Can you die from hypothyroidism. Can Hypothyroidism Be Fatal? Exploring Severe Complications and Health Risks

28.08.202310.07.2023 by alexxlab

How does hypothyroidism affect overall health. What are the potential life-threatening complications of untreated hypothyroidism. Can proper management prevent severe outcomes in hypothyroid patients.

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Understanding Hypothyroidism: A Comprehensive Overview

Hypothyroidism is a condition characterized by an underactive thyroid gland, resulting in insufficient production of essential thyroid hormones. These hormones play a crucial role in regulating various bodily functions, including metabolism, growth, and development. While hypothyroidism is generally manageable with proper treatment, severe cases left untreated can lead to life-threatening complications.

The Thyroid Gland: A Small but Mighty Organ

Located in the front of the neck, the thyroid gland may be small, but its impact on the body is significant. It produces two primary hormones: thyroxine (T4) and triiodothyronine (T3). These hormones influence nearly every organ system, affecting:

Body temperature regulation
Weight management
Cardiovascular function
Reproductive health
Energy levels
Mood and cognitive function

When thyroid hormone levels are too low, the body’s processes slow down, leading to a range of symptoms and potential complications.

Cardiovascular Complications: The Heart of the Matter

One of the most serious potential complications of untreated hypothyroidism involves the cardiovascular system. Thyroid hormones have a direct impact on heart function and blood circulation.

How does hypothyroidism affect heart health?

Hypothyroidism can lead to several cardiac issues:

Bradycardia (slow heart rate)
Irregular heartbeats (arrhythmias)
Weakened pulse
Decreased cardiac output

Research has shown that severe hypothyroidism can reduce the volume of blood pumped by the heart in each beat by 30 to 50 percent. This significant decrease in cardiac output can strain the heart and potentially lead to heart failure if left untreated.

The Link Between Thyroid Hormones and Heart Failure

Low levels of triiodothyronine (T3) have been associated with an increased risk of heart failure. T3 plays a crucial role in maintaining healthy heart muscle function and regulating heart rate. When T3 levels are insufficient, the heart may struggle to pump blood effectively, potentially leading to congestive heart failure in severe cases.

Renal Function and Hypothyroidism: A Delicate Balance

The kidneys and thyroid gland have a complex interrelationship, with thyroid hormones playing a vital role in kidney function. Severe hypothyroidism can have significant impacts on renal health.

How does hypothyroidism affect kidney function?

Untreated hypothyroidism can lead to several renal complications:

Decreased blood flow to the kidneys
Reduced ability to excrete water
Impaired sodium absorption
Hyponatremia (low blood sodium levels)

These renal issues can be particularly dangerous, as they may lead to fluid imbalances and electrolyte disturbances throughout the body. In severe cases, this can result in life-threatening complications such as cerebral edema or cardiac arrhythmias.

Neurological Implications: When the Nervous System Slows Down

The nervous system is highly sensitive to thyroid hormone levels, and hypothyroidism can lead to various neurological complications if left untreated.

What neurological symptoms can hypothyroidism cause?

Severe hypothyroidism may result in:

Muscle weakness
Peripheral neuropathy
Breathing difficulties
Hoarseness
Impaired gait and balance
Speech problems
Increased risk of carpal tunnel syndrome

These neurological complications can significantly impact quality of life and, in extreme cases, may even become life-threatening if respiratory function is severely compromised.

Fertility and Reproductive Health: The Thyroid-Hormone Connection

Thyroid hormones play a crucial role in reproductive health for both men and women. Untreated hypothyroidism can have significant impacts on fertility and pregnancy outcomes.

How does hypothyroidism affect male fertility?

In men, low thyroid hormone levels can lead to:

Reduced sperm production
Abnormal sperm morphology
Decreased libido
Erectile dysfunction
Low testosterone levels

These factors can significantly impact a man’s ability to conceive and may require medical intervention to address.

Hypothyroidism and Female Reproductive Health

Women with hypothyroidism may experience:

Menstrual irregularities
Anovulatory cycles
Increased risk of infertility
Higher likelihood of miscarriage
Complications during pregnancy (e.g., preeclampsia, preterm birth)

Studies suggest that menstrual problems are three times more frequent in women with hypothyroidism compared to those with normal thyroid function. Additionally, women with autoimmune thyroid disorders may face an even higher risk of fertility issues.

