In systemic sclerosis, faecal calprotectin is associated with micronutrient deficiency. Individual and median faecal calprotectin levels in systemic sclerosis patients with different degrees of micronutrient deficiency. 1-way analysis of variance, P = 0.005. Please note the logarithmic scale on the y-axis. Patients were subject to analysis of the following micronutrient deficiencies by laboratory examination of serum or plasma: iron, vitamin B12, zinc and folic acid. Subjects with pathological testing according to local laboratory standards were regarded as micronutrient deficient. Patients with pathological testing for more than one of the aforementioned micronutrients were categorised as having multiple deficiencies.