Yawn! I feel SO tired. Is something wrong?

Q: I know it’s the holiday rush, but suddenly I’m feeling overwhelmingly tired, even if I get plenty of sleep. What could this be, and what will my doctor look for?

A: Sudden fatigue can have many causes, but the pattern of your fatigue can help determine its source. For instance, if you wake up fairly rested but even minimal activity is exhausting, you may have an underlying medical problem. If you wake up with low energy that persists throughout the day, there’s a chance you may be clinically depressed.

The medical causes of fatigue include the obvious as well as the obscure. Clearly, an overwhelming viral infection such as the flu will exhaust you so that the simple act of getting out of bed is difficult. But fatigue can also be an early sign of a more chronic problem. Here are some scenarios to consider:

Out of iron
Women often feel they have “run out of steam” because they are anemic, or lack the iron needed to maintain the proper function of their blood cells. We tend to get used to our periods, even if they are heavy, and often discount the fact that with each cycle there is a substantial loss of blood and iron.

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If the iron in your diet (including any standard vitamins you may take) is not sufficient to compensate for this loss, you may feel tired and run-down even if you maintain a “normal” red blood count (hemoglobin and hematocrit).

Studies show that women with low iron who add appropriate iron supplements often notice less fatigue within four weeks.

Thyroid problems
If your thyroid becomes under-active (hypothyroidism), your first symptom may be lethargy. Hypothyroidism occurs in up to 10 percent of women. Hormonal fluctuations, especially after pregnancy and during perimenopause, can cause autoimmune “attacks” on the thyroid, destroying its ability to appropriately direct your metabolic processes.

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If you are feeling lethargic — especially if you also have weight gain, cold intolerance, constipation and dry skin — you may have hypothyroidism. This is easily diagnosed with a blood test of thyroid stimulating hormone, or TSH. If the TSH is too high, it means the actual secretion of thyroid hormone is too low. (This may sound counter-intuitive, but we are testing the hormone secreted by the pituitary gland, which tells the thyroid what to do. When the thyroid is not complying, the pituitary gland secretes more TSH in an effort to force the thyroid to do so.)

Therapy is simple — replacement with thyroid hormone. Hypothyroidism is a chronic condition, so you will probably be on thyroid therapy indefinitely.

Multiple sclerosis
Another autoimmune possibility is multiple sclerosis. Half of women with MS describe fatigue as the feature that most impairs their quality of life. Early diagnosis and improved therapies can make a big difference in the symptoms and progression.

Diabetic issues
The onset of diabetes may also be heralded by fatigue. This can be diagnosed with a fasting blood sugar test.

Other autoimmune problems
Other autoimmune diseases causing fatigue include lupus (which is often followed by joint pain and rash), rheumatoid arthritis (usually accompanied by morning stiffness and joint pain) and polymyositis (associated with muscle weakness).

Infections and tiredness
Chronic infection in any part of the body also can lead to exhaustion. These infections include pneumonia, hepatitis, parasitic infections of the gastrointestinal tract, heart infections, and infections caused by AIDS. So blood tests for liver function and white blood cell count should be done, along with a test for nonspecific inflammation (sedimentation rate).

Heart problems
An early sign of heart disease in women may be fatigue. A study of more than 500 women who had heart attacks showed that 70 percent recalled unusual fatigue more than a month before their heart attack. So if you have underlying cardiovascular risk — if you smoke, or have high blood pressure, diabetes, abnormal cholesterol or a family history of heart disease — sudden onset of fatigue should be considered a cardiac warning and you should have an electrocardiogram or stress echocardiogram.

Pills making you tired?
Medications can have fatigue as a side effect, especially when first taken. The “I’m exhausted” instigators include antihistamines, blood pressure medications, sedatives, steroids, diuretics, pain medications and antidepressants.

Don’t discount depression
Speaking of antidepressants, if your fatigue is constant throughout the day, this may be due to depression. One fourth to one third of all women will experience at least one episode of clinical depression during their lives. And the holidays may trigger a new or repeat bout due to the stress of unrealistic expectations, difficult family situations, money and gifting woes, as well as the winter absence of sunshine and too little physical activity.

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There are no blood tests that will diagnose this. Your doctor will have to rely on your medical history and exclude other illness. (And if the antidepressant medication that is supposed to cure fatigue instead causes further fatigue, speak to your doctor about a different dose or a different medication.)

A workup of fatigue should include:

• A complete medical history
• A physical exam to check your lymph nodes, heart, lungs and thyroid
• An electrocardiogram and or echocardiogram to rule out heart disease
• Blood tests that include a complete blood count (CBC), iron level, thyroid test, sedimentation rate, Chem-20 panel, (which tests for kidney and liver function), anti-nuclear antibody titer (which tests for autoimmune disorders), fasting lipid panel and fasting blood sugar.

Finally, if indicated, a pregnancy test should be done. Early pregnancy can cause a sense of total exhaustion.

Dr. Reichman’s Bottom Line: Don’t make excuses about why you are so tired. Acute fatigue is often a warning of serious medical or psychological problems and warrants appropriate testing and care.

Dr. Judith Reichman, the “Today” show's medical contributor on women's health, has practiced obstetrics and gynecology for more than 20 years. You will find many answers to your questions in her latest book, "Slow Your Clock Down: The Complete Guide to a Healthy, Younger You," published by William Morrow, a division of HarperCollins.

PLEASE NOTE: The information in this column should not be construed as providing specific medical advice, but rather to offer readers information to better understand their lives and health. It is not intended to provide an alternative to professional treatment or to replace the services of a physician.

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