The thyroid gland, responsible for producing T3 and T4 hormones, can lead to various symptoms affecting a person's physical and mental health if it functions either too little or too much.

Symptoms observed in cases of an overactive thyroid gland (hyperthyroidism):
* Nervousness, anxiety, and restlessness
* Sleep problems
* Unexplained weight loss
* Excessive sweating and heat sensitivity
* Heart palpitations or rapid heartbeat
* Eye irritation or changes
* Tremors

Symptoms observed in cases of an underactive thyroid gland (hypothyroidism):
* Extreme fatigue and weakness
* Weight gain or difficulty losing weight
* Excessive sensitivity to cold
* Dry skin and brittle hair or hair loss
* Hoarseness or changes in voice
* Muscle weakness and joint pain
* Irregular periods or heavy bleeding
* Constipation
* Depressed mood
* Slow heartbeat

Symptoms such as swelling or the formation of nodules in the neck may also be observed in thyroid dysfunction. If you experience one or more of these symptoms, it is important to consult a healthcare professional for proper diagnosis and treatment.