Potential need for race-specific
diagnostic criteria and healthcare delivery
for thyroid hormone abnormalities
Yutaka Aoki
Morgan State University
School of Community Health and Policy
October 21, 2010
Seventh National Conference on Quality Health
Care for Culturally Diverse Populations
Racial disparities & SES:
Brief Overview
• Race represents many factors
• Minority race/ethnicity often associated w/
– Lower income
– Lower education
– Etc.
• These correlates often termed collectively
as socioeconomic status (SES)
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SES as basis for Racial Disparities
in Health
• SES is often mediator in many racial disparities
– E.g., in asthma, cardiovascular disease, etc.
– Minority race
 Low SES (common in minority)
 Limited access to high-quality healthcare
 More/severe disease
• Other mediators
–
–
–
–
Unhealthy life style?
Stress/discrimination?
Limited access to grocery (fresh fruits & vegetables)?
Others
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Known racial difference with
genetic basis
• Some racial difference has
biological/genetic bases, e.g.:
– Sickle Cell Disease more common in African
Americans (AAs)
• Genetics non-modifiable unlike:
• Unhealthy life style—may be modified through
behavioral intervention
• Discrimination—may be modified through societal
changes
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Biology/Generics or SES?
• Often answer is not “one or the other”
• Could be intertwined
– E.g., in breast cancer
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Intertwined Relationship:
Breast Cancer in Case
Lower incidence & higher mortality in AAs
• Thought as access-to-care issue
– Mammography in last 2 years: 63% in blacks
vs. 67% in whites (Chagpar et al, 2008, Surgery)
• Has turned out breast cancer of black
women tend to be more fatal type
– i.e., different breast cancer in minority (Dunn et
al., 2010, Breast Cancer Res Treat)
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Disease itself, not just risk for same
disease, may vary across races
• Different manifestations—signs and
symptoms
• Different description of same symptoms by
patients
• Distribution of disease biomarkers
among individuals with or without
disease
– Focus of this presentation
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Case in point:
Thyroid hormone abnormalities
• Different profile of thyroid health for nonHispanic whites, blacks, and Hispanics (Aoki et al.,
2007, Thyroid)
• Does difference arise from:
– Biological difference?
– Access to care/SES?
• This presentation deals with:
– Unanswered questions
– Implications
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Thyroid hormone basics:
Signs and symptoms
• Hypothyroidism—too little thyroid hormone
– Signs and symptoms decreased metabolism
– Weight gain, sluggishness/tiredness,
depression, slow heart beats, etc.
• Hyperthyroidism—too much thyroid hormone
– Symptoms and signs of increased
metabolism
– Weight loss, bone loss, restlessness, rapid
heart beats, high appetite, etc.
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Thyroid hormone basics:
Diagnosis
• Measure serum T4 (thyroxine)
– Low T4—hypothyroidism
– High T4—hyperthyroidism
• Serum TSH (thyroid stimulating hormone)
actually used more often for dx, though
– High TSH—hypothyroidism
– Low TSH—hyperthyroidism
• Note flip in high/low
– T4 and TSH negatively associated
– People with high T4 tend to have low TSH, vice versa
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African American (AA)-white
difference in thyroid health
• AAs have:
– Higher total T4, lower TSH than whites
– Lower hypothyroidism prevalence
– Higher hyperthyroidism prevalence
(Aoki et al., 2007, Thyroid)
• Biological basis—Caucasians adapted to
colder climate in Europe (vs. Africa)
• Is “access to care” a factor?
– Largely unanswered (but probably not so)
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Thyroid hormone abnormality’s
long-term consequences
• Hypothyroidism can cause/associated with:
– CVD (Ochs et al., 2008, Ann Intern Med)
• Treatment for hypothyroidism associated with:
– More hospitalizations, greater use of non-thyroid
prescription medications (Aoki, unpublished)
• Hyperthyroidism can cause/associated with:
– CVD (Ochs et al., 2008, Ann Intern Med)
– Osteoporosis (Biondi et al., 2005, Eur J Endocrinol)
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Higher CVD mortality/morbidity for
blacks
• Thyroid health difference may play some
(small) roles
• Probably small roles because
hypo/hyperthyroidism is not common:
– Hypothyroid blacks may be undertreated with
current universal tx goal, yet blacks have
relatively low hypothyroidism prevalence
– Hyperthyroidism, which is more common in
blacks, still is relatively rare (prevalence ≈ 1%)
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Universal (non race-specific)
cut-offs used for most studies
• Cut-offs has been in use for decades (with
revisions)
• Apparently earlier clinical studies
conducted in majority Caucasians
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“Universal” cut-offs for
hyperthyroidism appropriate?