Myxedema Coma: A Rare but Life-Threatening Complication

While rare, myxedema coma is perhaps the most severe and potentially fatal complication of untreated hypothyroidism. This medical emergency occurs when the body’s functions slow to a life-threatening degree due to extremely low thyroid hormone levels.

What are the symptoms of myxedema coma?

Myxedema coma is characterized by:

Profound hypothermia (low body temperature)
Altered mental status or coma
Severe bradycardia
Hypoventilation
Hypotension
Hyponatremia
Hypoglycemia

This condition requires immediate medical intervention and has a high mortality rate, even with treatment. Prompt recognition and aggressive management are crucial for survival.

Metabolic Disruptions: When the Body’s Engine Slows Down

Thyroid hormones are key regulators of metabolism, and hypothyroidism can lead to significant metabolic disturbances if left untreated.

How does hypothyroidism affect metabolism?

Severe untreated hypothyroidism can result in:

Decreased basal metabolic rate
Weight gain and difficulty losing weight
Impaired glucose metabolism and insulin resistance
Dyslipidemia (abnormal blood lipid levels)
Reduced thermogenesis (heat production)

These metabolic disruptions can contribute to an increased risk of obesity, type 2 diabetes, and cardiovascular disease. In extreme cases, the slowing of metabolic processes can contribute to the development of myxedema coma.

Prevention and Management: The Key to Avoiding Severe Complications

While the potential complications of untreated hypothyroidism can be severe, the good news is that most can be prevented or reversed with proper treatment and management.

How is hypothyroidism treated?

The primary treatment for hypothyroidism involves thyroid hormone replacement therapy, typically with levothyroxine. This synthetic form of thyroxine (T4) helps restore normal thyroid hormone levels and alleviate symptoms.

Effective management of hypothyroidism includes:

Regular monitoring of thyroid hormone levels
Adjusting medication dosages as needed
Addressing any underlying causes (e.g., autoimmune disorders)
Maintaining a healthy lifestyle to support overall thyroid function

With proper treatment, most people with hypothyroidism can lead normal, healthy lives and avoid the severe complications associated with the condition.

In conclusion, while hypothyroidism can potentially lead to life-threatening complications if left untreated, early diagnosis and appropriate management can significantly reduce these risks. If you experience symptoms of hypothyroidism or have concerns about your thyroid function, it’s crucial to consult with a healthcare professional for proper evaluation and treatment. By working closely with your healthcare team and adhering to recommended treatment plans, you can effectively manage hypothyroidism and maintain optimal health.

Complications of Hypothyroidism: Fertility, Weight and More

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Medically reviewed by Judith Marcin, M. D. — By Jyoti Madhusoodanan — Updated on August 16, 2019

The thyroid is a small gland in the front of the neck. It makes hormones that regulate growth and metabolism. These hormones affect nearly every body function. Thyroid hormones can influence:

body temperature
weight
cardiovascular health
fertility

Hypothyroidism occurs when the thyroid gland does not produce enough hormones. If your thyroid hormone levels are too low, you may have fatigue, digestive problems, sensitivity to cold temperatures, and menstrual irregularities. The condition can be managed with medication. If left untreated, though, hypothyroidism can lead to many complications. These include heart problems, nerve injury, infertility and in severe cases, death.

Your thyroid hormone level can impact your cardiovascular health. You may have a slow pulse, abnormal heartbeats, and weakened pulse.

One study found that hypothyroidism can decrease the volume of blood pumped out by the heart in each beat by 30 to 50 percent. Low levels of the triiodothyronine (T3) thyroid hormone are also associated with heart failure.

Fortunately, most cardiac complications related to hypothyroidism can be treated. This involves using the proper medication to correct your thyroid function.

Serious hypothyroidism can lower the kidney’s function. This is often due to decreased blood flow to the kidneys. You may have less ability to excrete water and absorb sodium. As a result, blood levels of sodium may be unusually low.

Replacing thyroid hormones can fix these complications. But if extremely low hormone levels persist, recovery from these renal problems can take longer.

Hypothyroidism can cause problems with the nervous system, such as muscle weakness or nerve injury. These can lead to:

breathing difficulties
hoarseness
trouble walking
trouble talking
pain in the hands and feet

People with untreated hypothyroidism may also be more prone to carpal tunnel syndrome.

