Thyroid and Parathyroid Drug Therapy

Evaluate for therapeutic response: of cinacalcet

Serum calcium trending toward normal levels 9 to 10 mg/dL Decreasing symptoms of hypercalcemia

Side effects/Adverse effects for levothyroxine

Side effects: GI upset (rare) Adverse effects: Hyperthyroidism from drug therapy Thyroid storm Long term: osteoporosis

The nurse teaches the patient taking methimazole to report which symptom to the primary health care provider immediately?

Sore throat A serious adverse effect of antithyroid medication is agranulocytosis. Sore throat and fever should be reported

Pharmacokinetics Calcitriol

Absorption: readily absorbed from GI tract Distribution: 99% protein bound Metabolism: in the liver by the cytochrome P450 family of enzymes Excretion: biliary, hepatic recirculation, fecal

Cinacalcet would be used with caution in patients with which condition?

History of seizure disorder

Which condition is an absolute contraindication to the administration of thyroid replacement preparations?

Hyperthyroidism Contraindications to thyroid preparations include known drug allergy, recent myocardial infarction, adrenal insufficiency, and hyperthyroidism

Drug Interaction cinacalcet

Increased toxicity with many drugs due to CYP2D metabolism pathway. Careful review of medications before dosing is a priority.

Evaluation of therapeutic effects: levothyroxine

Initial symptoms of hypothyroidism resolving No evidence of cardiac symptoms indicating thyroid excess T3, T4, TSH normalizing

Absolute Contraindications: Cinacalcet

Known drug allergy Hypocalcemia Renal disease without dialysis (may cause hypocalcemia)

Lab of cinacalcet

May cause false negative tuberculosis skin test

A patient has a new prescription for propylthiouracil. Which instructions are important in relation to drug therapy?

"Stopping the drug suddenly is not recommended." Take antithyroid drugs with meals." "This drug should not take amiodarone with the prescribed drug." "Report a slow heart rate of below 60 beats per minute.

Which should be included in the discharge instructions for a patient taking levothyroxine?

"You will need to have lab work done periodically."

In which time frame should patients expect full therapeutic response from levothyroxine?

3 to 4 weeks

Methimazole Pharmacokinetics

Absorption: RapidDistribution: Protein Bound: 0%Metabolism: LiverExcretion: Kidney, excreted in breast milk, crosses placenta

Propylthiouracil Pharmacokinetics

Absorption: Readily absorbed from GI tractDistribution: Protein Bound: 75% to 80%Metabolism: Liver

Pharmacokinetics levothyroxine

Absorption: majority of dose absorbed from small intestine Distribution: all tissues; 99% is protein bound Metabolism: primary metabolism by the liver with some direct excretion into the bile Excretion: 80% kidneys, 20% fecal

Pharmacokinetics Cinacalcet

Absorption: rapidly absorbed from the intestines following oral administration; rate increased with high-fat meals Distribution: 97% protein bound Metabolism: in the liver by various hepatic enzyme systems Excretion: inactive metabolites are excreted primarily by the kidneys

Patients taking levothyroxine in combination with the following drugs need to be monitored closely for the reasons described:

Adrenergic drugs such as epinephrine: increases sympathetic response (heart rate, blood pressure, possible coronary insufficiency); cardiac medications may need to be adjusted. Oral anticoagulant drugs such as warfarin: increases anticoagulant effects due to displacement from protein-binding site. Warfarin dosage may need to be adjusted. Antidiabetic drugs such as insulin or metformin: increases in blood glucose levels; insulin and noninsulin dosage may need to be increased.

