Hypothyroidism

Causes & Risk Factors

Hypothyroidism can result from several underlying causes:

•  Autoimmune thyroiditis (Hashimoto thyroiditis) — the most common cause in many populations, where the immune system gradually damages the thyroid gland.

•  Iodine deficiency — an important cause in regions with inadequate dietary iodine.

•  Previous thyroid surgery or radioactive iodine treatment.

•  Certain medications, including some used for other conditions, can affect thyroid function.

•  Congenital hypothyroidism, present from birth in some infants.

•  Pituitary or hypothalamic disorders, a less common cause affecting thyroid-stimulating hormone production.

Symptoms & When to Test

Hypothyroidism symptoms often develop gradually and can be nonspecific, sometimes attributed to aging or other causes before thyroid dysfunction is considered.

•  Fatigue

•  Weight gain

•  Cold intolerance

•  Constipation

•  Dry skin

•  Hair loss

•  Menstrual irregularities

•  Difficulty concentrating

When Should You Consider Testing?

Testing is generally appropriate for persistent symptoms suggestive of hypothyroidism, particularly when several of the above symptoms occur together, or as part of screening in individuals with risk factors such as a family history of thyroid disease or other autoimmune conditions.

Why Tests Are Combined

TSH is used as the initial test because it is typically the most sensitive indicator of thyroid dysfunction, rising even before free T4 falls outside the normal range in early or mild hypothyroidism — this is why TSH usually comes first, with Free T4 added to confirm and characterize the severity of dysfunction.

Anti-TPO and anti-thyroglobulin antibodies are added when autoimmune thyroid disease (Hashimoto thyroiditis) is suspected, since identifying an autoimmune cause can have implications for long-term monitoring and family risk, even though the immediate treatment approach for confirmed hypothyroidism may be similar regardless of cause.

This layered approach — starting with TSH, adding Free T4, then antibodies where relevant — reflects both diagnostic efficiency and cost-effectiveness, testing only what is needed to reach a clear answer for each patient's specific situation.

Tests Available at NPL

Preparation requirements vary by specific test — please follow the instructions provided by your doctor or NPL for the tests ordered.

Home Sample Collection

NPL offers convenient home sample collection for Hypothyroidism blood tests, so you don't need to visit a lab in person.

→ Book your test online, via the NPL app, or by calling +977 1 5970147 and select a convenient time slot for home sample collection.

→ A certified and experienced NPL phlebotomist visits your home at the scheduled time, following strict hygiene and safety protocols.

→ Your sample is transported under controlled, monitored conditions to NPL's ISO NABL ACCREDITED UNDER ISO15189:2022 laboratory for processing.

→ Your digital report is delivered securely to your phone or email, along with access to download and share it as needed.

When to See a Doctor

•  Persistent fatigue, weight gain, or cold intolerance

•  Unexplained constipation, dry skin, or hair loss

•  Menstrual irregularities alongside other suggestive symptoms

•  Family history of thyroid disease

•  Known hypothyroidism with symptoms suggesting inadequate treatment