Hypothyroidism reduces fertility in both men and women. Thyroid hormones regulate the metabolism of sex hormones, which control the production of sperm and eggs. In men, low levels of thyroid hormones have been linked to erectile dysfunction, abnormal sperm shape, and decreased libido. Men with hypothyroidism often also have low levels of testosterone.

Evidence from multiple studies suggests that menstrual problems are three times more frequent in women with hypothyroidism. Variation in flow and irregular menstruation are the most common symptoms. Women with autoimmune thyroid disorder are also more likely to have infertility.

Studies suggest that not enough thyroid hormones during pregnancy may cause problems. It can increase the risk of a miscarriage or other complications, like preeclampsia or preterm birth.

If you have hypothyroidism, tell your doctor if you’re pregnant or planning to become pregnant. That way, proper treatment can begin as soon as possible. You may need to adjust the dose of thyroid medication frequently during pregnancy, so regular thyroid tests are important.

If you notice symptoms of hypothyroidism, talk to your doctor. Being proactive and treating hypothyroidism early can help avoid any major complications.

Last medically reviewed on February 23, 2017

How we reviewed this article:

Healthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. We avoid using tertiary references. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

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Medically reviewed by Judith Marcin, M.D. — By Jyoti Madhusoodanan — Updated on August 16, 2019

Older adults with hypothyroidism face elevated risk of death

Older adults with hypothyroidism face elevated risk of death | Endocrine Society

Press Release

Washington, DC
December 13, 2019

Increased risk does not impact older adults with subclinical hypothyroidism

While older adults with hypothyroidism face an elevated risk of death, individuals with subclinical hypothyroidism, a milder form of underactive thyroid, did not face the same risk, according to new research published in the Endocrine Society’s Journal of Clinical Endocrinology & Metabolism.

Hypothyroidism occurs when the body produces too little thyroid hormone. Thyroid hormone controls a person’s metabolism and affects the way the body uses energy, consumes oxygen and regulates temperature. The condition occurs more often in women and people over the age of 60.

“Our meta-analysis is the first to evaluate and confirm the association between hypothyroidism and mortality, specifically focusing on an older population,” said Carol Chiung-Hui Peng, M.D., of the University of Maryland Medical Center Midtown Campus in Baltimore, Md., and one of the study’s authors.

“Our analysis found individuals with hypothyroidism aged 60 years or older were 26 percent more likely to die from all causes than individuals in the same age range who did not have the thyroid condition,” said co-author, Huei-Kai Huang, M.D., of Hualien Tzu Chi Hospital and Tzu Chi University in Hualien, Taiwan.

The researchers reviewed the results of 27 published articles including over 1.1 million older individuals. Although hypothyroidism was associated with all-cause mortality risk, the studies did not find a higher incidence of cardiovascular mortality. Interestingly, studies published in Asia and North America were associated with increased all-cause mortality in the hypothyroid population, while those published in Europe and Oceania were not. Among individuals with hypothyroidism who were 80 years old or older, the researchers found no increased risk of all-cause or cardiovascular mortality.

The mortality difference was not seen in older patients with milder forms of thyroid disease. This study provides further evidence to help guide management of hypothyroidism in older adults.

“In accordance with guidelines, our findings imply that individuals with subclinical hypothyroidism—those who have milder thyroid dysfunction—may not benefit from being treated with synthetic thyroid hormone,” said Kashif M. Munir, M.D., associate professor in the division of endocrinology, diabetes and nutrition at the University of Maryland School of Medicine in Baltimore, Md., and another of the study’s authors. “However, treatment should be considered in individuals diagnosed with hypothyroidism, given increased all-cause mortality. ”

Other authors include: Tou-Yuan Tsai, M.D., of Dalin Tzu Chi Hospital in Chiayi, Taiwan; Yu-Kang Tu, D.D.S., M.Sc., Ph.D., of National Taiwan University Hospital and School of Dentistry, National Taiwan University in Taipei, Taiwan; Shu-Man Lin, M.D., of Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, in Hualien, Taiwan; Rachel Huai-En Chang, M.D., M.P.H., M.B.A., of Johns Hopkins Bloomberg School of Public Health in Baltimore; Sheng-Lun Kao, M.D., of Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation and Tzu Chi University in Hualien, Taiwan; and Ching-Hui Loh, M.D., Ph.D., of Hualien Tzu Chi Hospital in Hualien, Taiwan.

