13 Hypothyroidism and Thyroiditis Flashcards
Absorption of LT4 occurs in (2) (ATA)
Jejunum
Ileum
Absorption of orally administered levothyroxine under optimum fasting conditions (ATA)
70-80%
For patients unable to take oral medications, the appropriate IV dose of LT4 is approximately what percent of the oral dose? (ATA)
75%
Increased / unchanged / decreased levothyroxine absorption (ATA):
Fiber
Decreased
Increased / unchanged / decreased levothyroxine absorption (ATA):
Soy products
Decreased
Increased / unchanged / decreased levothyroxine absorption (ATA):
Coffee
Decreased
Mechanism of coffee in decreasing levothyroxine absorption
Sequestration of LT4
Increased / unchanged / decreased levothyroxine absorption (ATA):
Grapefruit juice
Unchanged
Levothyroxine is recommended to be taken how many min before breakfast? (ATA)
60 min
Levothyroxine is recommended to be taken how many hours after dinner? (ATA)
3 hours
Where feasible, levothyroxine should be separated from other potentially interfering medications and supplements by how many hours? (ATA)
4 hours
Next step in management if levothyroxine dose requirements are much higher than expected? (ATA)
Evaluation for gastrointestinal disorders
Gastrointestinal disorders (3) to be considered in patients in whom levothyroxine dose requirements are much higher than expected (ATA)
H. pylori-related gastritis
Atrophic gastritis
Celiac disease
Reassessment of TSH should be done if patient is started on the ff drugs (8) (ATA)
Androgens
Carbamazepine
Estrogen
Phenobarbital
Phenytoin
Rifampin
Sertraline
TKIs
Increased / decreased / unchanged in hypothyroidism:
Total and LDL cholesterol
Increased
Increased / decreased / unchanged in hypothyroidism:
Lung volumes
Unchanged
Increased / decreased / unchanged in hypothyroidism:
Diffusing capacity of the lungs
Decreased
Increased / decreased / unchanged in hypothyroidism:
Maximal breathing capacity
Decreased
Increased / decreased / unchanged in hypothyroidism:
Appetite
Decreased
Weight gain in hypothyroidism does not usually exceed:
10% of body weight
Increased / decreased / unchanged in hypothyroidism:
Rate of intestinal absorption
Decreased
Increased / decreased / unchanged in hypothyroidism:
Total amount absorbed in the intestine
Normal or increased
Increase in risk of cholelithiasis in hypothyroid men
3.8x
Increased / decreased / unchanged in hypothyroidism:
Cerebral blood flow
Decreased
Increased / decreased / unchanged in hypothyroidism:
Cerebral oxygen consumption
Unchanged
Typical reduction in LDL in the treatment of hypothyroidism
5-10%
Acute hypothyroidism in the previously hyperthyroid patient seen after radioiodine therapy may be characterized by this symptom
Painful cramping of large muscle groups
Hallmark of cretinism
Retardation of mental development and growth
In patients with chronic renal insufficiency, these clinical findings (5) may suggest hypothyroidism
Anorexia
Torpor
Periorbital puffiness
Sallow complexion
Anemia
Risk of hypothyroidism following surgical lobectomy
20%
Risk factors for hypothyroidism following surgical lobectomy (2)
Iodine insufficiency
Anti-TPOAb
HLA associated with Hashimoto disease
HLA-DR3
Hodgkin disease survivors have ___ relative risk of developing hypothyroidism
17-fold
Hallmark of classic Hashimoto disease
Goiter
Ultrasound findings in Hashimoto disease (2)
Patchy heterogenous echotexture
Hypoechoic nodules with echogenic septations
In differentiating Hashimoto thyroitis from thyroid carcinoma, this clinical finding is pathognomonic of thyroid carcinoma
Compression of RLN with hoarseness
Table salt is enriched with this substance for iodine supplementation
Potassium iodide 0.01%
Pregnant patients should not receive iodide of this dose and duration
> 1 mg/day over >10 days
Soybean products induced goiter in infants by:
