What are early warning signs of thyroid problems in women

Did you know…

More than 12% of the U.S. population will develop a thyroid condition at some point in their lives.

• An estimated 20 million Americans have some form of thyroid disease.

• Up to 60% of those with thyroid disease do not know they have it.

• Women are five to eight times more likely than men to have thyroid problems.

• One woman in eight will develop a thyroid disorder during her lifetime.

• The causes of thyroid problems are largely unknown.

• Undiagnosed thyroid disease may put patients at risk of serious conditions including cardiovascular disease, osteoporosis and infertility.

• Pregnant women with undiagnosed or inadequately treated hypothyroidism face increased risk of miscarriage, preterm delivery and severe developmental problems in their children.

• Most thyroid diseases are lifelong conditions, manageable with medical attention.

Introduction

The thyroid is a small, butterfly-shaped gland sitting in the middle of the lower neck, straddling the trachea. Part of the endocrine system, it governs many of the body's important functions by producing and secreting hormones. Its main job is to control the speed of your metabolism — the process by which the body converts food into energy. Every cell in the body needs energy to function.

When the thyroid stops working properly, the effects reach the entire body.

Thyroid problems cover a range of disorders, which can leave the gland producing either too little thyroid hormone (hypothyroidism) or too much (hyperthyroidism).

These disorders can affect heart rate, mood, energy level, metabolism, bone health, pregnancy and a great deal else.

Understanding the thyroid gland

The thyroid is an endocrine gland, releasing hormones directly into the bloodstream. Hormones are chemicals that coordinate the body's functions by carrying messages through the blood to organs, skin, muscle and other tissue — telling the body what to do and when.

It is made up of thyroid follicle cells (thyrocytes), which create and store thyroid hormone (mainly T3 and T4), and C-cells, which secrete calcitonin.

• Thyroxine (T4) — the inactive form. This is the main hormone the thyroid makes and releases. Despite being produced in the greatest quantity, it has relatively little effect on metabolism itself. Once released into the bloodstream, T4 can be converted into T3 through deiodination, which happens chiefly in the liver, kidneys, pituitary, central nervous system and skeletal muscle.

• Triiodothyronine (T3) — the active form. The thyroid produces less T3 than T4, but its effect on metabolism is far greater. Most T3 comes from the conversion of T4.

• Reverse triiodothyronine (RT3) — produced in very small amounts; it reverses the effects of T3.

• Calcitonin — helps regulate blood calcium, assisting bone cells in processing calcium and adding it to bone.

The body controls thyroid hormone levels through a multi-step system:

1. The hypothalamus secretes thyroid-releasing hormone (TRH), which stimulates the pituitary gland.

2. The pituitary gland secretes thyroid-stimulating hormone (TSH), which stimulates the thyroid.

3. The thyroid releases thyroxine (T4, ~60%, inactive) and triiodothyronine (T3, ~20%, active) into the bloodstream.

4. Various organs — the liver, the kidneys and others — convert T4 into the active T3.

Producing thyroid hormones requires iodine, an element obtained from food: most commonly iodised table salt, algae and seaweed, and shellfish. The thyroid traps iodine and transforms it into thyroid hormone. Too little iodine, or too much, alters the level of hormone the gland can make and release.

Role of the thyroid in the body

The thyroid and its hormones touch nearly every organ system:

• Cardiovascular system — the thyroid helps regulate how much blood the heart pumps through the circulatory system (cardiac output), the heart rate, and the strength and vigour of the heart's contractions.

• Nervous system — when the thyroid malfunctions, symptoms can include numbness, tingling, pain or a burning sensation in affected parts of the body. Hypothyroidism can also cause depression, and hyperthyroidism can cause anxiety.

• Digestive system — the thyroid is involved in how food moves through the digestive tract (gastrointestinal motility).

• Reproductive system — thyroid dysfunction can produce irregular menstrual periods and fertility problems.

In summary, thyroid hormones affect:

• Metabolism

• Heart rate

• Breathing

• Digestion

• Body temperature

• Brain development

• Mental activity

• Skin and bone maintenance

• Fertility

Common thyroid disorders

There are several types of thyroid disease, some of them autoimmune — the immune system attacking the thyroid gland. The four main conditions are:

• Hypothyroidism (underactive thyroid) — the gland does not produce enough thyroid hormone. Hashimoto's disease, an autoimmune condition, is its most common cause.