The study was not supported by external funding.

The manuscript, “Association of Hypothyroidism and Mortality in the Elderly Population: A Systematic Review and Meta-Analysis,” was published online, ahead of print.

About Endocrine Society

Endocrinologists are at the core of solving the most pressing health problems of our time, from diabetes and obesity to infertility, bone health, and hormone-related cancers. The Endocrine Society is the world’s oldest and largest organization of scientists devoted to hormone research and physicians who care for people with hormone-related conditions.

The Society has more than 18,000 members, including scientists, physicians, educators, nurses, and students in 122 countries. To learn more about the Society and the field of endocrinology, visit our site at www.endocrine.org. Follow us on Twitter at @TheEndoSociety and @EndoMedia.

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What is hypothyroidism and how to deal with it > Rubric Medicine in Samara

Age-related changes are often accompanied by weakness, drowsiness, weight gain, slowness of thinking and speech. Bad mood and obnoxiousness become the norm.

“Old age,” relatives wave their hands. However, this condition is often based on endocrine problems. They can be corrected, if not avoided.

Systemic changes

Hypothyroidism is a pathology of the endocrine system in which the function of the thyroid gland deteriorates and the level of hormone production decreases. As a result, the body experiences a lack or decrease in the action at the cellular level of the two main biologically active substances – triiodothyronine T3 and thyroxine T4. Their action extends to all tissues of the body, and without their products, human existence is simply impossible. There are systemic, that is, affecting all organs, changes in the work of the body.

Thyroid hormones regulate energy metabolism in organ cells. Their deficiency leads to the fact that the tissues are not saturated with oxygen in the required volume, the synthesis of various energy-dependent cellular enzymes necessary for the normal functioning of the cell is disrupted. In the case of a neglected disease, mucinous, or mucous edema occurs – myxedema.

The skin and subcutaneous tissue are primarily affected. If you press with your finger, then even the fossa does not remain: there are no redness, blanching, depressions or prints. The face becomes puffy, mask-like. The features are coarsened, the chin area increases in size, facial expressions are simplified. The mouth is constantly ajar, breathing is difficult, the tongue is enlarged. Due to the swelling of the vocal cords, the voice becomes coarse, hoarseness, hoarseness, cough, shortness of breath appear.

Due to metabolic disorders in the body, the work of the cardiovascular system, brain, and digestive system deteriorates, changes occur in bones and muscles. In older people, the manifestations may be different, depending on the severity, but in any case, they will affect the usual way of life. Often a person begins to gain weight quickly. The situation is complicated by the fact that the disease is not so easy to diagnose.

– Hypothyroidism may not be detected for a long time. This is due to the gradual, imperceptible onset of the process, the satisfactory well-being of patients with mild and moderate disease, as well as the erased symptoms – they are often found in other diseases. Therefore, most people believe that they are simply overworked, that they are depressed. Pregnant women attribute the malaise to their position and are not particularly worried, but in vain, says Lyudmila Sharonova, Candidate of Medical Sciences, Associate Professor of the Department of Endocrinology and Geriatrics of the Samara State Medical University. – Early hypothyroidism can be noticed only if you undergo a systematic diagnosis in the laboratory. That is, in order not to miss the onset of the disease, it is important not to neglect preventive examinations, and, of course, contact specialists at the first alarming symptoms.

If the problem is ignored

The prevalence of hypothyroidism is about 1%, among women of reproductive age – 2%, in the elderly increases to 10%. The disease occurs even in children. But still, the elderly are mostly at risk.

— After the age of 60, it is mandatory to undergo timely diagnostics. If you carefully monitor the state of the body, you can respond to changes in time and immediately begin the manipulations necessary for recovery. And vice versa: if you ignore the disease, serious health problems are inevitable, says Lyudmila Sharonova.

The consequences can be the most severe. In children, the activity of the central nervous system is disturbed, mental retardation develops – up to oligophrenia and cretinism. The child lags behind in growth, sexual development, is prone to frequent infectious diseases with a long chronic course. During pregnancy, the disease is fraught with various anomalies in the development of the fetus and the birth of a baby with functional thyroid insufficiency. Men and women with hypothyroidism may be infertile.

