Fatigue: Common Medical Causes and What Tests May Help#

Fatigue is a non-specific symptom, but persistent fatigue should not be normalized. It can be linked to sleep issues, stress, anemia, thyroid dysfunction, or blood sugar imbalance. If fatigue is ongoing or worsening, targeted testing is more useful than guessing.

Quick answer#

Short-term fatigue often improves with rest and routine correction, but fatigue lasting more than 2 to 3 weeks needs medical assessment. In clinical practice, diabetes and thyroid disorders are common reversible contributors.

You can explore other symptom pages from the symptoms hub.

Emergency signs (red flags)#

Seek urgent care if fatigue appears with:

• Chest pain or breathing difficulty
• New confusion, severe drowsiness, or fainting
• Black stools, bleeding, or persistent vomiting
• High fever with weakness and poor intake

Common causes (ranked)#

1. Sleep deprivation and high stress
2. Anemia and nutritional deficiency
3. Blood sugar dysregulation, including diabetes
4. Thyroid dysfunction
5. Ongoing infection or chronic inflammatory disease

Related pages: frequent urination, weight gain, and hair fall.

Suggested tests#

Initial tests are selected by history and exam. Common starting points:

• HbA1c when glucose problems are suspected
• Thyroid profile for endocrine causes
• CBC and selected nutritional tests as indicated

What you can do now (safe, general)#

• Normalize sleep and wake timing
• Keep regular meal timing and hydration
• Reduce alcohol and late caffeine
• Track fatigue pattern across workdays and weekends

For local test access, see HbA1c test Chennai and thyroid test Chennai.

When to see a doctor#

Consult if:

• Fatigue lasts beyond 2 to 3 weeks
• Daily function or concentration is clearly affected
• Associated symptoms include fever, weight change, appetite loss, or mood changes

FAQs#

Is fatigue always due to vitamin deficiency?#

No. Deficiency is one cause, but endocrine, metabolic, sleep, and mental health factors are also common.

Should I order all tests at once?#

Usually no. A clinician-led targeted approach is safer and more cost-effective.

Can fatigue occur with normal HbA1c?#

Yes. Fatigue has many causes, so normal HbA1c does not rule out other conditions.

References#

1. NHS - Tiredness and Fatigue (NHS, 2025)
2. CDC - Diabetes Symptoms (CDC, 2025)
3. NHS - Underactive Thyroid (NHS, 2025)