Thyroid
Subclinical Hypothyroidism
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Subclinical Hypothyroidism
, Sick Euthyroid Syndrome, Euthyroid Sick Syndrome
See Also
Hypothyroidism
Definition
Elevated TSH with normal
Free T4
Epidemiology
Incidence
Older Men: 2-8%
Incidence
Older Women: 5-10%
Precautions
Normal TSH range increases with age up to 7.5 mIU/L for an 80 year old patient (see TSH)
Indications
Treatment
Thyroid Stimulating Hormone
(TSH) > 10 mU/ml or
Thyroid
peroxidase
Antibody
positive or
Symptoms with persistent mildly elevatad TSH
Depression
Fatigue
, Consgtipation, Cold intolerance,
Hair Loss
Hyperlipidemia
Goiter
Hyperhomocysteinemia
Coronary Artery Disease
or
Cardiac Risk Factor
s
Pregnancy or expected pregnancy
Complications
Coronary Artery Disease
(increased risk in elderly)
Treating patients with Subclinical Hypothyroidism may lower cardiovascular disease risk
Biondi (2002) Ann Intern Med [PubMed]
Management
See
Hypothyroidism
Levothyroxine
See
Levothyroxine
for standard dosing protocol if TSH >10 mIU/L
Dosing (indicated for TSH <10 mIU/L and indications listed above)
Younger than age 50 years
Start at 50 mcg daily and increase by 25 mcg every 6 weeks until goals met
Over age 50 years
Start at 12.5 to 25 mcg daily and increase by 12.5 to 25 mcg every 6 weeks until goals met
Goals for treating Subclinical Hypothyroidism
LDL Cholesterol
falls
Hypothyroidism
symptoms improve
TSH normalizes <4.0
Precautions: Avoid overtreatment with excessive
Levothyroxine
Risk of
Osteoporosis
worsening,
Atrial Fibrillation
Stop
Levothyroxine
if persistently subclinical (TSH <10) and no symptom improvement at 3-6 months
Monitoring
Aim to lower
Serum TSH
to mid-normal: 1 to 3 mU/ml
Course
Risk of longterm progression to overt
Hypothyroidism
TSH 4-6 mU/ml: No increased risk of future
Hypothyroidism
TSH >6 mU/ml: 27-42% risk of future
Hypothyroidism
TSH >6 mU/ml and
Thyroid
Peroxidase
Antibody
positive: >55% risk of future
Hypothyroidism
References
(2017) Presc Lett 25(1):4
(2012) Presc Lett 19(6): 34
Svec (2001) CMEA Medicine Lecture, San Diego
Hueston (2001) Am Fam Physician 64(10):1717-24 [PubMed]
Adlin (1998) Am Fam Physician 57(4):776-80 [PubMed]
Vanderpump (1995) Clin Endocrinol 43:55 [PubMed]
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