In hypothyroidism, severe immune disorders occur, which are manifested by frequent infections. Finally, the most severe complication is coma. It usually occurs in lonely, poorly cared for elderly patients with long-term, untreated hypothyroidism. The situation is aggravated by concomitant diseases: infections, injuries, hypothermia. Treatment is carried out in intensive care units and resuscitation with the appointment of thyroid hormones and glucocorticosteroids, correction of hemodynamic and electrolyte disorders. But, unfortunately, according to statistics, up to 80% of patients die with the development of myxedema coma.

Symptoms of hypothyroidism in the elderly:

constant feeling of weakness, high fatigue, drowsiness, apathy;
weight gain, overweight, increased cholesterol;
bad mood, depression, insomnia;
dry skin and hair;
slow heart rate;
constant feeling of cold;
swelling of the face and body;
constipation.

Who is at risk:

people over 60;
patients with autoimmune diseases: diabetes mellitus, rheumatoid arthritis, vasculitis, multiple sclerosis, psoriasis, systemic lupus erythematosus and others;
people who have undergone thyroid surgery or whose parents and grandparents suffered from thyroid disease;
population of regions where iodine deficiency or elevated levels of radiation have been recorded.

How to treat

Coping with the disease is real. Modern pharmacology is capable of artificially synthesizing the thyroid hormone L-thyroxine. It successfully replaces its natural counterpart. In most cases, the normalization of the general condition of a patient with hypothyroidism begins already in the first week of starting the drug. Complete disappearance of clinical symptoms usually occurs within a few months. In the elderly and debilitated patients, the reaction develops more slowly. Patients with cardiovascular diseases need to carefully select the dose of the drug, since excessive intake increases the risk of angina pectoris and atrial fibrillation.

“If hypothyroidism occurs against the background of other diseases, then the main pathology should be treated first,” recommends Lyudmila Sharonova. – The work of the thyroid gland in this case is also stabilized. Symptoms of hypothyroidism caused by taking certain medications are eliminated after they are discontinued. If the cause of hypothyroidism is a lack of iodine intake with food, the patient is prescribed iodine-containing drugs, eating iodized salt, and seafood.

Prevention again

It is easier to deal with any illness at an early stage.

— The prognosis for hypothyroidism depends on the timeliness of the started replacement therapy. The quality of life of patients taking compensatory treatment usually does not decrease. Moreover, they have practically no restrictions, except for the need for daily intake of L-thyroxine. Prevention of hypothyroidism consists in good nutrition with sufficient intake of iodine, explains Lyudmila Sharonova.

Products containing iodine:

eggs;
whole cow’s milk;
meat – pork and beef;
buckwheat and oatmeal, millet;
feijoas, persimmons, apples, bananas, cranberries;
sorrel, spinach, lettuce;
garlic, beans, peas, lentils;
bread baked from rye and wheat flour of the second grade.

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Damage to various organs and systems in hypothyroidism uMEDp

Hypothyroidism is the most common thyroid dysfunction. Since thyroid hormones are involved in the regulation of metabolism, differentiation and functioning of body tissues, hypothyroidism can cause changes in all organs and systems. The article discusses these changes in detail.

Table. Skin changes in hypothyroidism

Hypothyroidism is a clinical syndrome caused by hypofunction of the thyroid gland and characterized by a reduced content of thyroid hormones in the blood serum [1]. The prevalence of primary overt hypothyroidism in the population is 0.2-2%, subclinical – up to 10%. This disease is associated with high overall and cardiovascular mortality [2].

The most common cause of primary hypothyroidism is chronic autoimmune thyroiditis. In rare cases, the disease develops during the treatment of thyrotoxicosis.

The clinical manifestations of hypothyroidism are varied, since almost all organs and systems are affected.

Skin changes with hypothyroidism may be due to:

direct action of thyroid hormones on the skin and its components through receptors. Thyroid hormone receptors have been identified both in epidermal keratinocytes and in the dermis and hair follicles;
deficiency of thyroid hormones in other tissues;
autoimmune diseases associated with hypothyroidism.

Among the histological changes in the skin, there are thinning and hyperkeratosis of the epidermis, accumulation of glycosaminoglycans, in particular hyaluronic acid, in the dermis.

