Clinical Criteria
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History taking to evaluate patients at risk
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Symptoms/signs of thyroid hormone deficiency
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Evidence of disease/ previous treatment or exposure known to cause thyroid/pituitary/ hypothalamic failure
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Conditions associated with increased risk of chronic autoimmune thyroiditis
Laboratory Testing
Specific tests
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Include measurement of TSH, T4 or FT4 (FreeT4),T3 or, FT3 (FreeT3) |
In primary hypothyroidism
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Decreased T3, T4 levels with elevated TSH or |
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Normal T3 lowT4 and high TSH / |
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LowT3 occurs in severe cases |
In subclinical hypothyroidism
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Normal T 3, T4 levels with elevated TSH levels |
In central hypothyroidism
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Low T 3, and T 4 levels with normal or low TSH |
T 3, T 4, TSH Levels
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T3, T4 Normal TSH Normal
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T3, T4 Normal TSH High
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T3, T4 Low TSH High or |
T3, T4 Low TSH Normal or |
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T3 Normal T4 Low TSH High |
T3, T4 Low TSH Low
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Normal |
Subclinical Hypothyroidism |
Primary Hypothyroidism |
Central Hypothyroidism |
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In autoimmune thyroid disease causing hypo- thyroidism, antimicrosomal antibodies are present in 90% of patients. |
Neonatal screening for congenital hypothyroidism
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It was introduced in 1974.. |
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This has improved the prognosis of patients with congenital hypothyroidism. |
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Ideally, screening should be done with T 4 and TSH levels by 4th day of neonatal life and reconfinned by with following values. |
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FT4 < 6ug/dl and TSH > 20-40 uIU /L |
In case of central hypothyroidism
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MRI brain and pituitary
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Other honnonal evaluation
Typical reference ranges for Serum Thyriod Hormones and TSH*
* Reference ranges may vary according to laboratory
| Hormone | Serum Levels |
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TSH Free T4 T4 Free T3 T3 |
0.2-5.0 uIU/ml 0.8-2.0 ng/dL 4.5-12.5 ug/dL 1.4-4.4 pg/ml 86-186 ng/dL |
Early diagnosis can be a major step forward in the treatment of hypothyroidism.