CC Sept 2017 Subclinical hypothyroidism in adults

echoecho's version from 2017-12-03 07:05


Question Answer
The levels of T3 and T4 is regulated by what hormone secreted by the pituitary gland?TSH
What happens if there are low levels of thyroid hormones? release of TSH
What happens if there are elevated levels of thyroid hormonessuppression of TSH
Why is measurement of TSH the best test to assess thyroid function?because small changes in circulating thyroid hormones result in larger changes in TSH (assuming no associated pituitary or hypothalamic disease)
Low TSH and high thyroid hormones indicates what?hyperthyroidism
Elevated TSH and low levels of thyroid hormones indicates what?hypothyroidism
Between 3% to 8% of the general population has subclinical hypothyroidism (SCH), define this?elevated TSH but normal free T4
The prevalence of SCH increases with age and is higher in what gender (although the gender difference is no longer present after 6th decade of life)?women
80% of individuals with SCH have mild elevation of TSH with levels between ___ to ___ mIU/L (normal 0.5 - 5.0 mIU/L)?5; 10
What thyroid antibodies are present in 80% of patients with SCH?thyroid peroxidase antibody
When making the dx, it is important to remember that TSH elevation can be transient, so what should be done?testing should be repeated
Also, TSH levels naturally increase with age (normal, 6-8 mIU/L) for individuals in their _____, so age-related normals must be considered when making the dx of SCH?80's
Patients with SCH, particularly those with TSH levels < ____ mIU/L, are usually asymptomatic, while others may present with mild or vague symtpoms consistent with overt hypothyroidism (fatigue, constipation)?10
In one study individuals > 55 years of age, mroe than 1/2 normalized their TSH levels over a mean follow-up of ____ months?32
*** Progression to overt hypothyroidism is more likely in patient with TSH > ____ miU/L and in those with ____ antibodies?10; TPO
*** The annual estimated rate of progression to overt hypothyroidism is ___% if TPO-AB neg and ___% if TPO-AB positive?2; 4
Individuals with TSH < ____ mIU/L have a lower likelihood of progression?6
Progression to overt hypothyroidism is associated with what adverse effects and should be carefully monitored?1) dyslipidemia 2) cardiovascular risk (atherosclerotic heart disease, heart failure) 3) cognitive, neuropsychiatric and neuromuscular dysfunction)
Is there association between hypothyroidsm or SCH with an increased risk of DM, thyroid cancer or hyperparathyroidism?no
True or false? While treatment of overt hypothyroidism reduces the risk of the adverse effects noted above, the evidence of the association of untreated SCH with these adverse effects is conflicting and the benefits of treatment in nonpregnant adults are not clear?true
*** The American Thyroid Association (ATA) and the American Association of Clinical Endocrinologists (ACCE) recommend treatment of patients with SCH and TSH > _____ mIU/L because of the increased potential for adverse effects and the increased risk of progression o overt hypothyroidism in this subgroup?10
Is there an consensus regarding the treatment of individuals with TSH levels ____ to _____ mIU/L?5; 10
Individualization of therapy should take what into consideration?1) presence of symptoms 2) degree of elevation of TSH (treating those with higher TSH levels) 3) presence of TPO antibodies, indicating a higher risk of progression 4) presence of atherosclerotic heart disease, heart failure or risk factors for these disease
Why do most experts caution against over treatment of older individuals?there is a normal increase in TSH with age
True or false? A recent study found that treating the elderly with subclinical hypothyroidism did not result in improvement in fatigue scores nor in cognitive function or performance of activities of daily living?true
If treatment is needed, what medication is used for the aim of TSH to be within the normal range?levothyroxine (LT4)
LT4 is considered standard of care and is strongly recommended; is there any evidence of superiority of combination T3/T4 therapy, T3 alone or desiccated thyroid extracts?no
SCH in reproductive-aged women whoa re attempting pregnancy or are pregnant require special mention. Are data regarding the effect of SCH on fertility conclusive?no, they are inconclusive
Is there sufficient data to conclude that SCH is associated with infertility?no
True or false?The 2017 ATA guideline states that thee are insufficient data to recommend for or against routine treatment with thyroxine for women who have SCH, infertility, are TPO-AB negative and are attempting conception but not undergoing advanced reproductive technology?true
*** Is it recommended that women with SCH that undergo invitro fertilization or intracytoplasmic sperm injection receive LT4 treatment?yes
The TSH levels considered the upper limits of normal are different in pregnancy, give the levels?1) 1st trimester = 2.5 mIU/L 2)2nd trimester = 3.0 mIU/L 3) third trimester = 3.5 mIU/L
Is it clear if the 2.5 mIU/L level be used as the upper limit for women attempting pregnancy for whom treatment is being considered?no
What are the goals for treatment of pregnant women with SCH?aim to maintain TSH levels within pregnancy - specific normal ranges
Treatment initiation in pregnant women does not require repeat testing, why?because of the potential adverse effects of SCH on pregnancy and fetus
What is the recommendation strength and evidence quality for "LT4 therapy is recommended for women TPO-Ab positive and TSH > pregnancy-specific reference range"?strong, moderate
What is the recommendation strength and evidence quality for "LT4 therapy is recommended for women TPO-AB negative and TSH > 10 mIU/L"?strong; low
What is the recommendation strength and evidence quality for "LT4 therapy may be considered for women TPO-AB positive with TSH > 2.5 mIU/L and below the upper limits of pregnancy-specific reference range"?weak; moderate
What is the recommendation strength and evidence quality for "LT4 therapy may be considered for women TPO-AB negative with TSH > pregnancy-specific reference range and below 10 mIU/L"?weak; low
What is the recommendation strength and evidence quality for "LT4 therapy is NOT recommended for women TPO-AB negative with TSH within the pregnancy-specific reference range"?strong, weak
Comment on presence of TPO-antibodies (autoimmunity)?1) associated with miscarriages (good evidence) 2) associated with infertility (fair evidence)
Comment on pregnancy loss/premature delivery?1) increasing risk with higher TSH levels; presence of TPO-antibodies further increases risk 2) treat if TSH > 4 mIU/L (good evidence) 3) treat if TSH is 2.5 - 4 mIU/L (insufficient evidence)
Comment on adverse neurodevelopment outcomes?1) no evidence that prepregnant TSH 2.5 - 4.0 mIU/L is associated with adverse effects 2) SCH diagnosed in pregnancy is associated with adverse neurodevelopment outcomes (fair evidence) 3) treatment of SCH improves neurocognitive outcomes (insufficient evidence) - ATA 4) treatment does not improve development outcomes (fair evidence) - ASRM
*** SUMMARY = Define SCH?elevated TSH but normal levels of free T4
*** SUMMARY = Between ____and ____% of the general population has subclinical hypothyroidism?3; 8
*** SUMMARY = It is generally recommended that individuals with SCH and TSH levels > _____mIU/L receive treatment with Levothyroxine?10
*** SUMMARY = True or false? SCH has potential adverse effects on fertility, pregnancy, fetal and neonatal development?true