The consequence of insufficiency of thyroid hormones in the epidermis is dryness and roughness of the skin, especially the extensor surfaces of the extremities. Dry skin can also be the result of reduced secretion of exocrine glands and sweating.

The accumulation of glucosaminoglycans and carotene leads to swelling of the dermis and yellowing of the palms, soles and nasolabial folds. Hypothyroidism is characterized by mucinous edema of the skin and subcutaneous fat, which spreads to other tissues. As a result, puffiness and coarsening of facial features, pronounced periorbital edema, an increase in the tongue, along the edges of which teeth marks remain. Macroglossia and swelling of the vocal cords cause blurred, slow speech, a decrease in the timbre of the voice, and the appearance of hoarseness.

In addition, changes in the skin appendages are noted: a decrease in the rate of hair growth, diffuse / focal alopecia, loss of the lateral third of the eyebrows, thinning, fragility and striation of the nail plate.

Insufficiency of thyroid hormones in other tissues leads to a decrease in the rate of metabolic processes. As a result, thermogenesis decreases and, as a result, reflex compensatory vasoconstriction. With a decrease in skin perfusion, the skin becomes pale and cold to the touch.

Since the most common cause of hypothyroidism is chronic autoimmune thyroiditis, changes in the skin may be the result of other autoimmune pathologies. These are alopecia areata, pernicious anemia, bullous pemphigoid, dermatitis herpetiformis, systemic lupus erythematosus, scleroderma, lichen sclerosus, vitiligo, eczema.

The most common skin manifestations of hypothyroidism are presented in the table [1].

Thyroid hormones directly and indirectly affect cardiovascular system . They have a positive inotropic and chronotropic effect, increasing myocardial oxygen demand. In hypothyroidism, there is an increase in peripheral vascular resistance by 30–50%, a decrease in left ventricular contractility, cardiac output by 30–50%, circulating blood volume, an increase in the time of diastolic myocardial relaxation, bradycardia and diastolic arterial hypertension [1]. Since, along with a decrease in myocardial contractility, peripheral vascular resistance increases, mean arterial pressure usually remains within the normal range. There may be a decrease in systolic blood pressure and an increase in diastolic blood pressure with low pulse pressure.

Diastolic arterial hypertension is diagnosed in 20–35% of patients with hypothyroidism. However, after replacement therapy with levothyroxine sodium and compensation for hypothyroidism, the indicators usually normalize.

Hypothyroidism disrupts the metabolism of homocysteine, a product of methionine demethylation, which is considered an independent risk factor for the development of atherosclerosis [3].

Other risk factors for the development of cardiovascular pathology in this disease include hypercholesterolemia, hypercoagulability, diastolic hypertension, diastolic dysfunction of the left ventricle, a decrease in the level of vascular relaxation factors, an increase in the level of C-reactive protein [4].

Hypothyroidism is characterized by edematous syndrome due to increased capillary permeability and transudation of fluid and albumin into interstitial and other spaces (for example, the pericardial sac, pleura). When analyzing the results of electrocardiography in patients with myxedematous heart, bradycardia, low voltage, negative T wave, impaired intraventricular conduction with the development of blockade of the left and right branches of the His bundle are detected [3].

Thus, with hypothyroidism, the risk of developing coronary heart disease and heart failure increases.

Changes in the respiratory system are more often associated with obesity associated with hypothyroidism. The degree of damage depends on the severity of hypothyroidism and varies from mild dyspnea to severe life-threatening respiratory failure.

In patients with hypothyroidism, the vital capacity of the lungs, the partial pressure of oxygen in the blood may slightly decrease, and the alveolar-arterial oxygen gradient may increase. Surfactant deficiency due to hypothyroidism can cause microatelectasis, which is not visualized on x-ray. Weakness of the respiratory muscles in hypothyroidism also contributes to impaired lung function.

Severe hypothyroidism is associated with hypoxia and hypercapnia.

Thyroid hormone deficiency is associated with neonatal respiratory distress syndrome – thyroid hormones are involved in surfactant production and fetal lung maturation.

