Obesity and Endocrine System: Links Between Thyroid, High Blood Pressure, and Heart Disease
**What is the relationship between obesity and thyroid function?**
The thyroid gland is an important endocrine gland in the human body. Thyroid hormones secreted by the thyroid gland promote the breakdown and metabolism of fats, increase oxygen consumption, heat production, and adenosine triphosphate (ATP) synthesis in many tissues, and simultaneously promote the synthesis of proteins, ribonucleic acid (RNA), and deoxyribonucleic acid (DNA) in many cells, thereby promoting human growth and development. Insufficient thyroid hormones-hypothyroidism-can reduce tissue breakdown and metabolism, decrease heat production, and reduce the production of proteins and nucleic acids. This leads to the accumulation of metabolic products in tissues, especially substances called mucin and mucopolysaccharides, which can be widely deposited in various tissues and organs, including subcutaneous tissue, causing "myxedema." Patients may experience weight gain, especially noticeable swelling in the face, eyelids, and anterior tibial regions. This myxedema differs from obese edema, which leaves a pitting edema; it generally leaves no indentation after pressure, and the skin loses elasticity and becomes rough. Patients may also experience cold intolerance, slowed reactions, slower speech, and significantly decreased memory-clinical symptoms of hypometabolism.
Therefore, hypothyroidism is often mentioned in the diagnosis of obesity. However, although hypothyroidism may cause weight gain, it is not the same as obesity. It is important to differentiate between the two to avoid delaying the diagnosis and treatment of the disease.
What is the relationship between obesity and high blood pressure?
The incidence of hypertension is very high among obese individuals, and the contributing factors are:
(1) **Genetic factors**
Genetics also plays a role in the development of hypertension in obese individuals. Recent studies have found that hypertension is often accompanied by hyperinsulinemia, including some hypertensive patients with normal weight. The direct or indirect effects of hyperinsulinemia on blood vessel walls have a significant impact on the development of hypertension. These patients often have a familial predisposition to the disease.
(2**) Changes in hemodynamics**
An increase in the oxygen difference between arteries and veins, especially during activity, is a significant factor. This is because obese patients have a large increase in adipose tissue, leading to a corresponding increase in blood volume and peripheral resistance in the arterioles. This, in turn, increases cardiac output to ensure blood supply to peripheral tissues. The resulting arteriole sclerosis contributes to the development of hypertension.
(3) **Endocrine changes**
Obese individuals may experience increased adrenal gland levels, imbalances in the renin-angiotensin-aldosterone system, hyperinsulinemia, increased thyroid hormone levels, elevated adrenaline concentrations (exceeding 30% of those in non-obese individuals of the same age), elevated aldosterone levels, and increased norepinephrine secretion, all of which can lead to elevated blood pressure.
**(4) The Influence of Social Environmental Factors**
If obese individuals dislike exercise, have a good appetite, and enjoy sweets and fatty foods, their excessive energy intake coupled with insufficient energy expenditure easily leads to obesity. Excessive fat accumulation increases the burden on the heart, potentially causing high blood pressure.
What is the relationship between obesity and heart disease?
According to reports, the incidence of coronary heart disease among obese individuals is 34.1%. The main mechanism by which obesity causes heart disease is:
① Excessive fat accumulation increases circulating blood volume, leading to increased psychological stress and elevated blood pressure.
② Coexisting abnormal lipid metabolism and high-calorie diet, with intake exceeding consumption, cause hyperlipidemia, leading to coronary atherosclerosis and fat deposition in myocardial cells, thickening of the ventricular wall, and decreased myocardial compliance.
③ The accompanying increase in blood sugar and blood lipids increases blood viscosity, weakens the oxygen-carrying capacity of red blood cells, and leads to insufficient oxygen supply to myocardial cells.
④ Obese people often dislike exercise, and excessive obesity also limits their activity levels, which leads to weakened or insufficient coronary collateral circulation and decreased cardiac compensatory capacity.
Therefore, some scholars have pointed out that a weight gain of more than 30% above the standard weight is a signal that one will develop coronary heart disease within 10 years, and that coronary heart disease in obese patients is more difficult to treat and more dangerous than that in non-obese patients.
Therefore, it can be said that weight loss is, in a sense, also a way to prevent coronary heart disease.
**What is the relationship between obesity and stroke recovery?**
Obese individuals are more prone to stroke and experience slower recovery from stroke for several reasons: First, obesity often leads to higher blood lipids and blood viscosity, making it more difficult to completely clear blood vessels during stroke treatment. Second, the excessive weight of obese individuals slows nerve conduction, resulting in insufficient nerve nutrition and the effects of gravity, thus hindering limb recovery. Third, psychological factors in obese individuals can cause a natural contraction response to limb pain, making it difficult to relax tense skin. Furthermore, patients who are generally sedentary may find their activity levels significantly reduced after a stroke, further impeding limb recovery. In conclusion, to facilitate a faster recovery for obese stroke patients, it is essential to strengthen medication treatment, adjust their diet, and engage in manageable functional exercises to aid recovery.
