterized by severe or exaggerated clinical manifestations of thyrotoxicosis

Do we need thyroid hormones constantly available?

Thyroid hormones must constantly be available to perform these functions

what can we do to maintain the availability of Thyroid hormone?

To maintain their availability, there are large stores of thyroid hormone in the circulation and in the thyroid gland

Treatment of Hypothyroidism

Treatment of choice is synthetic thyroxine (levothyroxine). For the vast majority of patients, levothyroxine alone is sufficient.

Hypothyroidism symptoms and signs variance

Whether hypothyroidism results from hypothalamic-pituitary disease or primary thyroid disease, symptoms and signs of the disease vary in relation to the magnitude of the thyroid hormone deficiency and the acuteness with which the deficiency develops.

Hyperthyroidism lab workup

Work-up with TSH, T3, T4 levels

levothyroxine doses in young healthy vs older/coronary heart disease

Younger, healthy patients can begin with the full anticipated dose (1.6 mcg/kg/day) of levothyroxine but patients who are older with coronary heart disease should be started on a lower dose (25-50 mcg/day) and titrated upward slowly.

Painless thyroiditis is often what>

autoimmune mediated and can also occur after exposure to certain drugs.

Hashimoto's thyroiditis

an autoimmune disease in which the body's own antibodies attack and destroy the cells of the thyroid gland - most common cause of goiter and hypothyroidism in the US

The clinical manifestations of hyperthyroidism in relation to the disease?

are largely independent of its cause--however, the disorder that causes hyperthyroidism may have other effects.

Thyroid hormone biosynthesis and secretion regualtion

are maintained within narrow limits by a regulatory mechanism that is very sensitive to small changes in circulating hormone concentrations

most common cause of hypothyroidism

autoimmune Hashimoto's thyroiditis

Oxygen consumption and carbon dioxide production with hyperthyroidism

both increase in hyperthyroidism, resulting in hypoxia and hypercapnia. This stimulates ventilation causing the feeling of dyspnea

tertiary hypothyroidism

caused by thyrotropin-releasing hormone deficiency. Less than 1% of patients have these forms of central hypothyroidism

Treatment of myxedema coma - thyroid replacement

combine therapy with T4 and T3. They are given intravenously as slow bolus (initial dose 200-400 mcg T4 followed by IV doses of 50-100 mcg per day until patient can take orally along with IV dose T3 (5-20 mcg) every eight hours until clinical improvement occurs

Role of Thyroid hormones

critical determinants of brain and somatic development in infants and of metabolic activity in adults--they affect the function of virtually every organ system

Treatment of secondary hyperthyroidism

includes removal of the pituitary tumor which synthesizes TSH (most common secondary cause, but rare) or removal of the human chorionic gonadotropin (hCG) secreting tumor

Euthyroid-sick syndrome

is a physiologic adaptation to chronic disease/starvation and should not be treated with levothyroxine.

weight loss in hyperthyroidism

is typical and due to an increase in the metabolic rate

aim of treatment in Hypothyroidism

keep the TSH level within normal range

Infiltrative dermopathy

localized or pretibial myxedema

T3-T4 combination therapy

may improve symptoms in selected patients with Hypothyroidism (after thyroidectomy or ablative therapy with radioiodine

Treatment of myxedema coma - supportive measures

mechanical ventilation, IV fluids, electrolyte replacement, glucose, correction of hypothermia

Graves' ophthalmopathy

proptosis-exophthalmos

The treatment or correction of central hypothyroidism

synthetic levothyroxine ○ Weight-based dose of 1.6 mcg/kg is begun

Secondary hypothyroidism

that caused by TSH deficiency

Thyroiditis that presents with thyroid pain and tenderness

typically caused by subacute thyroiditis and less frequently, by infectious or traumatic etiologies.

Treatment of myxedema coma - glucocorticoids

until the possibility of coexisting adrenal insufficiency has been excluded. Hydrocortisone 100 mg IV q 8 hours

Patients treated with levothyroxine who have unsuspected and untreated secondary adrenal insufficiency

will precipitate an acute adrenal crisis ● Adrenal insufficiency needs to be treated first, if present

There are two forms of Hashimoto's thyroiditis

○ Goiter ○ Atrophic ○ They differ in the extent of lymphocytic infiltration fibrosis, and thyroid follicular cell hyperplasia

The classical symptoms of thyroid storm include

○ Tachycardia ○ Hyperpyrexia ○ CNS dysfunction (agitation, delirium psychosis, stupor, or coma) ○ GI symptoms (nausea, vomiting, abdominal pain)

There are two biologically active thyroid hormones

○ Thyroxine, T4 ○ 3,5,3'-triiodothyronine, T3