Excretory system. Hypothyroidism directly or indirectly affects kidney function. Secondary arterial hypertension due to a decrease in cardiac output and an increase in systemic vascular resistance leads to a decrease in kidney perfusion, filtration capacity and glomerular filtration rate (GFR). Patients also have reduced reabsorption in the tubules of the kidneys, increased excretion of sodium and decreased excretion of potassium. Plasma renin activity, serum levels of aldosterone, atrial natriuretic peptide may decrease. These indicators are normalized during replacement therapy with levothyroxine sodium [5].

Due to the increased sensitivity of the kidneys to vasopressin, a decrease in GFR and a decrease in the flow of primary urine into the tubular system of the kidneys, hyponatremia develops in some cases [1].

With prolonged hypothyroidism, an increase in the level of creatinine in the blood serum is observed, which normalizes after compensation for hypothyroidism.

In patients with chronic kidney disease, hypothyroidism impairs kidney function. Therefore, with an inexplicably sharp decrease in GFR, an assessment of the level of thyroid-stimulating hormone is recommended.

Due to myopathy and reduced clearance, patients have elevated levels of myoglobin and creatine kinase. Cases of rhabdomyolysis and acute renal failure have been described [6]. Hypothyroidism is characterized by a violation of purine metabolism.

Decreased renal blood flow and filtration can lead to hyperuricemia. The latter is detected in 30% of patients with hypothyroidism. 7% of patients develop gout [7].

However, kidney pathology can result not only from thyroid dysfunction, but also from autoimmune nephropathy and proteinuria [8].

Gastrointestinal tract. Hypothyroidism reduces appetite, which, despite a decrease in metabolism, prevents the development of obesity. The increase in body weight in such patients is primarily due to fluid retention.

The most common symptom of hypothyroidism is decreased motility of the gastrointestinal tract. There is a decrease in both electrical and motor activity of the esophagus, stomach, small and large intestine [1]. Violation of the motor activity of the esophagus can lead to dysphagia, there is a slowdown in the evacuation of food from the stomach and passage through the intestines. A decrease in the motor function of the intestine can be accompanied by both mild obstipation and paralytic ileus and pseudo-obstruction. Characterized by obstipation, not amenable to laxative therapy. These changes may be the result of autonomic neuropathy, impaired transmission of nerve impulses in myoneural junctions, intestinal ischemia and myopathy [3].

Absorption of nutrients is usually not impaired. However, in severe hypothyroidism, cases of malabsorption have been described, which may be a consequence of myxedematous infiltration of the intestinal mucosa [3].

Liver function in hypothyroidism is usually unchanged. At the same time, a moderate increase in serum lactate dehydrogenase, aspartate aminotransferase and creatine phosphokinase is possible [1].

It has been established that hypothyroidism contributes to the development of gallstone disease. Among the predisposing factors are hypercholesterolemia, gallbladder dyskinesia and reduced bilirubin excretion [9]. Patients with hypothyroidism due to chronic autoimmune thyroiditis are five times more likely to develop celiac disease [10].

The prevalence of primary biliary cirrhosis among patients reaches 5–20% [11].

Chronic viral hepatitis C and interferon therapy are associated with an increased incidence of positive antibodies to thyroperoxidase and the development of primary hypothyroidism [12].

Hypothyroidism has various effects on hematopoiesis, peripheral blood cells and coagulation system . 25–50% of patients with hypothyroidism suffer from anemia [1].

Anemia can be physiological – the result of a decrease in the need for oxygen in peripheral tissues. A decrease in circulating plasma volume may be associated with a decrease in the mass of red blood cells (some patients have a hematocrit below 35%) [13].

Anemia in hypothyroidism is due to the inhibition of erythropoiesis and a decrease in the concentration of erythropoietin in the blood serum.

If patients have normal levels of iron, serum iron, vitamin B ₁₂ and folic acid, the life expectancy of erythrocytes, normochromic, normocytic anemia develops, which is leveled a few weeks or months after the start of therapy with levothyroxine sodium [13].

Some patients with hypothyroidism suffer from iron deficiency anemia. The reasons for its development may be low absorption of iron in the gastrointestinal tract and excessive blood loss, especially with menorrhagia. It has been shown that iron absorption in hypothyroidism is reduced, however, this indicator increased in response to thyroid hormone therapy. Against the background of such treatment, an increase in the level of hemoglobin was recorded, while it was more significant if iron preparations were taken simultaneously [1].