Methimazole:dosage

Adult: P0 15 to 60 mg/day

Propylthiouracil:dosage

Adult: PO 300 to 900 mg/day

Drug dosage levothyroxine

Adult: adjusted by age and responseOral (PO) Initially: 25 to 50 mcg/dayMaintenance: 50 to 200 mcg/day In myxedema coma: Intravenous (IV) Initially: 300-500 mcg/kg/day; then 50 to 00 mcg/day until able to give by oral route

Absolute contraindications: Calcitriol

Allergy to drug Hyperphosphatemia Hypercalcemia Vitamin D toxicity

A patient with diabetes is prescribed levothyroxine for hypothyroidism. Which action from the health care provider should the nurse anticipate occurring for this patient?

An increase in the patient's dose of insulin

Clinical manifestations:Hyperthyroidism (including Grave disease and thyrotoxicosis)

Anxiety, nervousness Weight loss Elevated heart rate with palpitations Elevated blood pressure Exophthalmia

Before administering levothyroxine, the nurse will:

Assess baseline vital signs, paying specific attention to cardiac dysrhythmias due to risk with drug therapy Review laboratory test results including T3, T4, TSH

Before administering antithyroid drugs, the nurse will:

Assess baseline weight and pulse Review laboratory test results:T3, T4, TSHLiver functions (aspartate aminotransferase [AST], alanine aminotransferase [ALT], gamma-glutamyl transferase [GGT], Alk Phos)

Which self-assessment technique would the nurse include when teaching a patient about using methimazole for hyperthyroidism?

Assessing pulse rate Hyperthyroidism can cause increased heart rate, and medications to treat hyperthyroidism can cause decreased heart rate. Patients should be taught to assess their pulse rate; they should also be taught to report significant changes.

Absolute contraindication:Antithyroid drugs

Known drug allergy Use caution with: Pregnancy: antithyroid drugs FDA pregnancy category D (Note: The FDA recommends propylthiouracil during the first trimester and methimazole for the remainder of pregnancy.) Persons experience thyroid crisis, which can be life threatening

Which drug would the nurse anticipate being prescribed to Ms. Weston after she is diagnosed with hypothyroidism?

Levothyroxine

A patient receiving calcitriol for low blood calcium is prescribed verapamil for hypertension. Which action would the nurse take?

Hold the verapamil and notify the health care provider. The patient is receiving calcitriol for low calcium blood levels, while verapamil is a calcium channel blocker. The additional drug, verapamil, would be held until further clarification is received.

adverse effects of calcitriol

Hypercalcemia, hypercalciuria Dehydration Ataxia Hypertension Hyperthermia Erythema multiforme Vitamin D toxicity

Which time of day is best for taking a thyroid replacement drug?

Before breakfast Patients should be encouraged to take thyroid replacement drugs before breakfast because food hampers absorption rate.

Pre-Administration Assessment Cinacalcet

Before giving cinacalcet the nurse will review labs Serum electrolyte levels; specifically, calcium, phosphate, ionized calcium Note: Hyperparathyroidism with high calcium levels is usually caused by a parathyroid tumor. Drug use for hyperparathyroidism is limited.

Which description regarding the action of methimazole, a drug prescribed for hyperthyroidism, is accurate?

Blocks thyroid hormone synthesis

Which phrase describes the action of propylthiouracil (PTU) when prescribed for hyperthyroidism?

Blocks thyroxine conversion to triiodothyronine (T3) in peripheral tissues

adverse effects of cinacalcet

Bone fractures Heart failure Seizures Arrhythmia Angioedema GI bleeding

Monitor patient during therapy: of cinacalcet

Bowel elimination patterns, weight changes Urinary elimination and hydration status Evidence of dizziness, weakness

Monitor labs during therapy: of cinacalcet

Calcium Phosphate Ionized calcium Liver function tests

Hyperparathyroidism Drug Therapy

Cinacalcet (prototype)

Clinical Manifestations Overview of Hyperparathyroidism

Clinical manifestations are often classified as: "Stones": referring to kidney stones, which can ultimately lead to urinary obstruction and possible renal failure "Bones": referring to bone-related complications including osteoporosis or osteomalacia "Thrones": referring to frequent use of the bathroom for frequent urination (polyuria) and constipation "Psychiatric overtones": referring to central nervous system symptoms of fatigue, depression, memory loss, delirium, and psychosis Muscle weakness is also commonly seen

Clinical Manifestations Hypoparathyroidism

Convulsions Arrhythmias Tetany Numbness in the hands and feet and around the mouth

Which phrase describes the goal of cinacalcet drug therapy?