**What is the relationship between obesity and adrenal cortex function?**
The adrenal gland is an important endocrine gland in the human body, consisting of two main parts: the cortex and the medulla.
The adrenal cortex has three zonas, each with different secretory functions: mineralocorticoids, glucocorticoids, and sex corticosteroids. The hormones secreted by the zona glomerulosa cells primarily participate in salt (sodium) metabolism, hence they are called mineralocorticoids. The hormones secreted by the zona fasciculata cells are the largest in quantity and have a wide range of effects, participating in the three major metabolic processes in the body, primarily carbohydrate metabolism; therefore, they are called glucocorticoids. The hormones secreted by the zona reticularis cells are structurally and functionally similar to those secreted by the human gonads (testes in males and ovaries in females), hence they are called sex corticosteroids.
Glucocorticoids promote protein breakdown and inhibit its synthesis, causing the released amino acids to migrate to the liver, enhancing gluconeogenesis, and antagonizing insulin, inhibiting insulin binding to its receptors. This reduces peripheral glucose utilization, decreases fat and muscle tissue, and lowers glucose uptake, leading to elevated blood sugar. Glucocorticoids increase the breakdown of fat tissue in the limbs, while increasing fat synthesis in the abdomen, face, shoulders, and back, a condition known as "central obesity"-Cushing's syndrome. Glucocorticoids can also cause water intoxication in individuals with adrenal insufficiency, leading to water retention. Furthermore, they increase the number of red blood cells, platelets, and neutrophils in the blood, while decreasing the number of lymphocytes and eosinophils, and also have some effects on nerves, muscles, and blood vessels.
Sexual corticosteroids are mainly aldosterone, which can promote the retention of water and electrolytes in the body.
Androgens can promote the development and growth of internal and external genitalia, promote male secondary sexual function, promote protein synthesis, and develop muscles.
Adrenal medullary hormones have a significant effect on blood pressure and blood vessels.
The main measurements for understanding adrenal function are 17-ketosteroids and 17-hydroxysteroids. In patients with simple obesity, the production and metabolism of adrenal glucocorticoids are increased, leading to increased urinary excretion of 17-hydroxysteroids and 17-ketosteroids. Hirsutism and amenorrhea in obese patients are associated with adrenocortical hormone secretion. However, if the dexamethasone (low-dose) suppression test and diurnal cycle changes are normal, it suggests that adrenal cortical function associated with obesity is not hyperactive. Hyperactive adrenocortical function manifests as the aforementioned "central obesity."
**★Obese individuals are prone to osteoarthritis.**
The causes of osteoarthritis in obese individuals are multifaceted. Excess weight increases the pressure on weight-bearing articular cartilage, leading to greater wear and tear and changes in the internal structure of the joints. The heavier the body weight and the thicker the subcutaneous fat, the more severe the joint damage, especially for weight-bearing joints such as the knees and feet. Osteoarthritis is also related to metabolic disorders and ischemic bone malnutrition caused by arteriosclerosis. Diabetic osteoarthritis is closely related to diabetic neuropathy and trauma. Neuropathy causes loss of deep and superficial sensation and impaired joint movement reflexes, weakening or eliminating sensation and pain, leading to excessive joint load and a lack of protection against trauma, resulting in joint damage. Gouty osteoarthritis is closely related to overeating in obese patients. Long-term excessive intake of high-protein, high-purine foods increases exogenous uric acid levels beyond the kidneys' excretion, leading to hyperuricemia. Uric acid deposits as urate crystals in joints and cartilage, causing inflammation and allogeneic reactions at the affected sites, resulting in joint damage.
Weight gain inevitably puts a heavy burden on bones and joints. Many obese people suffer from osteoarthritis at a young age, which is related to metabolic disorders caused by obesity.
There are three main types of osteoarthritis in obese individuals: ① Obesity accompanied by degenerative osteoarthritis, with an incidence rate of 12%-43%, and obese individuals account for 12%-45% of osteoarthritis patients; ② Obesity accompanied by diabetic osteoarthritis, with an incidence rate of 1%-2%, and diabetes accounts for approximately 6%-7% of osteoarthritis patients; ③ Obesity accompanied by gouty osteoarthritis, with an incidence rate of 15%-30%, and obese individuals account for 50% of gouty osteoarthritis patients.
Weight loss therapy is an important measure to control osteoarthritis. Local treatment helps to relieve pain, and medicated bath therapy is beneficial for both weight loss and disease treatment.