Fatigue, hair fall and weight change often lead people to request a “thyroid test.” These symptoms deserve attention, but they can have several causes. Thyroid care works best when the symptom pattern, blood results, medicines and life stage are considered together.
Underactive or overactive: what is the difference?
An underactive thyroid, or hypothyroidism, does not produce enough thyroid hormone. Symptoms may include feeling cold, constipation, tiredness, dry skin, hair thinning, weight gain or menstrual changes.
An overactive thyroid, or hyperthyroidism, produces too much hormone. It may cause a racing heart, shaky hands, heat intolerance, sweating, weight loss or frequent stools. Not everyone has every symptom, and symptoms alone cannot establish either diagnosis.
What do TSH, FT4 and Anti-TPO mean?
TSH is a signal from the brain's pituitary gland telling the thyroid to work. In common primary hypothyroidism, TSH rises because the gland is not making enough hormone. A high TSH therefore does not usually mean that the thyroid is overactive.
For most adults without suspected pituitary disease, TSH is the first test. The clinician may add free T4 if TSH is high, or free T4 and free T3 if it is low. Pregnancy, acute illness and pituitary disease require different interpretation.
Anti-TPO antibodies can help identify an autoimmune cause in selected patients; repeatedly measuring them does not usually guide the dose. Ultrasound is useful for particular findings, such as a neck lump, rather than automatically for every abnormal blood result.
Tell the doctor and laboratory about biotin-containing hair or nail supplements. They can distort some thyroid results. Follow the laboratory's advice about interruption; there is no single interval suitable for every dose and test.
How should levothyroxine be taken?
Levothyroxine replaces missing hormone. Take it consistently as prescribed, usually on an empty stomach 30–60 minutes before breakfast, tea or coffee. Calcium and iron supplements generally need at least a four-hour gap. Discuss your full medicine list and any difficulty following the schedule.
Do not copy another person's dose. After a dose change, allow the clinician's recommended interval before retesting; hormone levels do not settle immediately. Too much replacement can cause harm as well as too little.
A normal report may mean the medicine is working. Some causes need long-term treatment, while others may be temporary. Stop or reduce treatment only after an individual review.
Is overactive thyroid treated with the same medicine?
No. Depending on the cause, treatment may involve antithyroid medicines, radioiodine, surgery or a different approach for thyroiditis. “Thyroid boosters,” kelp or extra iodine are not universal cures and can worsen some conditions.
If you take an antithyroid medicine and develop fever or a sore throat, seek urgent prescribing-team advice because a rare blood-cell side effect needs assessment. Severe palpitations with fever, confusion, chest pain or collapse needs emergency care.
Planning a pregnancy?
Contact the doctor before pregnancy or promptly after a positive pregnancy test. Thyroid targets and doses may change. Pregnancy interpretation should use appropriate laboratory and trimester-specific ranges; a single internet TSH cut-off does not fit everyone. Continue prescribed care and follow any personalised adjustment plan already agreed with your doctor.
Common questions
Does high TSH mean “thyroid is high”?
The wording is confusing. High TSH often indicates low thyroid function; the full result matters.
Can I stop medicine when the report is normal?
Do not stop it yourself. Discuss the cause, dose and monitoring plan first.
Where can I get thyroid care in Patna?
The thyroid, BP and metabolic clinic can review symptoms, reports and medication. Bring previous results with dates, the medicine strip and all supplements. Read more about related blood-pressure care.
Sources
NICE NG145; NIDDK information on hypothyroidism and hyperthyroidism; NHS levothyroxine advice; ATA hormone-treatment information and the 2026 pregnancy guideline.
This article is for health education and does not replace an individual medical consultation. Symptoms, test results, medicines, and treatment decisions should be discussed with a qualified clinician.
Seek urgent medical care for severe breathing difficulty, chest pain, confusion, fainting, uncontrolled bleeding, severe dehydration, or rapidly worsening symptoms.