Decrease and normalize calcium levels.

Which phrase describes the action of cinacalcet when prescribed to balance calcium levels in the body?

Decreases PTH by increasing calcium receptor sensitivity in the body

Patient/family teaching includes the following points: levothyroxine

Demonstrate taking pulse. Stress the goals of therapy, that full therapeutic effect may take 3 to 4 weeks, that replacement is not a cure but controls symptoms. Advise to take as prescribed. Stopping the drug will cause symptoms to return. Instruct to keep follow-up visits to monitor thyroid function. Keep the drug container protected from light. Take the drug at same time each day, preferably before breakfast. Food and certain drugs will hamper absorption rate. Avoid or limit foods that inhibit thyroid secretion (strawberries, peaches, pears cabbage, turnips, spinach, kale, brussels sprouts, cauliflower, radishes, and peas). Suggest using Medic Alert identification card or bracelet with health condition and drugs used. Report signs of hyperthyroidism (tachycardia, angina, tremors, nervousness, insomnia, hyperthermia, heat intolerance, sweating) because levothyroxine overdose may cause thyrotoxicosis.

Evaluate for therapeutic response: of calcitriol

Diminishing symptoms of hypocalcemia Normalizing calcium values to 9 to 11 mg/day

Which phrase indicates therapeutic effectiveness of cinacalcet prescribed for hyperparathyroidism?

Down trending of calcium blood levels toward normal

Interactions antithyroid drugs

Drug Interactions Increases action and blood levels of digoxin Increases blood thinning action of oral anticoagulant Decreases effectiveness of amiodarone, potassium iodine Effect on Laboratory Values Increases PT; AST, ALT, Alk Phos

Absolute Contraindications levothyroxine

Drug allergy Recent myocardial infarction (MI) Adrenal insufficiency Hyperthyroidism (thyrotoxicosis) ***Not to be used for weight loss

Intervention:Hypothyroidism

Drug replacement therapy: levothyroxine (prototype)

Intervention Hypoparathyroidism

Drug therapy with calcitriol (vitamin D3), the prototype drug for this lesson. In addition, calcium carbonate (citrate) or calcium chloride (IV) can be used.

Lab values calcitriol

Elevation in AST/ALT, blood urea nitrogen, creatinine

IV Administration: levothyroxine

Follow recommended reconstitution instructions. Only compatible with normal saline. Not compatible with other solutions or drug.

Side effects: antithyroid

Frequent: Urticaria, rash, pruritus Nausea Increase skin pigmentation Headache, paresthesia Occasional: drowsiness

Which action facilitates cinacalcet absorption?

Giving with meals

A nurse is preparing to administer levothyroxine. Which finding would require further assessment?

Heart rate of 110 beats/min

Adverse effects of anti thyroid

Hepatitis: observe for jaundice Bone marrow depression: agranulocytosis. May develop infection with symptoms of sore throat, fever, malaise. Thrombocytopenia (may occur up to 4 months after start of therapy)

Monitoring for Safe Administration antithyroid

Monitor heart rate and weight daily during therapy Observe for jaundice: the presence of jaundice is an indication of hepatitis, a serious adverse effect Monitor laboratory values (T3, T4, TSH) for therapeutic response Monitor lab values for adverse response: Increased LFTs, bilirubin indicates hepatotoxicity. Decreased white blood cells (leukopenia) indicate altered immune functioning. Decreased platelets indicate increased bleeding risk. If patient taking digoxin, monitor digoxin blood levels; may need reduced dose. If patient taking anticoagulants, monitor PT, International Normalized Ratio; may need reduced dose.