Enhancing fecal loss
Increased / decreased / unchanged:
Effect of cigarette smoking on development of hypothyroidism in those with underlying autoimmune thyroid disease
Decreased
Cassave meal contains this cyanogenic glycoside which may lead to the formation of thiocyanate
Linamarin
Reduction in T4 dose after treatment for 4 months of those with nonautoimmune primary hypothyroidism
50% for 6 weeks
Prevalence of hypothyroidism in patients treated with sunitinib after 37 weeks of follow-up
62%
Fraction of thyroid gland function that is independent of TSH
~10-15%
~10% of patients with RTH beta have this neuropsychologic illness
ADHD
Typical dose of levothyroxine
1.6-1.8 mcg/kg IBW
The long half life of T4 means that it is safe for a patient to take any missed doses of T4 for up to how long after missing tablets
1 week
Dessicated thyroid have how many fold higher ratios of T3 to T4 than the 1:15 value in normal human thyroglobulin
Twofold to threefold
The T3 content of 1 grain tablet Liotrix (T4 + liothyroinine) would be approximately equivalent to that obtained in what dose of levothyroxine
100 mcg
Initial recommended dose of levothyroxine in elderly px with heart disease
25 mcg/day
Recommended titration strategy of levothyroxine in elderly px with heart disease
Increase by 12.5 mcg at 2-3 month intervals
Pseudotumor cerebri as an adverse effect of LT4 therapy occurs in patients aged:
8-12 years old
Amount of diuresis in moderate to severe hypothyroidism
2-4 kg
Amiodarone can remain in tissues for up to how long
1 year
Dose of parenteral levothyroxine after loading dose in myxedema coma
80% of appropriate oral dose but not in excess of 1.4 mcg/kg IBW
OR
100 mcg daily
Initial serum T4 target for infants with congenital hypothyroidism
> 10 mcg/dL or >130 nmol/L
After what age is normal TSH an appropriate target of Lt4 therapy in congenital hypothyroidism
2 years
Adverse effects of maternal hypothyroidism to the offspring (3)
Fetal loss
Preterm delivery
Intellectual deficit
Normal to elevated serum FT4 and elevated TSH in a patient on LT4 therapy should make one suspect:
Poor adherence
Risk factors for progression from subclinical to overt hypothyroidism (2)
TSH >10
Positive antiTPOAb
Liothyronine improved cardiac indices in these patients (3)
Advanced CHF
After CABG
After surgery for congenital heart disease
Screening of hypothyroidism in older women
5-year intervals after 50 years
Neurodevelopmental effects on children of mother with isolated hypothyroxinemia (4)
Reduced IQ
Reduced cortical volume
Language delay
Autism
Mortality in myxedema coma
20% or higher
Bolus dose of LT4 in myxedema coma
500-800 mcg IV
Hydrocortisone dose in myxedema coma
5-10 mg/hr
Most common cause of repeated childhood infectious thyroiditis, particularly in the left lobe
Internal fistula extending from the pyriform sinus to the thyroid
More common in acute thyroiditis vs subacute thyroiditis:
Preceding upper respiratory infection
Acute thyroiditis
More common in acute thyroiditis vs subacute thyroiditis:
Fever
Acute thyroiditis
More common in acute thyroiditis vs subacute thyroiditis:
Painful thyroid swelling
Acute thyroiditis
More common in acute thyroiditis vs subacute thyroiditis:
Elevated WBC
Acute thyroiditis
More common in acute thyroiditis vs subacute thyroiditis:
Abnormal thyroid function
Subacute thyroiditis
More common in acute thyroiditis vs subacute thyroiditis:
Increased alkaline phosphatase, transaminases
Subacute thyroiditis
More common in acute thyroiditis vs subacute thyroiditis:
Lymphocytes, macrophages, polyps, giant cells on FNA
Subacute thyroiditis
More common in acute thyroiditis vs subacute thyroiditis:
Clinical response to glucocorticoid
Subacute thyroiditis
Treatment of Riedel thyroiditis
Tamoxifen 10-20 mg/day with or without corticosteroids