Unexplained weight loss can be a sign of an underlying medical condition, especially if it is significant (more than 5% of body weight within 6–12 months) and unintentional. Identifying the cause is essential for appropriate treatment.
Possible Causes of Unexplained Weight Loss
1. Endocrine Disorders
- Hyperthyroidism: Overactive thyroid increases metabolism.
- Diabetes (Type 1 or Type 2): High blood sugar levels cause unintentional weight loss.
- Adrenal Disorders: Conditions like Addison’s disease can lead to weight loss.
2. Gastrointestinal Disorders
- Malabsorption: Conditions like celiac disease or Crohn’s disease impair nutrient absorption.
- Ulcers or Gastritis: Stomach pain or nausea may reduce appetite.
- Liver or Pancreatic Disease: Impairs digestion and metabolism.
3. Chronic Infections
- Tuberculosis (TB): Causes significant weight loss along with other symptoms like fever and night sweats.
- HIV/AIDS: Affects the immune system and can lead to wasting syndrome.
- Parasitic Infections: Parasites can rob the body of nutrients.
4. Cancer
- Weight loss is a common early symptom of many cancers, including:
- Lung cancer
- Pancreatic cancer
- Gastrointestinal cancers (e.g., stomach, colon)
5. Mental Health Conditions
- Depression: Can reduce appetite or interest in food.
- Anxiety: Heightened stress may lead to weight loss.
- Eating Disorders: Conditions like anorexia nervosa may not always be initially apparent.
6. Neurological Disorders
- Parkinson’s Disease or Dementia: May impair swallowing or reduce interest in eating.
7. Autoimmune Diseases
- Rheumatoid Arthritis: Inflammation increases energy expenditure.
- Lupus: Causes systemic inflammation and appetite loss.
8. Substance Abuse
- Alcohol, illicit drugs, or overuse of certain medications (e.g., stimulants) can lead to poor appetite or nutrient absorption.
9. Medications
- Side effects of medications (e.g., chemotherapy, antidepressants) can suppress appetite or cause nausea.
10. Aging
- Loss of muscle mass (sarcopenia), reduced appetite, or other age-related conditions may lead to weight loss.
Testing for Unexplained Weight Loss
1. Initial Evaluation
- Medical History: Includes questions about diet, lifestyle, medications, and stress.
- Physical Exam: Checks for signs like swollen lymph nodes, thyroid abnormalities, or gastrointestinal issues.
2. Laboratory Tests
- Blood Tests:
- Complete Blood Count (CBC): Detects anemia or infection.
- Thyroid Function Tests (T3, T4, TSH): Checks for hyperthyroidism.
- Blood Glucose: Screens for diabetes.
- Liver and Kidney Function Tests: Identifies organ dysfunction.
- Nutritional Markers:
- Vitamin levels (e.g., B12, D) and electrolytes.
- Inflammatory Markers:
- C-reactive protein (CRP) or erythrocyte sedimentation rate (ESR).
3. Imaging Studies
- X-rays or CT Scans: Look for tumors, infections, or organ abnormalities.
- Endoscopy/Colonoscopy: Investigates gastrointestinal issues.
4. Specialized Tests
- HIV or TB Testing: If infection is suspected.
- Autoimmune Panels: For conditions like lupus or rheumatoid arthritis.
- Cancer Screening: Biopsies or tumor markers based on symptoms.
When to See a Doctor
- Weight loss >5% of body weight in 6–12 months without explanation.
- Accompanied by symptoms like fatigue, pain, fever, or digestive issues.
- Persistent appetite changes or gastrointestinal problems.
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