To explore the potential roles of serum Dickkopf-1 (DKK-1) and tartrate-resistant acid phosphatase 5b (TRAP5b) in gouty arthritis.
Blood serum DKK-1 and TRAP5b were assessed by ELISA method. The serum samples were collected from 150 patients with gouty arthritis, 100 with hyperuricemia and 100 healthy controls. Of the 150 gouty arthritis patients, 40 were diagnosed as acute gout (joint rash and pain), and the other 110 as chronic gout. At the time of serum sampling, various clinical and laboratory parameters were assessed. The correlations of DKK-1 or TRAP5b and clinical/laboratory parameters were analyzed.
(1) The serum levels of DKK-1 were elevated in the patients with gouty arthritis [(2 574.8± 997.9) ng/L] and with hyperuricemia [(2 009.4±756.9) ng/L] compared with the healthy controls [(981.8±770.7) ng/L],F=49.59, P<0.001. (2) The serum  levels of TRAP5b in the three groups were (3.2±1.4)U/L, (2.5±1.4)U/L and (0.2±0.2)U/L, respectively. F=103.039, P<0.001. (3) A significant difference of DKK-1 was observed between the patients with gouty arthritis and with hyperuricemia (t=3.998, P<0.001). Similarly, a significant difference of TRAP5b was  observed between the patients with gouty arthritis and with hyperuricemia(t=3.391, P=0.004). (4) In the patients with gouty arthritis, there was a positive correlation between DKK-1 and TRAP5b(r=0.47, P<0.001), while the levels of DKK-1 were not related with age, disease duration, body mass index or serum uric acid(r=-0.153, -0.123, 0.158, 0.00,P=0.126, 0.509, 0.381, 0.926). (5) In the patients with gouty arthritis, the serum levels of TRAP5b were elevated in the patients with tophi compared with the patients without tophi[(8.4±6.4)U/L vs. (4.0±1.6)U/L,t=-2.938,P=0.007]. The level of TRAP5b was associated with the disease duration(r=0.455,P=0.01), while there was no correlation between TRAP5b and age, body mass index or serum uric acid (r=0.135, 0.278, 0.144,P=0.595, 0.117,0.132).
In the patients with gouty arthritis, the levels of DKK-1 were remarkably elevated, and there was a positive correlation between DKK-1 and TRAP5b. Our results demonstrate that DKK-1 is involved in bone destruction in gouty arthritis.