THYROID THERAPY
THYROID INTRODUCTION
n
Regulated by TSH
n
Uptake of Iodide from diet
n
Production of Thyroxine (not
active hormone)
n
Conversion to tri-iodothyronine
(active hormone)
–
conversion
in thyroid gland and periphery
Consequences of Low Iodide Diet
n
Decreased thyroxine production
n
Decreased blood levels
n
Increased release of TSH from
pituitary
n
Hypertrophy of Thyroid Gland
(goiter)
n
Increased Iodide trapping
n
Euthyroid
HYPOTHYROIDISM
n
ADULT (MYXEDEMA)
–
Symptoms include: drowsiness, slowed speech, decreased cardiac
output, skeletal muscle weakness
n
CHILDREN (CRETENISM)
–
Congenital malformation of thyroid
gland
–
If untreated: permanent mental retardation and failure to
grow
HYPERTHYROIDISM
n
Degrees of Severity
n
Most severe form: Thyrotoxicosis (thyroid storm)
n
Symptoms include opthalmalopathy,
high output cardiac failure
PHYSIOLOGIC ROLE OF THYROID HORMONE
n
Regulate growth and development
n
Regulate basal metabolic rate
n
Regulate cardiac output
n
Lipolytic activity on cholesterol
Use of Thyroid Replacement Therapy
n
Myxedema
n
Cretenism
Thyroid Replacement Medications
n
Levothyroxine - synthetic
thyroxine (T-4)
–
Minerals inhibit absorption
n
Liothyronine - synthetic T-3
(active hormone)
n
Thyroid Tablet - Dessicated
thyroid gland from cattle - mixed T3 and T4
–
Lot to lot variation
TREATMENT OF HYPERTHYROIDISM
n
Inhibitors of T3 and T4 Synthesis
–
Propylthiouracil (PTU) and
Methimazole
–
Contraindication: pregnancy,
breast feeding
–
70 to 80% complete remission and
discontinue
–
30% remain on therapy for life or
have radioactive therapy
TREATMENT OF HYPERTHYROIDISM
n
High concentration of Iodide
–
High concentration provides
negative feedback to thyroid gland for 72 hours
–
Pre-operative use to prepare
patient for surgery
–
Example: Super Saturated Potassium Iodide (SSKI)
n Also used as an expectorant
TREATMENT OF HYPERTHYROIDISM
n
RADIOACTIVE IODIDE (sodium iodide
I-131)
–
Onset of action: days to weeks
–
Remission: 2-3 months
–
25 to 33% of patients cured after
1 dose
–
Advantage: Avoid surgery
–
Disadvantage: Determine exact dose needed
–
Contraindication: pregnancy, children