Key points
Many causes are easy to check. Some are found with blood tests, some on examination, and many are treatable: hypothyroidism, for example, is easy to diagnose and treat with levothyroxine, although some people still have symptoms (Chaker L Lancet 2017. PMID 28336049).
Feeling cold: common in hypothyroidism. Cold intolerance is among the most common symptoms of thyroid hormone deficiency in adults (Chaker L Lancet 2017. PMID 28336049).
Iron in iron-deficiency anemia. In a small study of 10 women with iron-deficiency anemia, body temperature in 28 °C water was lower than in healthy people, and a course of iron improved it (Beard JL Am J Clin Nutr 1990. PMID 2239756).
Primary Raynaud's is common. It affects about 5% of people (Garner R BMJ Open 2015. PMID 25776043); among 639 such patients, 12.6% developed a secondary disease over about 4 years (Spencer-Green G Arch Intern Med 1998. PMID 9521223).
One symptom is not a diagnosis. No single symptom of hypothyroidism is reliable, so even a slight suspicion is a reason to get a blood test (Carlé A Eur J Endocrinol 2014. PMID 25305308).
6 causes at a glance
- Hypothyroidism — the thyroid gland makes too little hormone.
- Low iron and anemia.
- Raynaud's phenomenon — attacks of spasm in the small blood vessels of the fingers.
- Eating too little.
- Narrowing of the leg arteries — more common in smokers, in people with diabetes and with age.
- Vitamin B12 deficiency — not feeling cold, but numbness that is sometimes mistaken for cold.
In frosty weather everyone's hands get cold; it is worth looking into when they feel cold all the time, even in the warmth.
1. Hypothyroidism
Thyroid hormones set the pace of metabolism and heat production. When they are low, a person may feel cold; this often comes with fatigue, sluggishness, weight gain, constipation and dry skin (Chaker L Lancet 2017. PMID 28336049).
But symptoms are misleading. A Danish study compared 140 people with newly diagnosed overt autoimmune hypothyroidism with 560 healthy people: the most common complaint was fatigue (81%), but neither the presence nor the absence of any single symptom helped decide who needed a test (Carlé A Eur J Endocrinol 2014. PMID 25305308).
2. Low iron and anemia
In a study of 10 women with iron-deficiency anemia, 8 with depleted iron stores but no anemia, and 12 healthy people, after 100 minutes in 28 °C water body temperature was lower with anemia — 36.0 vs 36.2 °C. A course of iron corrected the anemia and improved body temperature (Beard JL Am J Clin Nutr 1990. PMID 2239756).
3. Vitamin B12 deficiency
Feeling cold with B12 deficiency has not been studied, but a lack of it damages the nerves (Devalia V Br J Haematol 2014. PMID 24942828). Numbness and tingling in the feet are sometimes described as “my feet are cold” — this is a reason to check B12. More in the article on B12 deficiency.
4. Raynaud's phenomenon
In the cold or with emotional stress, the fingers suddenly turn white, then blue, and then red. According to a review of 33 studies (33,733 people), primary Raynaud's, not linked to another disease, occurs in 4.85% of people (the review's estimate ranges from 2 to 9%). The odds are higher in women (1.65-fold), with a family history, smoking and migraine (Garner R BMJ Open 2015. PMID 25776043).
Sometimes Raynaud's is secondary — the first sign of a connective tissue disease. In a review of 639 people with primary Raynaud's followed for about 4 years on average, such a disease developed in 12.6%. It was best predicted by capillaroscopy — examining the small blood vessels at the base of the nail under magnification: with abnormal capillaries the disease developed in 47%, with antinuclear antibodies in 30% (Spencer-Green G Arch Intern Med 1998. PMID 9521223).
5. Eating too little and low weight
In a study of 48 healthy overweight people (4 groups), those who ate 25% fewer calories for six months had a drop in body temperature, and their energy expenditure fell more than expected from weight loss (Heilbronn LK JAMA 2006. PMID 16595757). There are no data on feeling cold specifically with low weight; on a strict diet it is worth reviewing your nutrition.
