Thyroid Disorders

Topic Discussion

Prepared by Todd S. Reese, MBAPharmD Candidate 2007

Midwestern UniversityMay, 2007

Learning Objectives

• Hypothyroidism• Hyperthyroidism• Thyroid Storm

The purpose of this presentation is to provide an overview of the following:

The Thyroid Gland• The thyroid gland is one of the

body’s endocrine glands found in the neck just below the Adam’s apple. The thyroid helps the body control energy consumption, protein production, and regulates the body’s sensitivity to other hormones.

• The chemical messengers produced by the thyroid are: – Thyroxine (T4)

– Triiodothyronine (T3)

– Calcitonin T3

T4 and T3

• Up to 80% of T4 is converted to T3 in the peripheral organs such as the Kidney, Liver, and Spleen

• Non-protein bound T3 is ten times more potent than T4 and is the principle chemical messenger used to:– Regulate the rate of metabolism– Affect the growth and rate of function of other

systems in the body.

How it works:

The Hypothalamus in the brain secretes TRH, which in turn stimulates the Pituitary to release TSH, which stimulates the Thyroid to release

T4 and T3.

HypothyroidismPrevalence: 2-17% in adult (♀>♂) populations

Common Symptoms:

•Fatigue

•Weight gain

•Cold intolerance

•Skin dryness

•Constipation

•Menstrual changes

•Cognitive impairment

•Depression

•Coarseness/loss of hair

•Joint pain

•Muscle cramps Diagnosed by ↑TSH and/or↓T4/T3 levels

HypothyroidismTreatment:Levothyroxine sodium

•Treatment of choice for routine management

•Multiple dosages available

•Titrated to individual needs

•Starting dose: 1.7 mcg/kg/Q24H

•50 mcg/Q24H

•Children may need up to 4 mcg/kg/Q24H

Clinical Counseling Pearl!

Take Levothyroxine in the morning on an empty stomach at least 30 minutes before food.

Clinical Counseling Pearl!

Take Levothyroxine in the morning on an empty stomach at least 30 minutes before food.

Hypothyroidism

Monitoring:

•Measure TSH levels in 30 days

•Goal is 0.5-3.0 mU/L

•If at goal level, recheck in one year

•If not at goal, increase dose by 20-50 mcg and recheck in 60-90 days

LevothyroxineDrugs which decrease

T4 absorption:

• Ferrous Sulfate• Aluminum Hydroxide• Cholestyramine• Colestipol• Sucralfate

Drugs which increase T4 metabolism:

• Phenobarbital• Phenytoin• Carbamazepine• Rifampin

Clinical Counseling Pearl!

Take Levothyroxine at least 4 hours apart from these medications.

Clinical Counseling Pearl!

Take Levothyroxine at least 4 hours apart from these medications.

HyperthyroidismPrevalence: 0.2-6% in adult populations

Common Symptoms:

•Fatigue

•Weight loss

•Heat intolerance

•Hyperhydrosis

•Nervousness

•Menstrual changes

•Insomnia

•Tremor

•Muscle Weakness

•Dyspnea

•Palpitations

Diagnosed by ↓ TSH and/or ↑T4/T3 levels

Causes of Hyperthyroidism:

•Grave’s disease

•Goiter or adenoma

•Excess thyroid hormone intake

•Pituitary tumor

•Iodine Exposure

Agents which can also decrease TSH:

•Glucocorticoids, Dopamine, Octreotide

HyperthyroidismTreatment:Propylthiouracil (PTU)

•Starting dose: 100-600 mg/Q24H

•Methimazole (MMI)

•Starting dose: 10-60 mg/Q24H

•Radioactive Iodine

•Surgery for goiters, adenomas, nodules

•Beta-Blockers as additional therapy

•Propranolol/Nadalol 80-160 mg/Q24HClinical Pearl!

PTU is the Drug of Choice in Pregnancy!

Clinical Pearl!

PTU is the Drug of Choice in Pregnancy!

Propylthiouracilversus Methimazole

PTU MMI

Response Time Dose-related, Hepatitis, Vasculitis

Dose-related,rare side effects

Compliance Worse Better

Cost $22 for 300mg/Q24H $62 for 30mg/Q24H

Thyroid StormThyroid Storm is a condition in which the thyroid becomes over active, producing too much T4 and T3.

Symptoms:• HIGH FEVER• Diaphoresis• Tachycardia• weight loss• Dehydration• Delirium• Coma• N/V/D

Clinical Pearl!

This is a MEDICAL EMERGENCY!

Clinical Pearl!

This is a MEDICAL EMERGENCY!

Causes of Thyroid StormPrecipitating factors for

Thyroid Storm include:

• Infection

• Trauma

• Surgery

• Radioactive Iodine treatment

• Withdrawal from antithyroid drugs

Treatment of Thyroid Storm

Questions? www.thyroid.org

Topic Discussion

Prepared by Todd S. Reese, MBAPharmD Candidate 2007

Midwestern University

May, 2007