Cold stimulus-fingertip lacticemy: standardization of the test in normal volunteers and diagnostic application for systemic sclerosis.
OBJECTIVE
To standardize the cold stimulus-fingertip lacticemy test (CS-FTL) in normal individuals and to establish reference levels for discrimination of normal individuals and patients with systemic sclerosis (SSc).


METHODS
FTL was determined before (pre-CS) and 3, 8, and 13 min after cold stimulus (post-CS) in 94 normal controls according to gender and age. Diagnostic performance of DeltaCS-FTL (percentage difference between post- and pre-CS-FTL) was tested comparing 25 SSc patients and the 94 normal individuals by ROC curve analysis.


RESULTS
Successive FTL determinations in the same fingertip yielded consistent results and the whole CS-FTL test proved to be reproducible. Pre-CS-FTL in SSc patients was higher than in normal controls (P<0.001). FTL decreased after cold stimulus (negative DeltaCS-FTL) in normal controls while SSc patients presented positive DeltaCS-FTL. Gender did not influence pre-CS-FTL and post-CS-FTL in normal controls. The decrease in FTL after cold stimulus was more prominent for normal individuals between 25 and 34 years old in comparison to other age subgroups, with statistical significance for females at 3 min post-CS (P<0.05). ROC curve analysis showed better diagnostic performance with post-CS-FTL at 8 and 13 min.


CONCLUSIONS
CS-FTL test provides a reproducible quantitative biochemical parameter that reflects fingertip microcirculation status and was able to discriminate patients with SSc and normal controls, with optimal performance with post-CS-FTL at 8 to 13 min.
Kayser
Cristiane
C
Rheumatology Division, Escola Paulista de Medicina, Universidade Federal de São Paulo (UNIFESP), Rua Botucatu 740, 3 andar, São Paulo, SP 04023-062, Brazil.
Pucinelli
Mário L C
ML
Fontenelle
Sheila M A
SM
Andrade
Luís E C
LE
D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D003080:Cold Temperature; D005260:Female; D005385:Fingers / Q000098:blood supply* / Q000502:physiology*; D006801:Humans; D019344:Lactic Acid / Q000378:metabolism*; D008297:Male; D008833:Microcirculation; D012372:ROC Curve; D011934:Reagent Strips / Q000378:metabolism; D012015:Reference Standards; D015203:Reproducibility of Results; D012595:Scleroderma, Systemic / Q000175:diagnosis*; D012680:Sensitivity and Specificity; D013053:Spectrophotometry; D013997:Time Factors
D011934:Reagent Strips; D019344:Lactic Acid