6. Narrowed leg arteries
With smoking, diabetes and age, plaques build up in the leg arteries, and less blood reaches the feet. A typical sign is calf pain when walking that goes away at rest. According to a review of 34 studies (112,027 people), in high-income countries narrowing of the leg arteries (peripheral artery disease) affects about 5% of people aged 45–49 and 18–19% of those aged 85–89; smoking raises the odds 2.7-fold, diabetes 1.9-fold (Fowkes FG Lancet 2013. PMID 23915883).
The check is simple: the doctor compares blood pressure at the ankle and at the arm (the ankle-brachial index); 0.90 or lower indicates narrowed arteries (Fowkes FG Lancet 2013. PMID 23915883).
Which tests to discuss with your doctor
Thyroid-stimulating hormone (TSH). The main test for hypothyroidism; if it is abnormal, free T4 (thyroxine) is added. Reference ranges depend on the laboratory. Why TSH alone is sometimes not enough — in the article on TSH.
Ferritin with C-reactive protein. Ferritin shows iron stores but rises with inflammation, so it is checked together with C-reactive protein (CRP). According to the World Health Organization (WHO), deficiency is ferritin below 15 µg/L (15 ng/mL) in apparently healthy adults, and below 70 µg/L (70 ng/mL) with inflammation (WHO 2020. PMID 33909381). More in the article on ferritin.
Complete blood count. Hemoglobin and red blood cells show anemia; large red blood cells are a clue to B12 deficiency.
Vitamin B12 if you have numbness. Reference ranges depend on the laboratory; deficiency is often defined as a level below 148 pmol/L (200 pg/mL), borderline as 148–221 pmol/L (200–300 pg/mL) (Allen LH Am J Clin Nutr 2009. PMID 19116323). If the result is borderline but signs of deficiency are clear (numbness, unsteady walking), the British guideline advises the doctor not to delay treatment (Devalia V Br J Haematol 2014. PMID 24942828).
If your calves hurt when walking, if you are over 65, or over 50 and smoke or have diabetes, discuss the ankle-brachial index (Gornik HL Circulation 2024. PMID 38743805), and if secondary Raynaud's is suspected, capillaroscopy and antinuclear antibodies.
What the studies showed
| What was studied | Participants | Result |
|---|---|---|
| Symptoms of hypothyroidism, 2014 | 140 with overt autoimmune hypothyroidism, 560 healthy | No single symptom is reliable on its own |
| Cooling and iron, 1990 | 10 women with anemia, 8 with depleted stores, 12 healthy | With anemia, body temperature was lower (36.0 vs 36.2 °C); iron improved it |
| Primary Raynaud's, review, 2015 | 33 studies, 33,733 people | Prevalence 4.85% (2 to 9%); more common in women |
| Outcome of primary Raynaud's, 1998 | 639 people, about 4 years of follow-up | Secondary disease in 12.6% |
| Cutting calories by 25%, 2006 | 48 overweight people, 4 groups | Body temperature fell |
| Narrowing of the leg arteries, 2013 | 34 studies, 112,027 people | In high-income countries: 5% at 45–49, 18–19% at 85–89; smoking — odds ×2.7 |
Not everything is equally proven: in 8 women with depleted iron stores but no anemia, the response to cooling did not differ from healthy people, but the sample was small — this means “an effect was not shown”, not “there is no effect” (Beard JL Am J Clin Nutr 1990. PMID 2239756).
Who should be more careful
- A suddenly cold, pale and painful arm or leg — call an ambulance (Björck M Eur J Vasc Endovasc Surg 2020. PMID 31899099).
- Small sores or wounds on the fingertips — see a doctor promptly.
- Numbness, tingling or unsteady walking — get B12 checked without delay: early treatment helps avoid nerve damage.
- Calf pain when walking that goes away at rest — a planned visit to the doctor.
- Feeling cold together with fatigue, weight gain, dry skin and constipation — a reason to check your thyroid.
Bottom line
Many causes of constantly cold hands and feet are easy to check: some are found with blood tests (TSH, ferritin together with CRP, a complete blood count and, if you have numbness, B12), some on examination. Hypothyroidism and iron-deficiency anemia are treated. Primary Raynaud's affects about 5% of people, and 12.6% of them developed a secondary disease over about 4 years. You can sort out the causes and choose the right tests at a consultation.
This material is for information only and does not replace a consultation with a doctor. Tests and treatment are chosen by a doctor based on an examination.
