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Treatment for Hypothyroidism in adults
Replacement therapy with thyroid hormones. In most cases, treatment must continue lifelong. has to be taken only once a day halflife 7-9 months Standard replacement regimen consists of T4 alone. Combined therapy with T4 and T3 is an option but there are studies of this giving no advantage over T4 alone.
Treatment for Hypothyroidism in infants
Replacement therapy with thyroid hormones. If treatment is initiated within a few days after birth, physical and mental development will be normal. If therapy is delayed beyond 3-4 weeks, some permanent retardation will be evident, although physical effects of thyroid deficiency will reverse. Treatment should continue for 3 years, then stopped for 4 weeks. If TSH rises, deficiency is permanent. * Objective is to determine if thyroid deficiency is permanent or transient.
Treatment for hyperthyroidism Grave's disease
Treatment is directed at decreasing the production of thyroid hormones. 3 methods: (1) Surgical removal of thyroid tissues, (2) destruction of thyroid tissue with radioactive iodine (3) suppression of thyroid hormone synthesis with anti-thyroid drugs. *Beta blockers and nonradioactive iodine may be used as adjunctive therapy. Beta blockers suppress tachycardia and nonradioactive iodine inhibits synthesis and release of thyroid hormones. * Treatment of Nodular Goiter (Plummer’s) is the same as for Grave’s
Treatment for hyperthyroidism Thyroid storm
High does of potassium iodine or strong iodine solution are given to suppress thyroid hormone release. PTU beta blocker cooling sedation glucocorticoids IV fluids
Pharmacologic treatment for thyroid disorders Indications
Hypothyroidism or Hyperthyroidism
Lab Tests for thyroid disorders
Serum TSH – Used primarily for screening and diagnosis of hypothyroidism; Serum T4 Test – Testing can measure either total T4 or free T4. Test can be used to monitor thyroid hormone replacement therapy, and to screen for thyroid dysfunction; Serum T3 Test – Measures total or free, useful or diagnosing hyperthyroidism because in this disorder, levels of T3 often rise sooner and to a greater extent than levels of T4. Can also be used to monitor thyroid hormone replacement therapy.
Thyroid disorders patient education T4
Instruct the client to take oral dosage on empty stomach, at least 30 minutes before breakfast; notify physician if symptoms of thyrotoxicosis develop; separate drugs that reduce T4 absorption by 1 -2 hours.
Thyroid disorders patient education PTU
Instruct patient to take PTU at regular intervals around the clock (usually q8h); inform patients about early signs of agranulocytosis (drop of concentration of agranulocytes like neutrophils, clinicla signs: sore throat, sudden fever, rigors), and instruct them to notify physician if these develop.
Levothyroxine (T4) use
Drug of choice for most patients who require thyroid hormone replacment.
Levothyroxine (T4) pharmacokinetics
Much of T4 is converted to T3 in the body.
Levothyroxine (T4) half-live and plasma level
Highly protein bound half-life is prolonged to about 7 days Well suited for lifelong therapy because of long half-life.
Levothyroxine (T4) therapeutic use
All forms of hypothyroidism – crentinism, myxedma coma, simple goiter, and primary hypothyroidism. Also used to treat hypothyroidism from insufficient TSH, insufficient TRH, and used to maintain proper levels of thyroid hormones following thyroid surgery, radiation, and treatment with anti-thyroid drugs. *SHOULD NO BE USED TO TREAT OBESITY.
Levothyroxine (T4) adverse effects
Rare; acute overdosage (thyrotoxicosis may result = tachycardia, angina, tremor, nervousness, insomnia, hyperthermia, heat intolerance, sweating )
Levothyroxine (T4) drug interactions
1. Reduced absorption by other drugs such as: Calcium supplements, Iron supplements, Aluminum-containing antacids, Colestipol, Cholestyramine 2. Accelerated metabolism by other drugs including: Dilantin, Tegretol, Zoloft 3. Warfarin: Enhances the effects of warfarin, so patient must reduce dosage of the anticoagulant. 4. Catecholamines: Thryoid hormones increase cardiac responsiveness to catecholamines (epinephrine, dopamine), thereby increasing the risk of catecholamine induced dysrhythmias.
