Signs and Symptoms of Overt Hypothyroidism to Monitor
If your TSH rises above 10 mIU/L or your free T4 drops below normal, you should watch for classic hypothyroid symptoms and seek medical attention, as untreated overt hypothyroidism can lead to serious complications including heart failure and severe metabolic slowing. 1
Metabolic and Energy-Related Symptoms
Watch for profound fatigue that doesn't improve with rest, unexplained weight gain despite no change in diet, and persistent sensitivity to cold temperatures. 2 These symptoms reflect your body's slowed metabolism when thyroid hormone becomes insufficient. 2
- Severe, unrelenting fatigue that interferes with daily activities is one of the cardinal signs 3, 2
- Unexplained weight gain of 5-10 pounds or more, even without increased caloric intake 3, 2
- Cold intolerance where you feel cold when others are comfortable, particularly in your hands and feet 2, 4
- Constipation that becomes persistent and doesn't respond to usual remedies 2, 4
Physical Changes You Can See
Look for puffiness around your eyes and face, thinning hair that falls out more than usual, and dry skin that doesn't improve with moisturizers. 2 These changes occur because polysaccharides accumulate in tissues when thyroid hormone is deficient. 2
- Facial puffiness, especially around the eyelids and cheeks 2
- Hair loss that is diffuse (all over the scalp) rather than patchy 2, 5
- Dry, coarse skin that may feel rough or scaly 2
- Hoarseness or deepening of voice due to tissue swelling in the vocal cords 2
Cardiovascular Warning Signs
Pay attention to a slower heart rate (below 60 beats per minute when resting), new or worsening shortness of breath, or swelling in your ankles. 6 Untreated hypothyroidism causes cardiac dysfunction including delayed relaxation and abnormal cardiac output, which can manifest as heart failure. 1
- Bradycardia (slow heart rate) that you might notice as feeling your pulse is unusually slow 6
- Shortness of breath with minimal exertion or when lying flat 1
- Ankle swelling that worsens throughout the day 1
- Elevated blood pressure, particularly diastolic (the bottom number) 1
Cognitive and Mood Changes
Be alert for mental slowing, difficulty concentrating, memory problems, or new-onset depression. 3, 5 Middle-aged patients with worsening hypothyroidism commonly experience cognitive impairment and altered mood. 5
- Slowed thinking where you feel like your brain is "foggy" 3, 5
- Memory problems, particularly with short-term memory 5
- Depression or mood changes that develop without other explanation 5
- Difficulty concentrating on tasks that were previously easy 5
Reproductive and Menstrual Changes (for Women)
Watch for heavier or more frequent menstrual periods, or complete cessation of periods. 1 Thyroid hormone directly affects menstrual cycle regulation. 1
When to Seek Immediate Medical Attention
Contact your doctor urgently if you develop severe fatigue that prevents you from performing daily activities, significant unexplained weight gain (more than 10 pounds), or any cardiovascular symptoms like chest pain, severe shortness of breath, or marked ankle swelling. 3, 1 These may indicate progression to severe hypothyroidism requiring prompt treatment. 3
Critical Timing Considerations
Because 30-60% of mildly elevated TSH levels normalize spontaneously, your doctor should recheck your TSH and free T4 after 3-6 weeks before making treatment decisions. 1, 2 However, if you develop clear symptoms of hypothyroidism before that recheck, contact your doctor sooner rather than waiting. 2
Important Caveats
Some symptoms like fatigue and weight changes are non-specific and can have many causes besides thyroid disease. 5 Don't assume every symptom is thyroid-related, but do report new or worsening symptoms to your doctor so they can determine if your thyroid function needs reassessment. 5
The risk of progression from subclinical to overt hypothyroidism is approximately 2-5% per year overall, but increases significantly if you have positive anti-thyroid peroxidase (TPO) antibodies or if your TSH continues to rise. 7, 6 Your doctor may check TPO antibodies to assess your individual risk. 7