In the past parathyroid hormone drugs did not exist. However, the Food and Drug Administration (FDA) recently granted orphan drug status to

Natpara, a recombinant human PTH. It is used to manage hypocalcemia only after vitamin D and calcium supplementation have been tried. Because of the risks associated with the drug, it is only available through a restricted program called the Natpara REMS (Risk Evaluation and Mitigation Strategy) Program (Shire, 2019).

Which side effect commonly occurs with cinacalcet drug therapy?

Nausea and vomiting

side effects of cinacalcet

Nausea, vomiting, diarrhea Paresthesia, myalgia, arthralgia Anorexia Dizziness Rash, urticaria

Clinical manifestations:Hypothyroidism

Nonpitting edema of the lower legs (severe, uncontrolled hypothyroidism is known as myxedema) Weakness Fatigue Cold intolerance Weight gain

Which value indicates the effectiveness of levothyroxine?

Normal thyroid stimulating hormone (TSH) and T4

An older female patient admitted to the hospital with fatigue, weight loss, and lack of appetite states that she has not been taking the prescribed calcitriol. Her serum calcium level 8.3 mg/day. Which focused assessment should the nurse complete?

Observe for hand spasms when taking the blood pressure.

Use caution with: levothyroxine

Older adults During pregnancy, breastfeeding Persons with:Swallowing disordersDiabetes mellitusAngina pectorisHypertension or cardiovascular disease Note:Thyroid hormone sensitizes the heart to catecholamines (epinephrine, dopamine, dobutamine) and may produce dysrhythmias.

Pharmacodynamic Profile levothyroxine

Onset of oral dose: 3 to 5 daysOnset of IV dose: 6 to 8 hoursPeak: 2 to 4 hoursDuration: unknown

Pharmacodynamic Profile Calcitriol

Onset: 30 minutes to 1 hour after oral administrationPeak: 3 to 6 hoursHalf-life: 5 to 8 hoursDuration: 3 to 5 days

Pharmacodynamic Profile Cinacalcet

Onset: 30 minutes to 1 hour following oral administrationPeak: within 6 hoursHalf-life: 30 to 40 hoursDuration: unknown

drug dosage of cinacalcet

Oral dose: 30 mg twice daily; calibrating upward to max dose of 90 mg 2 to 3 times daily to achieve desired lab values

drug dosing of calcitriol

Oral dosing: 0.25 mcg/day Intravenous dosing: 1 to 2 mcg 3x weekly

Pharmacodynamics Methimazole (prototype drug)

PO: Onset: 12 to 18 hoursPeak: 1 to 2 hoursDuration: 36 to 72 hoursHalf-life: 4 to 6 hours

Pharmacodynamics Propylthiouracil

PO: Onset: up to 3 weeksPeak: 6 to 8 weeksDuration: 1 week to 1 month

Use with caution: calcitriol

Persons at risk for seizures Persons with cardiovascular disease Pregnancy (unless benefit outweighs fetal risk), breastfeeding

Drug interactions: calcitriol

Potentiates hypercalcemia when used with thiazide diuretic or calcium supplements Potentiates cardiac dysrhythmia when used with digoxin or verapamil Lipid lowering drugs decrease calcitriol absorption and effectiveness

Use with caution: cinacalcet

Pregnancy, breastfeeding Children Seizure disorders Cardiovascular disease Moderate to severe hepatic impairment

By which action does calcitriol treat hypoparathyroidism?

Promotes calcium absorption from the intestines and reabsorption from the kidney

A patient newly diagnosed with hyperthyroidism is pregnant. Which antithyroid drug should be used during first trimester

Propylthiouracil (PTU) PTU is used for hyperthyroidism, particularly in the first trimester of pregnancy.

safe administration of calcitriol

Store medication in a light resistant container Monitor serum calcium level Assess for adverse effects of hypocalcemia (tetany) Test for Trousseau sign: Inflating blood pressure cuff above systolic BP will cause carpal spasm. Test for Chvostek sign: Tapping in front of ear on facial nerve produces a facial spasm. Severe hypocalcemia may cause seizures. Anticipate using calcium glucoronate IV for rapid replacement.

