If you keep a blanket, sweater, or space heater near you at all times — or find yourself frequently adjusting the thermostat — you may have a cold intolerance. You might even find yourself shivering at times, which is a natural response and the body's way of generating its own heat, Ana Carolina Silva [1], DO, a board-certified endocrinologist and internist in Florida and New Jersey, told POPSUGAR.

However, while some people may just have a lower body temperature, for others a persistent feeling of being cold [2] could be a sign of something more serious. Dr. Silva explained that thermoregulation, or the ability to maintain normal body temperature [3], is a complex process that involves multiple organ systems. This means that there are a handful of underlying conditions that can cause someone to experience cold sensations or generally struggle to stay warm.

Ahead, experts break down some of the most common reasons you may be cold. While feeling like you need to layer up can be normal, if you're concerned you have a cold intolerance — or unsure of what steps to take next — it's best to talk to your doctor, explained Magdalena Cadet [4], MD, a clinical rheumatologist and autoimmune diseases specialist in New York.

Thyroid Disorders

One of the most common reasons for persistently feeling cold is an underactive thyroid gland [5], otherwise known as hypothyroidism. "Your thyroid is a butterfly-shaped gland that sits on the front portion of your neck," Dr. Silva said. "It is essentially your body's thermostat, and if it's set too low, you may feel overall very cold."

Other symptoms of an underactive thyroid may include fatigue, coarse hair, brittle nails, abnormally heavy periods, weight gain, and hair loss, Dr. Cadet noted.

Neuropathy

Neuropathy (nerve damage) can be brought on by several things, the biggest being poorly controlled diabetes. "Nerves send signals to the brain that allow you to feel sensation," Dr. Silva said. She explained that, when these signals are disrupted by nerve damage, people may feel strangely cold or experience other symptoms like pain, numbness, and tingling.

Vascular Conditions

According to Dr. Silva, there are two vascular diseases that can cause cold sensations: venous stasis and vasoconstriction. In venous stasis, cooled and deoxygenated blood becomes pooled instead of travelling through the veins back to the lungs, which can cause specific parts of the body to feel cold. On the flip-side, vasoconstriction is when small, narrow blood vessels become constricted, decreasing the flow of warm blood to areas like the hands and feet.

Pituitary or Hypothalamic Dysfunction

The pituitary gland is known as the "master gland," because it determines when other glands in the body work and rest. "A pituitary dysfunction can introduce an array of hormonal disturbances and a cold intolerance," Dr. Silva said. Located just above the pituitary is the hypothalamus, the portion of the brain that regulates body temperature. Dr. Cadet stressed that the hypothalamus is crucial to our health: "It helps control hormone release like the thyroid stimulating hormone [and assists in] the regulation of blood flow and body fat." The hypothalamus can be disrupted by trauma, tumors, and even medication.