What are the risk factors for osteoporosis, especially in postmenopausal women with a family history of the condition, low body weight, and certain medical conditions like rheumatoid arthritis, thyroid disorders, and gastrointestinal diseases?

Risk Factors for Osteoporosis

Osteoporosis risk factors are divided into modifiable and non-modifiable categories, with the strongest predictors being older age, low body weight, prior fracture history, and low bone mineral density. 1, 2

Non-Modifiable Risk Factors

Demographic Factors

• Older age (>70 years) is the single most important risk factor, with fracture risk increasing substantially with each decade 1, 2
• Female sex confers significantly higher risk than male sex, with 1 in 3 women versus 1 in 5 men over age 50 experiencing osteoporotic fractures 2
• White or Asian race carries higher risk compared to other ethnic groups 1
• Maternal history of hip fractures indicates genetic predisposition 1
• Late menarche is associated with lower peak bone mass 1

Clinical History

• Prior fragility fracture is one of the two strongest predictors; women with a prevalent vertebral fracture are 2-4 times more likely to experience a new vertebral fracture and twice as likely to experience a hip fracture 1
• Low bone mineral density (BMD) is the other strongest predictor; each 1 SD decrease in hip BMD increases hip fracture risk 2.6-fold 1

Modifiable Risk Factors

Body Composition and Nutrition

• Low body weight (<70 kg or BMI <20-25 kg/m²) is a strong predictor and should trigger screening at age 60 rather than 65 1
• Weight loss (>10% from usual adult weight) significantly increases risk 1
• Low calcium intake (inadequate intake below 1,200 mg/day) 1
• Low vitamin D intake (inadequate intake below 400-800 IU/day) 1

Lifestyle Factors

• Physical inactivity (no regular walking, stair climbing, weight-bearing, or resistance exercise) 1
• Current cigarette smoking increases fracture risk 1, 2
• Excess alcohol consumption (>2 drinks per day) increases fracture probability 1, 2
• Excessive caffeine intake contributes to bone loss 1

Hormonal and Endocrine Factors

• Low estrogen levels in women, including postmenopausal status, premature ovarian failure, or clinical estrogen deficiency with oligomenorrhea/amenorrhea 1
• Hypogonadism in men, particularly from androgen deprivation therapy (pharmacologic or orchiectomy), which is a strong predictor 1
• Hyperthyroidism and thyroid replacement therapy (though data in men are insufficient) 1
• Primary hyperparathyroidism impairs bone quality 1
• Hypercortisolism is associated with impaired bone quality 1

Medications

• Oral corticosteroid use (≥5 mg prednisone daily for ≥3 months) is a major risk factor 1
• Long-acting sedatives increase fall-related fracture risk 1

Medical Conditions

• Rheumatoid arthritis is associated with increased osteoporosis risk 2, 3
• Inflammatory bowel disease contributes to bone loss 2
• Chronic liver disease increases fracture risk 2
• Chronic kidney disease and renal osteodystrophy impair bone quality 1, 2
• Gastrointestinal malabsorption prevents adequate calcium and vitamin D absorption 1
• Diabetes mellitus (particularly type 2) impairs bone quality despite sometimes normal BMD 1
• Spinal cord injury is a moderate predictor of both low BMD and fracture 1
• History of anorexia nervosa may impair achievement of peak bone mass 1

Fall-Related Risk Factors

• History of falls increases fracture probability independent of BMD 1
• Poor balance and impaired visual function contribute to fall risk 1
• Muscle weakness and osteosarcopenia increase both fall and fracture risk 1
• Impaired mental status increases fall-related fractures 1

Special Populations Requiring Evaluation

Premenopausal Women and Younger Men

Any fragility fracture in a premenopausal woman or man <50 years indicates impaired bone strength and requires comprehensive evaluation, as the majority of such fractures are due to underlying disease 1

Key factors to assess include:

• Gonadal status (estrogen deficiency with low LH/FSH/estradiol or primary ovarian failure with high LH/FSH and low estradiol) 1
• Current and past body weight, including history of eating disorders 1
• Diseases affecting bone formation, resorption, or mineralization 1

Breast Cancer Patients

Women with breast cancer face additional osteoporosis risk beyond standard factors, with vertebral fracture risk 4.7 times higher in those with localized disease and 22.7 times higher with soft tissue metastasis (without bone metastasis) compared to women without cancer 1

Clinical Implications for Screening

Screening should begin at age 65 for all women, but at age 60 for women with increased risk (particularly low body weight <70 kg or prior fracture history) 1. For men, screening is recommended when multiple risk factors are present, particularly age >70 years, low BMI, weight loss, corticosteroid use, or prior fracture 1.