The blood tests for cold intolerance are: TSH, Free T4, and Free T3 for thyroid; Ferritin and CBC for iron; and 25-OH Vitamin D. All three causes are common, all are treatable — and standard panels routinely miss the specific tests that confirm them.
Cold intolerance points toward three causes — thyroid, iron, and vitamin D — but the confirming tests are routinely left off a standard panel.
Cold intolerance points toward three causes, all common and treatable: an underactive thyroid, iron deficiency, and vitamin D deficiency. The thyroid sets how much heat your body produces; iron carries oxygen to the extremities; vitamin D is needed for muscle function and thermogenesis. All three are addressable — and all three are routinely missed by standard panels.
The confirming tests are the ones that get skipped. A standard thyroid check is often TSH alone, which misses a sluggish thyroid where free T4 and free T3 tell the fuller story. A CBC detects anaemia only once haemoglobin drops — ferritin, which shows iron depletion months earlier, is rarely included. And 25-OH Vitamin D is almost never ordered on a routine panel unless you specifically request it.
The three clusters below are what a cold-intolerance workup actually needs. Fatigue, dry skin, or hair thinning alongside the cold strengthens the case for thyroid and iron; muscle aches and low mood alongside it point toward vitamin D.
The three causes most associated with feeling cold all the time — checked properly, not just at the surface.
Doctors order what they're used to ordering. Being specific about what you want, and why, changes the conversation.
Getting the right tests ordered is step one. Reading the results properly is step two.
Upload your blood report and get a ranked read on every marker, adjusted for your context.
Analyze My Blood Test →