Estrogen and Bone Health - An Overview

Introduction

Bone is a tissue in which bone turnover (bone formation and resorption) takes place throughout a lifetime. Cells involved in bone turnover are osteoblasts and osteoclasts. Osteoblasts form bone, whereas osteoclasts resorb bone. Estrogen is a sex hormone that helps in bone formation, thereby promoting the activity of osteoblast cells.

How Does Estrogen Affect Bone Health?

Bone is in a healthy state when the body constantly replaces the old bone with new bone. The bone consists of a matrix of proteins and minerals which make the bone strong and flexible. Bone contains osteocytes that maintain the matrix of the bone. Estrogen regulates bone metabolism and is essential for bone health.

What Happens When There Is a Low Level of Estrogen?

Estrogen is produced by ovaries in females and has a role in sexual development and fertility. In males, testosterone is converted to estrogen, which supports overall health and some reproductive functions.

Estrogen levels vary in a lifetime, generally in females after menopause and after giving birth. In such conditions, bone density decreases, and they become fragile and brittle leading to fractures. Estrogen affects the cells in the bone, leading to decreased quality of the bone structure and less new bone formation.

There is a complex relationship between estrogen and bone health. They involve;

• Immune System: Researchers thought estrogen affected bone homeostasis by regulating the immune system

• Effects on Bone Cells: Osteocytes, osteoblasts, and osteoclasts are affected.

• Oxidative Stress: When there is an imbalance between free radicles and antioxidants causes oxidative stress.

• Sema 3A Protein: As people age, levels of estrogen and Sema 3A protein (present in osteocytes) decrease, which results in bone weakening.

What Are the Symptoms of Low Estrogen?

Low levels of estrogen do not show symptoms generally. As females get to menopause may show irregular periods. Other symptoms include;

• Bone fractures due to osteoporosis.

• Infertility in males and females.

• Decreased libido.

• Erectile dysfunction.

• Heart disease.

• Increased cholesterol levels.

What Are the Causes of Low Levels of Estrogen?

Low levels of estrogen are mainly caused by the following factors;

• Age: Estrogen levels increase in the puberty stage among both males and females. Estrogen levels fluctuate in females during reproductive age. Its level starts to decline during menopause and perimenopause (the first stage of menopause).

• Health Conditions: In females, health issues related to ovaries decrease the levels of estrogen. In males, conditions that are related to cause low testosterone bring down the levels of estrogen. Some of the conditions are:

• Polycystic ovary syndrome.

• Thyroid disorders.

• Low functioning pituitary gland.

• After giving birth.

• Breastfeeding.

• Low body weight.

• Turner syndrome (congenital condition).

• Chemotherapy.

• Primary ovarian insufficiency.

What Are the Effects of Low Estrogen Levels?

Estrogen plays a role in many bodily functions. Effects of low estrogen include;

• Irregular Periods: Estrogen regulates the menstrual cycle in females. Low levels may affect cycles of menstruation.

• Libido: In males, sperm count and health may be affected, thereby affecting libido.

• Osteoporosis: Low levels of estrogen affect bone health, thereby affecting the strength of bone, leading to the fracture of bones.

• Pain During Intercourse: Dryness of the vagina is caused when there is a low level of estrogen present, as estrogen helps lubricate the vagina.

• Urinary Tract Infection: Low levels of estrogen cause vaginal tissue thinning, thereby increasing the risk of urinary tract infections.

• Mood Changes: Low estrogen may cause depression among females as hormonal fluctuations are more common in certain stages of life.

• Weight: Studies have shown that increased weight can be seen in the case of low estrogen levels as they have an influence on metabolism.

How Does Estrogen Regulates Bone Health or Bone Mass?

Estrogen acts on two receptors called estrogen receptor-alpha ( ERα), and estrogen receptor-beta (ERβ). Alpha is important for bone metabolism. These receptors are found in cells of bone and bone marrow. Osteoprotegerin (OPG) is a mediator of the action of estrogen on bone. OPG is a receptor activator of the NF-kB ligand ( RANKL) system. RANKL is a cytokine responsible for the differentiation of osteoclasts. OPG is a receptor for RANKL that binds RANKL leading to the inhibition of osteoclastogenesis. RANKL acts through RANK (present in the cell membrane of osteoclasts and osteoclast precursor cells). Studies showed that when there are the absence of RANK or RANKL leads to osteoporosis. If OPG is deficient, excessive bone resorption and severe osteoporosis can be observed. Estrogens have two types of effects on long bones. At high concentrations, it promotes epiphyseal closure and stops further growth. The absence of estrogen is related to unfused growth plates and less growth.

How to Diagnose Low Levels of Estrogen?

It can be diagnosed using the following tests;

• Blood Test: Helps to know levels of estrogen hormones in the blood. For females who menstruate, estrogen levels vary. In these, doctors may suggest a test at a particular point in the cycle.

• Thyroid Function Test: Further blood tests like thyroid function tests are to be done.

• Scan: Scans of the ovaries in females may be done.

What Are the Treatments for Low Estrogen Levels?

If a person has fewer symptoms need not take any treatment. If symptoms are more, then the person may need medical help. Treatment depends on symptoms, cause, and the person’s treatment goals.

• Hormone Replacement Therapy (HRT): HRT reverses the levels of estrogen and other hormones. Sometimes doctors may give both estrogen and progesterone. HRT can be given as an injection, vaginally, topically, or orally. The lowest dose is always recommended. HRT may not be safe for all. People having a history of stroke, blood pressure, or heart attack may be advised not to take HRT.

• Estrogen Therapy: Only estrogen is given, like vaginal cream (containing estrogen) can be given to thinning vaginal tissue.

• Managing Symptoms: Additional treatments can be given based on symptoms.

• Based on Medical Conditions and Drugs: If any medications causing estrogen levels to drop are being taken, then other treatments are to be followed.

• Maintaining a Normal Weight: Attaining a normal weight is important as it solves many problems.

• Exercise: Along with taking a good diet, doing exercise regularly can help bone strength and levels of estrogen as well.

• Intake of Soy: Studies have shown that taking soy improves levels of estrogen.

• Vitamin D: This helps in preventing osteoporosis.

Conclusion

Estrogen is a hormone that not only affects the sex organs but also affects various organs such as the brain, heart, and bones. Low levels of estrogen can cause irregular periods, mood changes, osteoporosis, etc. Knowing in detail about its effects is crucial to avoid many problems. Seeking help from the doctor and taking preventive measures may also help avoid diseases. Early diagnosis is always better to treat the underlying condition effectively.