High doses of fluoride do not affect cyclic AMP levels in human and rat plasma or urine

Study on blood biochemical diagnostic indices for hepatic function biomarkers in endemic skeletal fluorosis

The aim of the study was to determine the relationship of fluoride in drinking water to liver function in individuals living in normal and seven endemic fluorosis areas of Punjab, India. The concentration of fluoride in drinking water of different areas varied from 5.9 to 24.5 mg/L. Study group consisted of 705 patients in the age group between 20 and 60 years (mean age of 39.35±11.27) affected with osteodental fluorosis were compared with 300 age- and sex-matched controls (with mean age of 35.28±8.25 years). Biochemical data was analyzed by one-way analysis of variance (ANOVA) with post hoc Tukey-Kramer and Bonferroni multiple comparison tests. The relationship between hepatic enzymes was calculated by Pearson's correlation and linear regression. The results revealed significantly (P<0.001) higher concentration of serum fluoride in patients when compared to control. The mean activities of cyclic adenosine monophosphate (AMP), alkaline phosphatase (ALKP), acid phosphatase (ACP), aspartate aminotransaminase (AST), and alanine aminotransaminase (ALT) were significantly (P<0.05-0.001) elevated in patients from all fluoride areas. ANOVA with post hoc Turkey-Kramer and Bonferroni multiple comparison test demonstrated a significant (P<0.0001) variance in the activities of cAMP, ALKP, ACP, AST, and ALT in fluorotic patients, with elevation in water fluoride levels. Maximum elevation of 196.14% (ACP), 99.31% (cyclic adenosine monophosphate; cAMP), 72.08% (ALT), 60.14% (AST), and least 21.35% (ALKP) was recorded in patients exposed to 24.5 mg/L fluoride in drinking water. There was positive correlation between water fluoride, serum fluoride and AST (r=0.77, 0.91), ALT (r=0.82, 0.90), ALKP (r=0.88, 0.97), and ACP (r=0.74, 0.85). Pearson's correlation demonstrated highly significant (P<0.05) positive relationship between water fluoride and cAMP (regression equation: Y=0.9807×+22:081, =0.84; r=0.92, P<0.05). The increased levels of transaminases in fluorotic patients suggest alteration in liver functions. The level of alkaline and acid phosphatase was increased during fluoride intoxication which is also an early marker of hepatic cell damage because of its specificity and catalytic activity. The elevated levels of enzymes are reflective of bone disorders, which are characterized by increased osteoblastic activity. There levels increased several times if cellular damage occurs in the liver. The results suggest that fluoride exposure intensifies the activities of hepatic function enzymes in osteofluorosis.