Patient/family teaching includes the following: calcitriol

Stress goals of therapy. Advise to take drug as prescribed. Monitor weight weekly. Advise to keep follow-up visits to monitor drug response.

Patient/family teaching includes the following points:

Stress rationale for drug therapy Take drug as prescribed Take with food for better absorption, but limit high-fat foods due to interaction with drug Do not crush, chew, or dissolve tablet Instruct patient to keep follow-up appointment to note drug response Report immediately to the health care provider: vomiting, diarrhea, cramping, seizures, muscle pain including tetany

Patient/family teaching includes the following points: antithyroid

Stress rationale for therapy; remind that response to therapy may take several months, and that drug therapy is not a cure but used to manage symptoms. Advise to take as prescribed. Stopping antithyroid drug could bring on thyroid crisis. Instruct to take the medication with a meal and limit intake of iodine rich foods like seafood, seaweed, and iodized salt, which will decrease drug effectiveness. Tell the health care provider about use of over the counter drugs that may interfere with absorption or compromise effectiveness. Take pulse daily. Demonstrate how to take pulse. Pulse rate should be decreasing toward a normal rate. Report pulse rate less than 60 beats/min. Teach patient the side effects of antithyroid drug and how to manage. Contact the health care provider for yellowing of skin/eyes, unusual bleeding/bruising, or fever. Report signs of hypothyroidism (fatigue, weight gain, hair loss); excessive drug therapy may cause hypothyroidism.

Hyperparathyroidism Intervention

Surgery to remove tumor

A patient has a new prescription for calcitriol. Which pre-administration assessment would the nurse complete?

Survey the current serum calcium level.

A female patient who has been taking levothyroxine comes for a follow-up visit. The nurse notices that the patient's hands are shaking slightly and she is having difficulty sitting quietly. Which action would the nurse take first?

Take her vital signs and compare to previous reading. The first nursing action would be to take the vital signs and compare to previous readings. Changes in vital signs over time, particularly elevated blood pressure and heart rate, would further validate hyperthyroidism, a side effect of levothyroxine.

PO Administration: levothyroxine

Take with plenty of water. Give levothyroxine at a consistent time each day (protocols may dictate specific time). Administer about 4 hours apart from drugs that interfere with absorption.

food interaction cinacalcet

Taking drug with a high fat meal will increase effect

Which rationale would the nurse provide for limiting high-fat foods in a patient prescribed cinacalcet for hyperparathyroidism?

The drug effects are increased with high-fat foods.

Antithyroid Drugs therapeutic uses

The goal of drug therapy is to promote thyroid hormone homeostasis. Therapeutic uses include treatment of hyperthyroidism and preparation for surgery (thyroidectomy).

Therapeutic Uses levothyroxine

The goal of drug therapy with levothyroxine is to restore thyroid homeostasis. It is used as thyroid hormone replacement to treat myxedema coma, congenital hypothyroidism, simple goiter, and for TSH suppression.

Other drugs interfere with the protein binding of levothyroxine and reduce drug effectiveness by increasing its metabolism and excretion.

These include phenytoin, phenobarbital (for seizures), sertraline, and estrogen.

Mechanism of Action of levothyroxine

This drug mimics thyroid hormone activity by regulating basal metabolic rate, lipid and carbohydrate metabolism, brain development and function, maintaining cardiac and skeletal muscle function, and stimulating respiratory uptake of oxygen.

Before administering calcitriol, the nurse will assess for signs of hypocalcemia:

Twitching of mouth Tinging and numbness of fingers carpopedal spasm Larynx spasm Review laboratory test results: PTH level Serum calcium level Vitamin D level

Which action enhances the effectiveness of levothyroxine for the patient with hypothyroidism?

