Hyperthyroidism symptoms and weight loss: what to know

Weight loss has many possible causes, so this symptom alone cannot confirm an overactive thyroid. Arrange a medical assessment if the change is unplanned, continues, or comes with other new symptoms.

The thyroid makes hormones that influence how quickly the body uses energy. In hyperthyroidism, hormone levels are too high for the body's needs. This can increase calorie use and lead to weight loss even when appetite is unchanged or stronger. Some people also notice frequent bowel movements or diarrhoea, muscle weakness, trembling, tiredness, or changes in menstrual periods.

Symptoms can develop gradually or become noticeable over a short time. The pattern may be linked to an autoimmune thyroid condition, thyroid inflammation, or a thyroid nodule that produces hormone. A clinician usually considers your symptoms, medicines, examination findings, and medical history before deciding which tests are appropriate.

Book an appointment with a general practitioner if you are losing weight without trying, particularly if you also have a racing or irregular heartbeat, increased sweating, feeling anxious, trouble sleeping, or discomfort in warm surroundings. Keep a brief record of the change, your appetite, bowel symptoms, sleep, heartbeat sensations, medicines, and any supplements.

Blood tests can check thyroid-stimulating hormone and thyroid hormones. Depending on the results and examination, further testing or referral may be considered. Do not start iodine products or thyroid medicines without medical advice, because they can alter thyroid function or interfere with treatment.

Seek urgent medical help for chest pain, severe shortness of breath, fainting, new confusion, or a very fast or markedly irregular heartbeat. A high temperature with severe agitation, vomiting, profound weakness, or collapse also needs emergency assessment. These symptoms can signal a serious problem and should not be explained away as ordinary weight loss.

You could ask: Could my symptoms be related to thyroid hormone levels? Which blood tests do I need? Could any medicine or supplement be affecting my thyroid? What changes should prompt urgent help? If hyperthyroidism is confirmed, when should my symptoms and weight be reviewed?