Sometimes, no matter how many pairs of wool socks you wear, your feet just can't seem to warm up. If you're relatively healthy, chances are the cause of your cold feet is likely something harmless. But there are serious health conditions that can make your feet forever chilled.

The simplest reason is a lack of warmth. Another common reason is poor circulation, when not enough blood is getting to your feet to keep them warm. This can be caused by a sedentary lifestyle if you spend much of your day sitting at a desk. You can remedy that by getting up more frequently and moving around throughout the day. Circulation issues can also be caused by underlying health problems.

Here's a look at some of the more serious reasons you may be suffering from feet that always seem to be cold:

Raynaud's disease

Raynaud's disease typically causes your fingers and toes to feel cold and numb, usually when they're exposed to cold temperatures or even stress. With this condition, the small arteries that bring blood to your skin become narrow, limiting circulation in some areas, according to the Mayo Clinic.

Raynaud's disease (also called Raynaud's syndrome or phenomenon) is more common in women and in people who live in colder climates.

In addition to feeling cold, skin usually changes colors. Affected areas turn white, then blue and later turn red when they warm up. As skin warms, you may experience a prickly, painful, burning sensation.

In mild cases, you can treat Raynaud's by dressing in layers and wearing heavy socks to stay warm. In some cases, your doctor may suggest medication to help with circulation. Some over-the-counter cold medications and prescription heart medications can make the condition worse, so check with your doctor if you're having symptoms.

Hypothyroidism

An under-active thyroid — or hypothyroidism — is when your thyroid gland doesn't make enough of the hormone that helps keep many of the body’s systems running smoothly. The symptoms are subtle and come on slowly, reports WebMD. "You might mistake them for aging or stress."

Hypothyroidism symptoms include sensitivity to cold, as well as fatigue, weight gain and memory problems. Your skin might feel cool, dry and itchy.

Your doctor can diagnose thyroid problems with a blood test. Hypothyroidism is treated with a synthetic thyroid hormone taken daily.

Anemia

Anemia is when you don't have enough healthy red blood cells to carry oxygen throughout your body. The most common symptom of anemia is feeling weak and tired, according to the National Institutes of Health, but other symptoms include cold hands and feet, as well as dizziness, shortness of breath, headache and pale skin.

Treatment depends on the type, cause and severity of anemia, but it often includes dietary changes and supplements including iron, folic acid, vitamin C, and/or vitamin B12.

Peripheral arterial disease

Also known as peripheral vascular disease, atherosclerosis or hardening of the arteries, this common condition occurs when cholesterol, fat or some other substances build up in the walls of the arteries. These deposits form hard structures called plaques and cause the walls of the arteries to narrow.

It can take years for the walls of the arteries to harden and years for symptoms to show. Typically, the earliest signs are leg discomfort, pain and cramping, according to the Cleveland Clinic. Other symptoms include cool skin in the feet and redness or pain in the feet and toes.

Talk to your doctor if you are having symptoms. Treatment depends on how far the disease has advanced and can include lifestyle changes and medication.

Hyperhidrosis

Hyperhidrosis is excessive sweating that is frequent or constant and typically occurs in the hands, feet and armpits. Heavy sweating seems like it would have nothing to do with cold feet. But hyperhidrosis is overactivity of the sympathetic nervous system, according to Cedars-Sinai.

That leads to narrowing of arteries, so while hands and feet are sweating, they are also getting less blood flow, making them cold in addition to wet. Prescription medications are often used to treat the condition.

Diabetic nerve damage

Diabetic peripheral neuropathy is a type of nerve damage that can happen to people with diabetes who have chronically high blood sugar. Symptoms include numbness, tingling, burning, pain and a feeling of coldness in the feet, legs or hands. Symptoms are typically worse at night, says Diabetes Monitor.

Avoid soaking your feet in hot water to warm them up (you may not realize the water is too hot). Instead, always wear warm socks, even to bed, and use an electric blanket at night. It's also a good idea to exercise regularly and wiggle your toes and feet when sitting to help with circulation.

Other nerve damage

In addition to nerve damage from diabetes, you can also experience peripheral neuropathy as a result of an injury or some other underlying medical condition. This nerve pain, which can give the sensation of cold feet, can be a result of a vitamin deficiency, kidney or liver disease, infection, metabolic issue, or even an exposure to some sort of toxin, according to the Mayo Clinic. The condition may also be genetic and in some cases the cause is never uncovered.

Smoking

Circulation issues caused by smoking can result in cold feet. One such rare, but serious, complication includes Buerger's disease, which affects blood vessels in the arms and legs. The blood vessels swell, which can prevent blood flow and can cause clots to form, according to the CDC. Early symptoms include cold hands and feet, but can lead to tissue damage, pain and painful sores, ulcers and even gangrene.

Just a footnote

Incidentally, did you ever wonder where the expression “getting cold feet” comes from? “Cold feet” as an expression connotes loss of courage, such as when a performer gets cold feet right before he goes on stage to thousands of waiting fans or a bride gets cold feet before her wedding day. Linguists trace it back to possibly English playwright Ben Jonson in 1605 or German author Fritz Reuter in an 1862 novel. The earliest use of it in the English language likely dates back to writer Stephen Crane in his 1896 book, “Maggie: A Girl of the Streets” in which he writes, “I knew this was the way it would be. They got cold feet.”

No matter where the phrase comes from and no matter the underlying cause, cold feet can be uncomfortable, and in some cases, a sign that something more serious is going on. Be sure to check with your doctor if you think this might be the case.

And put on some warm socks.

This story first appeared on MNN in July 2013. It has been updated to reflect more current information.

Mary Jo DiLonardo Mary Jo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.