• Hyperthyroidism (overactive thyroid) — the gland produces too much thyroid hormone. Graves' disease is a form of hyperthyroidism; it is autoimmune and genetic.

• Goiter (enlarged thyroid) — develops when the thyroid cannot make enough hormone to meet the body's needs and grows larger trying to compensate. It can also occur in people who don't get enough dietary iodine, which is required to make thyroid hormone.

• Thyroid cancer — classified according to the type of cells the cancer grows from.

Overview of hypothyroidism and hyperthyroidism

What is hypothyroidism (underactive thyroid)?

Hypothyroidism is among the most common thyroid problems. It occurs when the thyroid fails to produce and release enough thyroid hormone, which slows aspects of metabolism down. It is fairly common, affecting roughly 10 million people in the United States.

In its early stages hypothyroidism may produce no noticeable symptoms. Over time, untreated, it can lead to further problems including high cholesterol and heart disease.

Its most common cause is Hashimoto's thyroiditis, an autoimmune disorder that eventually stops the gland working.

It can be treated with thyroid hormone replacement therapy — levothyroxine, for instance — which replaces thyroxine (T4) levels.

Hypothyroidism causes

• Hashimoto's disease, an autoimmune disease

• Thyroiditis (inflammation of the thyroid)

• Iodine deficiency

• A nonfunctioning thyroid gland (where the thyroid does not work correctly from birth)

• Over-treatment of hyperthyroidism through medication

• Thyroid gland removal

Hypothyroidism symptoms

Symptoms vary with the severity of the condition:

• Fatigue and tiredness

• Increased sensitivity to cold

• Weight gain

• Puffy face

• Constipation

• Dry skin

• Coarse hair and skin

• Thinning hair

• Hoarse voice

• Muscle weakness, aches, tenderness and stiffness

• Heavier or irregular menstrual cycles

• Slow heart rate (bradycardia)

• Depression

• Memory problems

What is hyperthyroidism (overactive thyroid)?

Some thyroid disorders make the gland overactive, producing more thyroid hormone than the body needs — hyperthyroidism, which speeds aspects of metabolism up. Roughly 1 in 100 people over the age of 12 in the United States have it.

It is usually caused by the autoimmune condition Graves' disease. It can also result from a metabolically active thyroid nodule producing too much hormone, or from short-lived inflammation of the gland. Graves' disease can be treated with medication, radioactive iodine therapy or surgery.

Hyperthyroidism causes

• Graves' disease, an autoimmune condition

• Thyroid nodules

• Thyroiditis (inflammation of the thyroid)

• Postpartum thyroiditis (inflammation following childbirth)

• Excess iodine in the blood, from diet or medication

• Over-treatment of hypothyroidism through medication

• A benign (noncancerous) tumour in the pituitary gland

Hyperthyroidism symptoms

• Losing weight without trying

• Rapid heart rate (tachycardia)

• Irregular heartbeat (arrhythmia) and palpitations

• Increased hunger

• Sweating and increased sensitivity to heat

• Changes in menstrual cycles

• Changes in bowel patterns, particularly more frequent bowel movements

• Diarrhoea

• Nervousness, anxiety and irritability

• Sleep problems, tiredness

• Tremor, usually a slight trembling in hands and fingers

• Muscle weakness

• Thinning skin and brittle hair

• Enlarged thyroid gland (goiter)

General warning signs

• Slow or rapid heart rate

• Unexplained weight loss or weight gain

• Difficulty tolerating cold or heat

• Cold extremities

• Depression or anxiety

• Irregular menstrual periods

• Thinning hair

• Goiter — swelling at the front of the neck, just below the Adam's apple

• A feeling of tightness in the throat

• A change in the voice, such as hoarseness

How the liver and thyroid are connected

The liver modulates the endocrine system both directly and indirectly, in several ways — which makes it predictable that liver dysfunction is associated with a range of endocrine disorders. Among other things, the liver produces the carrier proteins for various hormones, and so indirectly modulates critical endocrine functions. The carriers for thyroid hormone are thyroid-binding globulin, transthyretin and albumin.

The liver is a first player in thyroid hormone transport and metabolism, including conversion and activation.