Levothyroxine (T4) dosage, administration, general considerations
1. Administered orally and by IV. Oral doses should be given on empty stomach. IV dosage used for myxedma coma, and doses are 80% the size of oral doses. 2. Evaluation should show reversal of signs and symptoms of thyroid deficiency.
Liothyronine (T3) identical structure to that of thyroid derived T3 effects are identical to that of T4 difference to T4?
(1) has a shorter half-life and shorter duration of action (2) T3 has a more rapid onset (3) is more expensive than T4
Liothyronine (T3) evaluation
Dosage levels are adjusted on the basis of clinical evaluation and laboratory data. 2 Lab tests are useful – free serum T3 and serum TSH.
Liothyronine (T3) dosage and administration
Usually administered by mouth, although IV administration may be used. Dosage is about 80% of the dosage of T4.
Propylthiouracil (PTU) action
inhibits thyroid synthesis 1) inhibits thyroid hormone synthesis (2) suppress conversion of T4 to T3.
Propylthiouracil (PTU) Pharmacokinetics
PTU is rapidly absorbed following oral administration and therapeutic actions begin within 30 minutes. Half-life is about 75 minutes. *Drug can cross the placenta and can enter breast milk.
Propylthiouracil (PTU) therapeutic uses (4)
1. as sole form of therapy for grave’s disease 2. in combination with radiation therapy 3. before surgical removal of thyroid 4. patients experiencing thyrotoxic crisis. * Not all patients respond to PTU; those that do respond, prolonged treatment may be needed to normalize hormone production.
Propylthiouracil (PTU) adverse effects
(1) Agranulocytosis - Develops rapidly, discontinue PTU if this becomes present. (2) Hypothyroidism - When PTU is given in high doses, can convert patient from hyper to hypo state. (3) Pregnancy and lactation – PTU crosses placenta and has caused neonatal hypothyroidism and goiter. To minimize effect, dosage must be given as low as possible. Mum cannot breastfeed at all
Radioactive Iodine (I131) physical properties
Radioactive isotope of stable iodine emits a combination of beta particles and gamma rays. Half-life is 8 days.
Radioactive Iodine (I131) use in Grave's disease
destroy thyroid tissue in patients with hyperthyroidism. Objective is to produce clinical remission without causing complete destruction of the gland.
Radioactive Iodine (I131) advantages
(1) low cost, (2) patients are spared risks, discomfort, and expense of thyroid surgery, (3) death from treatment has never occurred, (4) no tissues other than thyroid are injured.
Radioactive Iodine (I131) disadvantages
(1) treatment is delayed, (2) significant incidence of delayed hypothyroidism
Radioactive Iodine (I131) who should be treated?
Patients over the age of 30 patients who have not responded adequately to anti-thyroid drugs or to subtotal thyroidectomy.
Radioactive Iodine (I131) who should not be treated?
Young children because higher incidence of delayed hypothyroidism, contraindicated in pregnancy and lactation. Exposure of the fetus to radioactive Iodine after the first trimester may damage the immature thyroid, and exposure to radiation at any point in fetal life carries a risk of generalized developmental harm.
Actions of thyroid hormones
basal metabolic rate stimulates use of energy stimulates the heart promotes growth and development
Signs of hypothyroidism
pale, puffy face cold, dry skin brittle hair, hair loss decreased heart rate lethargy and fatigue pregnancy: defects to child infant: decreased IQ
reasons for hypothyroidism
surgical removal of thyroid glands autoimmune disease insufficient iodine intake
Manifestation of hyperthyroidism
increased heart rate arythmias nervousness jittery insomnia rapid speech pattern increased voracious appetite
Thyroid storm symptoms
hyperthermia tachycardia agitation coma hypotension could lead to death
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