Don’t expect a quick solution, or even an accurate diagnosis, if you’re suffering from fatigue. You might have to see a lot of experts before you get the right answer.

Reason: Even though doctors check for cortisol deficiency as a sign of adrenal insufficiency, also known as Addison’s disease, a common cause of fatigue, they may neglect to investigate the one hormone that is an early indicator of the disease.

The adrenal glands, located just above the kidneys, produce more than 50 hormones, including cortisol (the “stress” hormone) and aldosterone (which maintains the body’s sodium balance). Cortisol levels often are tested because low levels indicate Addison’s disease and cortisol deficiency can be life-threatening, while low aldosterone usually is not. But it could be a low level of aldosterone that is making you tired…

WARNING SIGNS

If you have low aldosterone, fatigue probably will be the first symptom—but it might take months before you recognize it. Reason: Fatigue and other symptoms come on gradually. It’s common for patients to get accustomed to how they feel.

Helpful: Measure your blood pressure at home if you’re experiencing persistent fatigue. The natural increase in blood pressure that occurs in the doctor’s office, known as “white-coat hypertension,” can give a reading that’s artificially high. If you have low aldosterone, your blood pressure could be as low as 90/60. (Normal is about 120/80.)

Another key symptom of low aldosterone is the intense craving for salt. Patients with low aldosterone lose excessive amounts of sodium in their urine.

WHAT HAPPENS

Addison’s disease is caused by damage to the outer layer of the adrenal glands. The damage usually is caused when the immune system “mistakenly” attacks the glands. If left untreated, Addison’s disease can be life-threatening.

Important: If you are suffering from persistent fatigue and have other symptoms of low aldosterone, ask your doctor to test for aldosterone as well as cortisol. Aldosterone that measures 5 ng/dL or lower could be causing your symptoms even if your cortisol is normal. Aldosterone can be measured with a standard blood test.

HOW TO TREAT IT

If you have low aldosterone…

Eat more salt. Patients with low aldosterone and fatigue often feel better immediately when they consume more salt. Don’t worry about getting excessive salt—the advice to follow a low-sodium diet applies only to those at risk for high blood pressure (hypertension). If your aldosterone is low, you want to raise your blood pressure, not lower it.

Recommended: Get an extra one to two teaspoons of salt a day. You might need to increase the amount slightly during the summer, when you lose more sodium in perspiration.

Drink licorice tea. Licorice (the natural root, not the candy) doesn’t increase aldosterone, but it makes it more active in the body. Patients with relatively mild fatigue may notice an increase in energy when they drink a few cups of licorice tea daily.

You can make your own licorice tea by steeping about two tablespoons of fresh, peeled licorice root in a cup of simmering water for about an hour. You also can buy tea bags that contain licorice root (available at most health- food stores).

Eat grapefruit. It has the same effect as licorice. You can buy grapefruit supplements, but they’re expensive. The fresh fruit works just as well—and will give you extra fiber, nutrients, etc.

Caution: Grapefruit and grapefruit juice alter the metabolism of many types of medications, so if you are taking other medications, talk with your doctor.

Ask about medication. Patients who have severe fatigue and/or dizziness usually need to take the synthetic form of aldosterone, fludrocortisone (Florinef). Available by prescription, it’s much safer than the cortisol that’s used to treat full-fledged Addison’s disease. Cortisol, especially if given to patients who are not cortisol-deficient, can lead to weight gain, diabetes and decreased immunity and should not be stopped abruptly.

Bonus: It’s safe to stop taking synthetic aldosterone if symptoms improve and to start taking it again if you need to. Unlike cortisol, dose changes don’t have to be “tapered” when stopping the medication.

I usually start patients on half a 0.1- milligram pill, taken in the morning. After a week or two, the dose can be increased to one pill. The main side effects are headache and leg swelling, but these often decrease over time—and many patients have no side effects at all.

Also helpful: A blood pressure–raising medication, such as midodrine (ProAmatine). Patients who combine this with fludrocortisone and who increase their consumption of salt often report a rapid improvement in energy and a reduction in dizziness and cognitive changes.