Thyroid status is essential to normal organ growth, development and activity, through the precise regulation of cellular activity in every human cell — hepatocytes included.

Since thyroid hormones govern cell metabolism throughout the body, it should be no surprise that the liver is affected by hypothyroidism. A complex interplay exists between the thyroid and the liver in health and in disease.

How the thyroid impacts your liver

Thyroid dysfunction — hypo- and hyperthyroidism both — can cause liver function abnormalities, affecting hepatocyte activity and hepatic metabolism. Impaired lipid metabolism, for example, leads to fatty liver and abnormal serum liver enzymes.

Thyroid hormones also contribute to bilirubin production and composition, partly through their involvement in lipid metabolism. In addition, the sphincter of Oddi in the small intestine expresses thyroid hormone receptors, and thyroxine (T4) has a direct relaxing effect on it — which helps move bile from the gallbladder and juices from the pancreas into the small intestine.

How hypothyroidism impacts your liver

Hypothyroidism on its own may be associated with slightly increased serum alanine aminotransferase (ALT) and gamma glutamyl transferase (GGT), likely reflecting the diminished lipid metabolism and hepatic steatosis reported in the condition.

In the general population, even subclinical hypothyroidism is associated with increased risk of developing NAFLD and fibrosis. Several mechanisms may contribute:

1. Hypothyroidism is associated with dyslipidemia and higher body mass index, both of which raise NAFLD risk.

2. Hypothyroidism-related insulin resistance may induce lipogenesis, promoting storage of free fatty acids in the liver.

3. Hypothyroidism increases adipocytokines such as TNFα and leptin while decreasing adiponectin, contributing to hepatic inflammation and fibrosis — either directly or indirectly, through increased oxygen free radicals (oxidative stress).

Gallstone disease is another common hepatic condition in which thyroid hypofunction may be an etiopathogenic factor. Cholesterol gallstones form when cholesterol crystals precipitate out of supersaturated bile, and hypothyroidism may favour that through three mechanisms:

1. A decrease in the rate of bilirubin excretion, caused by reduced activity of the bilirubin enzyme UDP-glucuronyltransferase, which impairs hepatic bilirubin metabolism.

2. Hypercholesterolemia, with higher concentrations of both total and LDL cholesterol.

3. Gallbladder hypomotility or impaired contractility, delaying emptying of the biliary tract.

How hyperthyroidism impacts your liver

The liver is a known target of thyroid hormone excess, given the relationship between that excess and liver damage.

Elevated serum alkaline phosphatase (ALP) is the most frequent abnormality in hyperthyroidism. Other common biochemical abnormalities include increased AST in 27% of patients, ALT in 37%, GGT in up to 62%, and raised total bilirubin.

How the liver can impact your thyroid

Liver dysfunction — whether from excess toxins, environmental pollutants or accumulated fat — can therefore account for substantial variation in the bioavailability of thyroid hormones.

Conclusion

Liver and thyroid are closely linked in the regulation of metabolism. The liver converts thyroxine (T4) into the active triiodothyronine (T3), and that active hormone then controls metabolism throughout the body. A healthy liver is essential to proper thyroid function, while thyroid hormones in turn shape liver metabolism and cholesterol levels. Dysfunction in either organ affects the other, with metabolic and broader health consequences.

References

Cited by the original article:

• American Thyroid Association: https://www.thyroid.org/media-main/press-room/

• Cleveland Clinic: https://my.clevelandclinic.org/health/diseases/8541-thyroid-disease

• Mayo Clinic — Hypothyroidism: https://www.mayoclinic.org/diseases-conditions/hypothyroidism/symptoms-causes/syc-20350284

• Mayo Clinic — Hyperthyroidism: https://www.mayoclinic.org/diseases-conditions/hyperthyroidism/symptoms-causes/syc-20373659

• Harvard Health Publishing: https://www.health.harvard.edu/a_to_z/hypothyroidism-a-to-z

• Kalra S, Bhattacharya S, Rawal P. Hepatocrinology. Med Sci (Basel). 2021;9(2):39. doi:10.3390/medsci9020039

• Piantanida E, Ippolito S, Gallo D, et al. The interplay between thyroid and liver: implications for clinical practice. J Endocrinol Invest. 2020;43(7):885-899. doi:10.1007/s40618-020-01208-6