Median (IQR) concentration of NO‐derived species (nitrite, nitrate and RXNO) during cooling (A) and recovery (B). Measurements at four different time points during a standardized cooling and recovery experiment in healthy controls (n = 10 at all time points), primary Raynaud patients (n = 10 during cooling, n = 9 10 min after start recovery and n = 8 at the end of recovery) and systemic sclerosis patients (n = 10 during cooling and 10 min after start recovery, n = 9 at the end of recovery). During cooling: HC: nitrate: Δ = 0.28 [−0.53–4.04], nitrite: Δ = 0.01 [0.03–0.008], RXNO: Δ = 6.32 [3.65–4.56]; PRP: nitrate: Δ = −0.09 [−0.31–6.57], nitrite: Δ = 0.03 [0.0004–0.04], RXNO: Δ = 0.84 [1.16–4.09]; SSc: nitrate: Δ = 5.65 [6.03 to −9.17], nitrite: Δ = 0.03 [0.01–0.004], RXNO: Δ = 3.88 [3.72–3.24]. During recovery: HC: nitrate Δ = 6.34 [0.18 to −2.99], nitrite Δ = −0.05 [−0.03 to −0.04], RXNO Δ = −2.74 [−2.80 to −4.38]; PRP: nitrate Δ = 0.29 [1.07 to −5.89], nitrite Δ = −0.03 [0.001 to −0.03], RXNO Δ = 2.30 [4.22–5.61]; SSc nitrate Δ = −7.01 [−8.83 to −8.71], nitrite Δ = −0.007 [−0.02–0.02], RXNO Δ = −0.98 [−1.88 to −0.18].