When you feel fatigue and it seems as if you are less energetic then it is high time to get your Thyroid checked. It might be Hypothyroidism, a very common phrase we hear these days affecting people in an enormous way. This is a condition where certain functions of the body is measured down leading to fatigue and various other problems.

1. HYPOTHYROIDISM

2. INTRODUCTION
 Hypothyroidism is defined as a deficiency in thyroid hormone
secretion and action that produces a variety of clinical signs and
symptoms of Hypometabolism.
1. Overt Hypothyroidism is defined as an elevated serum TSH
concentration (usually above 10 mIU/L) and reduced free
Thyroxine concentration (fT4)
2. Subclinical Hypothyroidism is defined as serum TSH above the
upper reference limit in combination with a normal free Thyroxine
(fT4)

3. Prevalence
 According to a projection from various studies on Thyroid disease,
it has been estimated that about 42 million people in India suffer
from Thyroid diseases. The prevalence of Hypothyroidism was
3.9%. The prevalence of subclinical Hypothyroidism was 9.4%. In
women, the prevalence was higher, at 11.4%, when compared
with men, in whom the prevalence was 6.2%. The prevalence of
subclinical Hypothyroidism increased with age. About 53% of
subjects with subclinical hypothyroidism were positive for anti-
TPO antibodies.

4. CLINICAL PRESENTATION
 Hypothyroidism can affect all organ systems &
these manifestations are largely independent of the
underlying disorder but are a function of the degree of
hormone deficiency.

6. CAUSES OF HYPOTHYROIDISM

7. HASHIMOTO’S THYROIDITIS
 Hashimoto’s Thyroiditis is an autoimmune disease in which the thyroid gland is
attacked by a variety of cell and antibody-mediated immune processes, causing
primary Hypothyroidism. The resulting inflammation from Hashimoto’s disease,
also known as Chronic Lymphocytic Thyroiditis, often leads to an underactive
Thyroid gland (Hypothyroidism).
 The diagnosis of Hashimoto’s Thyroiditis is supported by recognition of
autoantibodies against TPO or Thyroglobulin. 90% of patients with Hashimoto’s
Thyroiditis have anti-TPO antibodies and anti-Thyroglobulin antibodies, making
these antibodies excellent markers for Hashimoto’s Thyroiditis. Anti-TPO antibody
positivity is more common at the time of diagnosis than anti-Thyroglobulin
antibody.

8. Hypothyroidism in Pregnancy
 Convincing data suggest that pregnant women who are positive for Thyroid
autoantibodies (especially anti-TPO antibodies) leads to higher frequency of miscarriage
(13.8%) than is seen in pregnant women who lack anti-TPO antibodies (2.4%), and that T4
treatment of the anti-TPO antibody positive group reduces the risk of miscarriage to
approximately 3.5%.
 Over Hypothyroidism (OH) in pregnancy is defined as an elevated TSH (>2.5 mIU/L)
in conjunction with a decreased FT4 concentration. Women with TSH levels of 10.0 mIU/L
or above, irrespective of their FT4 levels, are also considered to have OH.
 Sub-clinical Hypothyroidism (SCH) in pregnancy is defined as a serum TSH between 2.5
and 10 mIU/L with a normal FT4 concentration.
 Isolated Hypothyroxinemia (IH) is defined as a normal maternal TSH concentration
in conjunction with FT4 concentrations in the lower 5th or 10th percentile of the
reference range.

9. Prevalence
 10%-20% of all pregnant women in the first trimester of pregnancy are Thyroid
Peroxidase (TPO) or Thyroglobulin (Tg) antibody positive and Euthyroid
 16% of the women who are Euthyroid and positive for TPO or Tg antibody in the
first trimester will develop a TSH that exceeds 4.0 mIU/L by the third trimester,
and 33%-50% of women who are positive for TPO or Tg antibody in the first
trimester will develop postpartum Thyroiditis
 2%–3% of apparently healthy, non-pregnant women of childbearing age have an
elevated serum TSH. Among these healthy non-pregnant women of childbearing
age it is estimated that 0.3%-0.5% of them would, after having Thyroid function
tests, be classified as having OH, while 2%–2.5% of them would be classified as
having SCH

10. Specific adverse outcomes associated
with maternal Hypothyroidism include:
 An increased risk of premature birth, low birth weight, and miscarriage. Such
patients carry an estimated 60% risk of fetal loss when OH was not adequately
detected and treated
 Negro and colleagues published data suggesting SCH also increases the risk
of pregnancy complications in anti-thyroid peroxidase antibody positive
(TPOAb+) women
 Negro et al. reported a significantly higher miscarriage rate in TPOAb+_ women
with TSH levels between 2.5 and 5.0 mIU/ L compared with those with TSH levels
below 2.5 mIU/L

11. Recommendations:
 Women who are positive for TPOAb and have SCH should be treated with LT4
 Women with SCH in pregnancy, who are not initially treated, should be
monitored for progression to OH with a serum TSH and FT4 approximately every 4
weeks until 16-20 weeks gestation and at least once between 26 and 32 weeks
gestation
 Isolated Hypothyroxinemia should not be treated in pregnancy

13. Recommendations:
 Anti-Thyroid Peroxidase Antibody (TPOAb) measurements should be considered
when evaluating patients with subclinical Hypothyroidism.
 If anti-thyroid antibodies are positive, Hypothyroidism occurs at a rate of 4.3%
per year versus 2.6% per year when anti-thyroid antibodies are negative.
 Assessment of serum free T4, in addition to TSH, should be considered when
monitoring L-thyroxine therapy.
 Treatment based on individual factors for patients with TSH levels between the
upper limit of a given laboratory’s reference range and 10 mIU/L should be
considered particularly if patients have symptoms suggestive of Hypothyroidism,
positive TPOAb or evidence of atherosclerotic cardiovascular disease, heart
failure, or associated risk factors for these diseases.

14. Recommendations:
 Patients whose serum TSH levels exceed 10 mIU/L are at increased risk for heart
failure and cardiovascular mortality, and should be considered for treatment with
L-thyroxine.
 Euthyroid women (not receiving LT4) who are TPOAb + require monitoring
for Hypothyroidism during pregnancy. In addition to the risk of Hypothyroidism, it
has been described that being TAb + constitutes a risk factor for miscarriage,
premature delivery, Perinatal death , post-partum dysfunction, and low motor and
intellectual development (IQ) in the offspring.

15. TEST RANGE AVAILABLE

16. References:
1. Indian Journal of Endocrinology & Metabolism. 2011 Jul; 15(Suppl2): S78–S81.
2. Williams text book of Endocrinology, Eleventh edition
3. Tietz Textbook of Clinical Biochemistry, Fifth Edition
4. Clinical Practice Guidelines for Hypothyroidism in Adults: Cosponsored by the
American Association of Clinical Endocrinologists and the American Thyroid
Association

17. References:
1. Negro R, Schwartz A, Gismondi R, Tinelli A, Mangieri T, Stagnaro-Green A
2010 Universal screening versus case finding for detection and treatment of
thyroid hormonal dysfunction during pregnancy. J Clin Endocrinol Metab
95:1699–1707.
2. Negro R, Schwartz A, Gismondi R, Tinelli A, Mangieri T, Stagnaro-Green A
2010 Increased pregnancy loss rate in thyroid antibody negative women with
TSH levels between 2.5 and 5.0 in the first trimester of pregnancy. J Clin
Endocrinol Metab 95:E44–8

18. For more information about Health Disease visit https://www.lalpathlabs.com
Hyperthyroidism