Cold intolerance

Cold intolerance — feeling persistently cold when others around you are comfortable, needing extra layers, having cold hands and feet even indoors — is a symptom of dysregulated thermoregulation. The body produces heat primarily through metabolic activity (driven by thyroid hormone) and through circulation (driven by heart and vasomotor tone). Anything that slows metabolism or reduces oxygen-delivery capacity will leave the patient feeling cold. The clinically important short-list: hypothyroidism (the textbook cause — pair it with fatigue, weight gain, constipation, dry skin and hair thinning), iron-deficiency anaemia (low oxygen-carrying capacity), B12 deficiency, malnutrition / very low BMI, peripheral artery disease (cold feet only). Less commonly, Raynaud's phenomenon (cold + colour-change in fingers triggered by cold or stress), hypothalamic dysfunction, autonomic failure, or sustained use of beta-blockers.

• Hypothyroidism — TSH up, free T4 down; classic with fatigue, weight gain, constipation, hair loss, dry skin.
• Iron-deficiency anaemia — low haemoglobin and ferritin; often with fatigue and pallor.
• B12 / folate deficiency — anaemia + neurological symptoms.
• Low BMI / under-nutrition — insufficient metabolic substrate.
• Peripheral artery disease — cold + pale feet, claudication.
• Raynaud's phenomenon — episodic white-blue-red colour change in fingers/toes.
• Beta-blockers — vasoconstriction at the periphery.
• Anorexia nervosa, hypothalamic injury — neuroendocrine causes.

First-line panel: TSH (always), CBC + ferritin + iron studies, vitamin B12, basic metabolic + glucose. Add 25-OH vitamin D if other deficiencies present (often clustered). Mediora.AI interprets this panel together — the (high TSH + low haemoglobin + low ferritin) cluster is sensitive for the commonest causes.