Free serum and urine light chains in SSc patients and HC
The median value of serum and urine FLC in SSc patients and HC are shown
in Table 2. The median value of serum free k and free λ levels, k + λ
sum and k/λ ratio was significantly higher in SSc patients compared with
HC. SSc patients displayed significantly higher mean serum levels of
free k (23.5 mg/L vs 8.1 mg/L, p =0.0001) and free λ (17.5 mg/L vs
10.1 mg/L, p =0.0001) than HC. Free k serum levels were higher
than 19.4 mg/L in 57/72 (79.2%) SSc patients while none of the HC
displayed free k in serum higher than 19.4 mg/L (p =0.0001). Serum
free λ levels were higher than 26.3 mg/L in 7/72 (9.7%) SSc patients
while none of the HC showed serum free λ higher than 26.3 mg/L
(p =0.102). The median of k/λ sFLC ratio (1.4 vs 0.8) and the
median of k + λ sFLC (40.5 mg/L vs 19.6 mg/L) were significantly higher
in SSc patients if compared with HC (p =0.0001). The k/λ sFLC
ratio was higher than 1.65 in 22/72 (30.6%) SSc patients while none of
the HC presented k/λ sFLC ratio higher than 1.65 (p =0.0001).
In addition, SSc patients had statistically significant higher levels in
urine of free k-uFLC (13.5 mg/L vs 6.1 mg/L, p =0.0001) than HC.
There was no difference in the mean value of λ-uFLC between SSc patients
and HC (2.1 mg/L vs 2.4 mg/L, p =0.453]. Urine free k levels
were higher than 15.1 mg/L in 32/72 (44.4%) SSc patients while none of
the HC presented higher levels of free k (p=0.0001); only 1/72 SSc
patient (1.4%) had urine free λ levels higher than 10.1 mg/L and none
of the HC presented higher levels of λ (p =0.706). In SSc
patients, the mean level of the k/λ ratio in urine was higher than in HC
(6.7 vs 2.1, p =0.00019. The urine k/λ ratio was higher than 1.80
in 63/72 (87.5%) SSc patients and in 19 (63.3%) HC (p =0.007).
The mean value of the urine k + λ sum (16.5 mg/L vs 8.1 mg/L,p =0.001) was significantly higher if compared with HC.