7. Muscle weakness
Muscles of our body need thyroid hormones to function properly, and deficiency of the thyroid hormones can cause severe muscle weakness and pain. Patients with underactive thyroid often complain of muscle strains and weakness, but this weakness is due to lack of thyroid energy, not due to breakdown of muscles.
Patients with hypothyroid also complain of paresthesia (tingling sensations, like pins and needles) and peripheral neuropathy (numbness, weakness, or pain, usually in the feet or hand). According to a study, 70% of the patients with underactive thyroid had abnormal electromyograms, which measure the electrical activity of different muscles of body (at rest and during contraction).
8. Hoarseness of Voice
Hoarseness of voice is also a common symptom of underactive thyroid. Hypothyroidism leads to swelling and thickness of mucous membranes of larynx and vocal cords and this swelling leads to hoarseness of the voice.