Suppose a black patient has TSH = 0.08 mIU/L
(i.e., slightly below universal cut-off of 0.08 mIU/L
for hyperthyroidism)
Standard interpretation and action
• Slightly below cut-off equally bad for blacks
and whites
• Treat accordingly
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“Universal” cut-offs for hyperthyroidism
appropriate? (cont’d)
Suppose a black patient has TSH = 0.08 mIU/L
(i.e., slightly below universal cut-off of 0.08 mIU/L
for hyperthyroidism)
Alternative interpretation and action
• TSH = 0.08 mIU/L may be OK for blacks, if
blacks “naturally” tend to have lower TSH
(and higher T4, i.e., be on hyperthyroid side)
• Don’t treat
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“Universal” cut-offs for hypothyroidism
appropriate?
• When treating hypothyroid black patients:
– Should we try to lower TSH in range between
0.5 - 2.0 mIU/L (as currently recommended
irrespective of race in NACB, 2002)?
or
– Should we try to set a lower range for TSH for
blacks?
(recall blacks “naturally” have lower TSH and
higher T4)
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Potential healthcare implications
for genetic racial difference
1. Race-specific diagnostic criteria
2. Race-specific treatment regimen
3. Culturally-sensitive strategies for patient
education
• Research on #1 and #2 missing to date
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Clinical knowledge gaps
• Do we need race-specific diagnostic
criteria for thyroid hormone abnormalities?
• Do we need race-specific treatment goals
for thyroid hormone abnormalities?
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How to fill “clinical knowledge
gap”?
• Determine whether hypothyroidism
symptoms increases with decrease in T4
in a similar manner for blacks and whites
• Determine whether hyperthyroidism
symptoms increases with increase in T4 in
a similar manner for blacks and whites
• Determine whether hypo/hyperthyroidism
treatments work similarly for blacks and
whites (can use same Tx goals?)
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Challenges in research on
symptoms
• Symptoms could be (reported) differently
by racial groups!
– E.g., for major depression (Uebelacker et al.,
2009, Psychol Med)
• “Tolerable” levels may vary by race
– Physiological
– Cultural
• Translation issues in healthcare setting
(questionnaire/interview)
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Alternative to symptoms as
outcome to study
• Use other clinical (“hard”) outcome, e.g.,
CVD or osteoporosis, rather than
hypo/hyperthyroidism signs and symptoms,
e.g.:
– CVD
– Total mortality
– Osteoporosis
– QOL
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Alternative research strategies
• Determine whether risk of CVD and other
consequence of hypo/hyperthyroidism
increases with decrease in thyroxine in a
similar manner for blacks and whites
• Determine whether hypo/hyperthyroidism
Tx works similarly for blacks and whites in
CVD prevention
Both addresses race as effect modifier
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Implication for race-specific dx
criteria or tx goal
Doctor/Nurse: We will treat you (black
patient) differently from white patient.
• Potentially objectionable/confusing
message
• Message need to be delivered culturallysensitive, politically-correct manner
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Related debate: Need age-specific
cut-offs for thyroid hormones?
• There is age-related change in distribution
of thyroid hormone levels
– As people age:
• T4 lowers & TSH rises
• More spread for both
• Ongoing debate:
– Should we have separate cut-offs for elderly?
• Yes. (Surks &Hollowell, 2007, J Clin Endocrinol
Metab)
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Summary
• Race-specific diagnostic criteria and
treatment regimen may be needed for
thyroid hormone abnormalities
• If the need proven, careful delivery of
messages needs to be developed
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