Hypothyroidism
Hypothyroidism means the body does not have enough thyroid hormone. Fatigue, constipation, cold intolerance and weight changes can occur, but these symptoms overlap with other conditions. A diagnosis depends on appropriate clinical assessment and laboratory findings rather than a symptom checklist alone.
How is an underactive thyroid evaluated?
TSH is commonly the initial test, interpreted with free T4 when indicated. A raised TSH with low free T4 differs from a raised TSH with free T4 still in range. Pregnancy, pituitary disease, recent illness and medication use can change interpretation. Bring the actual reports, units and reference ranges rather than a recollection that a result was normal.
Does everyone need the same medication?
Levothyroxine is the usual hormone replacement for established hypothyroidism. The prescribing clinician determines whether treatment is indicated, the dose and follow-up. Persistent symptoms warrant a careful review, not unsupervised dose escalation. This practice resource is not an offer of prescribing or a substitute for medication monitoring.
What if symptoms persist?
A review can consider medication administration, supplements, sleep quality, anemia, mood, menopausal symptoms and other explanations. More tests are not automatically better. A useful test answers a specific question and has a realistic next step if the result is abnormal.
What different tests can and cannot answer
| Clinical question | Possible starting point | Important limitation |
|---|---|---|
| Is thyroid function abnormal? | TSH, with free T4 as appropriate | Interpretation depends on context, medicines and pregnancy. |
| Is autoimmunity involved? | Selected thyroid antibody tests | Positive antibodies do not establish the degree of hormone deficiency. |
| Is there a structural lump? | Examination and ultrasound, with specialist assessment | Normal hormone tests do not exclude an important nodule. |
| Does a food cause allergy? | Reaction history and appropriately selected allergist testing | A food IgG panel cannot diagnose or exclude allergy. |
| Are stress symptoms an adrenal disease? | Medical history and validated testing when indicated | “Adrenal fatigue” is not an established diagnosis. |
Questions and answers
How is an underactive thyroid evaluated?
TSH is commonly the initial test, interpreted with free T4 when indicated. A raised TSH with low free T4 differs from a raised TSH with free T4 still in range. Pregnancy, pituitary disease, recent illness and medication use can change interpretation. Bring the actual reports, units and reference ranges rather than a recollection that a result was normal.
What if symptoms persist?
A review can consider medication administration, supplements, sleep quality, anemia, mood, menopausal symptoms and other explanations. More tests are not automatically better. A useful test answers a specific question and has a realistic next step if the result is abnormal.
Sources and further reading
- American Thyroid Association: Thyroid hormone treatment
- American Thyroid Association: Hashimoto’s thyroiditis
- NIDDK: Thyroid tests
- American Thyroid Association: Thyroid function tests
- NIDDK: Hashimoto’s disease
- NIDDK: Graves’ disease
- American Thyroid Association: Thyroid nodules
- Endocrine Society: Adrenal fatigue
- AAAAI: Limits of food IgG panel testing
- NIDDK: Diagnosis of celiac disease
- American Thyroid Association: Hypothyroidism during pregnancy
Educational information only, not medical advice, diagnosis or a treatment plan. Do not stop, start or change prescribed medication based on this resource. Pregnancy, children, significant heart symptoms and complex endocrine disease require appropriate medical care. Seek emergency help for chest pain, severe breathing difficulty, fainting, or high fever with confusion and a very fast heartbeat. A discovery call is not urgent medical care.