Establishing accurate reference ranges for thyroid hormones is a subject of considerable debate within the medical community. Much of the controversy centers around the upper limit value for thyroid stimulating hormone (TSH), which is secreted by the pituitary gland and tells the thyroid to produce thyroxine. Elevated TSH means that the thyroid is not producing enough thyroxine, indicating a possible hypothyroid state. Hypothyroid signs and symptoms comprise a wide and diffuse spectrum, and many people go undiagnosed because their blood values fall within the currently established ranges.
Neuromuscular
People with undiagnosed hypothyroidism -- i.e., having symptoms that are not supported by blood hormone levels -- have a high occurrence rate of symptoms such as muscle pain, muscle weakness and fatigue, joint pain, and tingling in the hands and feet. Understandably, these symptoms can be easily explained by many other conditions, including stress, arthritis, neurologic conditions and age. Researchers at the Department of Internal Medicine, University of Pisa School of Medicine, concluded that early treatment is beneficial to these patients as opposed to following them to see if their blood values progress to clinical significance.
Metabolic
The thyroid gland orchestrates metabolic activity throughout the body; therefore, hypothyroid symptoms typically manifest as disturbances of energy levels, weight gain or difficulty losing weight, hypersensitivity to cold and muscle fatigue. Hypothyroid individuals might have lethargy during the day, yet an inability to fall asleep or stay asleep at night. Another cardinal metabolic sign is that physical activity creates the sense of sufficient energy, whereas when the activity ceases, fatigue returns and there is a tendency to nod off. Slower metabolism also leads to chronic constipation.
Mood and Memory
Researchers in the divisions of endocrinology, diabetes, and clinical nutrition and biostatistics, and the department of behavioral neurosciences at Oregon Health and Science University concluded in a study published in the "Journal of Clinical Endocrinology & Metabolism" that subclinical hypothyroidism impairs mood and also the areas of the brain involved with short-term memory. The connection to low thyroid function can go unnoticed when middle or advancing age is a concomitant factor.
Hair and Skin
Thinning, dryness and brittleness of the hair are often observed, along with thickening, dryness and coarseness of the skin. Around the eyes, typical signs include puffiness, drooping of the lids, loss of the outer third of the eyebrow and yellow bumps on the eyelids. Another common skin sign is yellowing of the palms of the hands and soles of the feet, which occurs from carotene accumulation in the lipids of the thickened skin.
References
- Mayo Clinic: A Practical Approach to the Treatment of Subclinical Hypothyroidism
- Annals of Clinical Biochemistry: The upper limit of the reference range for thyroid-stimulating hormone should not be confused with a cut-off to define subclinical hypothyroidism
- Clinical Endocrinology: Neuromuscular symptoms and dysfunction in subclinical hypothyroid patients: beneficial effect of L-T4 replacement therapy
- Natural News: Hypothyroidism Reaches Epidemic Proportions, Causing Fatigue and Weight Gain
- EndocrineWeb: Hypothyroidism: Too Little Thyroid Hormone
