The switch is literal. Cold moves a receptor on the muscle around your small arteries to the surface, so the ordinary adrenaline in your blood, which does nothing at room temperature, slams the vessel shut 1. Blood leaves and the finger goes white, then blue as the last oxygen burns off; when the artery relaxes it floods back and burns red.
In 80 to 90% of people that's the whole story: an overtuned switch on normal vessels. This is primary Raynaud's, and it runs in families, starts young, and stays put for life 2. The rest have real damage underneath, so their Raynaud's is a symptom of something larger 3.
Which camp you're in is the whole question, because the answer sets the next decade of your care. Two cheap tests carry the weight. An ANA blood test is positive in under 5% of primary cases but over 90% of the connective tissue disease that drives the dangerous kind. A microscope look at the base of your fingernails is normal in primary and visibly distorted in secondary 4.
Some patterns raise suspicion on their own: one hand worse than the other, attacks that damage skin, tightening finger skin, onset after 40. Even a clean first screen isn't final; around 12 to 15% of people labelled primary later convert, so the follow-up exam counts as much 5.
Warmth and nicotine are yours to fix today; the screen is the one thing to ask a doctor for.
For most people with the primary version, nothing dramatic ever happens: winter is annoying, summer is fine, the attacks never escalate. The real cost is the low-grade dread of the next cold exposure, and getting attacks down lifts it. The minority with secondary disease face something else. About half of people with systemic sclerosis develop a slow-healing ulcer at a fingertip 3, and the same process that scars fingers also scars the lungs and their vessels. That's what the screen is really watching for. The antibody test isn't about the finger. It's about what the finger predicts.
The fine print โ when to skip it, and what people get wrong
This isn't "cold hands"; Raynaud's draws a sharp line, waxy white at one knuckle and pink past it. If you have to debate whether it counts, it probably doesn't. You also don't need all three colours to qualify 8.
Some common drugs make it worse and are worth reviewing at diagnosis: non-selective beta-blockers, migraine triptans and ergotamines, stimulants, and nicotine in any form. Heavy use of vibrating tools causes its own occupational form 2.
- 1Herrick AL (2012). The pathogenesis, diagnosis and treatment of Raynaud phenomenon. Nature Reviews Rheumatology. link
- 2Wigley FM, Flavahan NA (2016). Raynaud's Phenomenon. New England Journal of Medicine. link
- 3Hughes M, Herrick AL (2020). Raynaud phenomenon and digital ulcers in systemic sclerosis. Nature Reviews Rheumatology. link
- 4Cutolo et al. (2000). Nailfold videocapillaroscopy assessment of microvascular damage in systemic sclerosis. Journal of Rheumatology. link
- 5Pavlov-Dolijanovic et al. (2012). Late appearance and exacerbation of primary Raynaud's phenomenon attacks can predict future development of connective tissue disease. Rheumatology International. link
- 6Belch et al. (2017). ESVM guidelines โ the diagnosis and management of Raynaud's phenomenon. VASA. link
- 7Thompson AE, Pope JE (2005). Calcium channel blockers for primary Raynaud's phenomenon: a meta-analysis. Rheumatology (Oxford). link
- 8Maverakis et al. (2014). International consensus criteria for the diagnosis of Raynaud's phenomenon. Journal of Autoimmunity. link
Related in the handbook (5)
- โ Migraine drugs that block CGRP can make Raynaud's worse, since that signal helps open small vessels. Flag it to your neurologist.
- โ If your fingers go white in the cold, ice baths and cold plunges can trigger a full attack. This is one cold exposure to skip.
- โ Nicotine clamps down the same small vessels that misbehave in Raynaud's โ quitting is part of the standard treatment.
- โ Raynaud's is often the earliest visible clue to autoimmune disease, years before the rest shows up โ especially in women.
- โ Migraine and Raynaud's tend to travel together, both involving blood vessels that overreact.