Using levothyroxine at a consistent time each day

Monitoring during therapy: levothyroxine

Vital signs, especially blood pressure (BP) and pulse. Report pulse rate > 100 in adult Weight daily or weekly as needed Heights and grow rate of infants Side effects, adverse effects Intervene per protocols, document and report finding to the health care provider

side effects if calcitriol

Weakness, headache, drowsiness Nausea, vomiting, constipation, weight loss Dry mouth, increased thirst Frequent urination; urinary tract infection

Evaluation of therapeutic effects: antithyroid

Weight gain, normalizing of heart rate and BP T4 normalizing

Hyperthyroidism (including Grave disease and thyrotoxicosis) is

an increase in circulating T4 and triiodothyronine (T3) levels, which usually results from an overactive thyroid gland or excessive output of thyroid hormones from one or more thyroid nodules. It may be mild with few symptoms, or severe, as in thyroid storm (thyrotoxicosis) in which death may occur from vascular collapse.

Calcitriol is classified as a calcium regulator. It acts on

binding sites in intestinal mucosa, and possibly on the kidney and parathyroid glands. Calcitriol increases blood calcium levels by increasing intestinal absorption of dietary calcium, stimulating release of calcium from the bones, and increasing renal tubular reabsorption of calcium.

for use of levothyroxine Use consistent brand of drug; do not interchange due to

bioequivalence issues between manufacturers.

Calcitriol The goal of drug therapy is to increase

calcium levels and restore blood calcium balance. Calcium may also be given by the intravenous route in an emergent situation, such as to treat seizures. Therapeutic Use: Hypocalcemia, renal failure, and dialysis

Some drugs interfere with levothyroxine absorption. These include

cholestyramine, colestipol, aluminum and magnesium antacids, H2 receptor blockers, proton pump inhibitors, sucralfate, calcium supplements, and magnesium.

The goal of drug therapy with cinacalcet is to

decrease calcium levels and restore calcium balance. Therapeutic use: hyperparathyroidism, hypercalcemia

Thyroid storm is a severe form of

hyperthyroidism and manifests in agitation; high temperature; rapid, irregular heart beat; and nausea and vomiting. Note: Thyroid storm requires emergency intervention.

An enlarged thyroid gland, or goiter, develops in some people with

hyperthyroidism due to lack of iodine in the diet or overproduction of thyroid stimulating hormone (TSH).

Mechanism(s) of Action Methimazole

inhibits synthesis of thyroid hormone by decreasing iodine, whereas propylthiouracil blocks conversion of thyroxine to triiodothyronine (T3) in peripheral tissue.

Hypothyroidism

is associated with deficiency in thyroid hormones (T3, T4). There are several causes, including Hashimoto thyroiditis (an autoimmune inflammation), radioiodine therapy, excess intake of antithyroid drugs, or thyroidectomy. It can also occur during in the neonatal period.

Intervention: Hyperthyroidism can be treated with

methimazole or propylthiouracil. These drugs decrease the production of thyroid hormones while a patient waits for a subtotal thyroidectomy or radioactive iodine therapy.

Hypoparathyroidism is a deficiency in

parathyroid hormone (PTH). The major function of PTH is to regulate the level of calcium in the body. It also controls the level of phosphorus and has a role in the production of the active form of vitamin D. All of these activities are required to maintain calcium balance. It can be caused by an autoimmune process; vitamin D deficiency; low magnesium levels; and drugs such as prednisone, phenobarbital, and bisphosphonate (for osteoporosis). During thyroid surgery, a parathyroid gland may be removed or damaged; this can be a cause of low PTH, low calcium, and high phosphorous levels.

Primary hyperparathyroidism, or high calcium and low phosphorous, is usually caused by a

tumor in one of the parathyroid glands. However, it can also be related to Paget disease, osteoporosis, cancer with metastasis to bones, chronic kidney disease, and use of thiazide medications.