Approximately 10% of patients with hypothyroidism due to autoimmune thyroiditis are diagnosed with pernicious anemia. Approximately 12% of patients with pernicious anemia have overt hypothyroidism. 15% have subclinical hypothyroidism. That is why it is advisable to screen for hypothyroidism among patients with pernicious anemia. Patients with hypothyroidism and pernicious anemia should receive treatment with both thyroid hormones and vitamin B ₁₂ [1].

The level of leukocytes and the leukocyte formula in such patients are usually not changed.

In hypothyroidism, various disorders of hemostasis have been described. And although it is assumed that the cause is a deficiency of thyroid hormones, the main mechanisms of such disorders have not yet been established. Patients may experience a slight appearance of hematomas, an increase in bleeding time after dental and other procedures or minor injuries, menorrhagia [13].

The most frequent changes in the blood coagulation system are considered to be a decrease in the plasma concentration of coagulation factor VIII and an increase in partial thromboplastin time [14]. The content of platelets is often within the normal range, however, the number of megakaryocytes in the bone marrow may be reduced. The average platelet volume also remains normal.

The hemorrhagic syndrome is completely reversible in the treatment with thyroid hormones, the levels of clotting factors are also restored.

Some patients with hypothyroidism are more sensitive to the action of aspirin – after taking it, the duration of bleeding increases. In addition, data were obtained on profuse bleeding after taking the drug in patients with uncompensated hypothyroidism. Therefore, patients with hypothyroidism are advised to prescribe aspirin with caution [15].

Patients with uncompensated hypothyroidism are resistant to the hypoprothrombic effects of warfarin, since the clearance of coagulation factors is slowed down in them, and therefore dose adjustment of the drug may be required. After the appointment of hormone replacement therapy, the dose of warfarin returns to the original.

Nervous system. Neuropathy in hypothyroidism is manifested by paresthesia and painful dysesthesia. Patients may present with symptoms of mononeuropathy, polyneuropathy, and cranial nerve neuropathy.

The most common manifestation of mononeuropathy is carpal tunnel syndrome. It develops due to compression of the median nerve in the carpal tunnel by edematous tissues. Patients complain of numbness, tingling and pain in the nerve innervation area – the palmar surface of the thumb, index, middle and medial edges of the ring fingers. The connection between hypothyroidism and mononeuropathies developed as a result of compression of the posterior tibial nerve and the lateral saphenous femoral nerve has been proven. Peripheral polyneuropathy is rare.

Isolated neuropathies of the II, V, VII, and VIII cranial nerves have been described, leading to hearing loss, sensorineural hearing loss, and tinnitus. With hypothyroidism, ataxia and poor coordination of movements can also be observed due to impaired blood supply and degenerative changes in the cerebellum.

Cognitive impairments, especially in the older age group, can be manifested by lethargy, deterioration of short-term memory, and decreased attention.

Less commonly, primary hypothyroidism due to chronic autoimmune thyroiditis is associated with encephalopathy. The combination of these diseases came to be called Hashimoto’s encephalopathy. Seizures can complicate the course of myxedema coma and Hashimoto’s encephalopathy.

Perhaps the development of depression, delirious states (myxedematous delirium), bradyphrenia.

In addition, with hypothyroidism, paroxysms of panic attacks are observed with periodic attacks of tachycardia.

Musculoskeletal system. Myopathy is a common symptom of hypothyroidism. Patients complain mainly of proximal muscle weakness, stiffness, convulsions, and myalgia. Less often, myopathy is accompanied by an increase in muscles (pseudohypertrophy), painful cramps, and stiffness. In the blood serum, an increased concentration of creatine phosphokinase and myoglobin is determined. Histological changes in muscle fibers are nonspecific, atrophy or loss of type 2 muscle fibers is detected, and areas of necrosis and regeneration may be present [1].

Hypothalamo-pituitary system. Hyperproduction of thyrotropin-releasing hormone by the hypothalamus in hypothyroxinemia increases the release of not only thyroid-stimulating hormones, but also prolactin by the adenohypophysis. This, with primary hypothyroidism, can lead to the development of hyperprolactinemic hypogonadism. Hyperprolactinemic hypogonadism is manifested by oligoopsomenorrhea or amenorrhea, galactorrhea, secondary polycystic ovaries [16].