Fatigue

• Fatigue or sluggishness can be a sign of hypothyroidism. If you suddenly begin experiencing unexplained fatigue, report it to your doctor.
  
  

Weight Gain

• Sudden weight gain that cannot be attributed to a change in diet or exercise can be a sign of hypothyroidism. As is also the case with fatigue, weight gain is a symptom of many medical problems. Report unexplained weight gain to your doctor.
  
  

Aches and Pains

• Experiencing muscle aches, tenderness or swelling in the muscles is a sign of hypothyroidism, as is muscle weakness. Some people may notice some pain, swelling or stiffness in the joints.
  
  

Cholesterol Level

• People with hypothyroidism commonly experience an elevated blood cholesterol level. Especially in people who have had their cholesterol monitored regularly, a blood test that suddenly comes back with an elevated reading could be a sign of hypothyroidism.
  
  

Hair and Fingernails

• Other common signs of hypothyroidism are thin or brittle hair, fingernails and toenails.
  
  

Other Early Symptoms

• Among the other early symptoms of hypothyroidism are depression, increased sensitivity to cold, dry or pale skin, hoarse voice, puffiness in the skin, heavier than normal menstrual periods and constipation.
  
  

Late Symptoms

• If hypothyroidism is left untreated, some symptoms may worsen and become more bothersome. Other symptoms can develop as well, including swelling in the arms and legs and skin that feels cool to the touch. In later stages, a chest X-ray may reveal that the heart has become enlarged.