This study evaluate the serum uric acid lowering effect of sodium bicarbonate as well as its safety in patients with asymptomatic hyperuricemia or gout. Half of the participants will receive sodium bicarbonate only, while the other half receive none.

Inclusion Criteria:

1. Sign informed consent form;
2. Serum uric acid ≥420mmol/L;
3. Within the age range of 18-65 years old;
4. Within the BMI range of 18-30kg/m2;
5. Both men and women are eligible

Exclusion Criteria:

1. General situations

   • Pregnancy or lactation；
   • Participants who can't take contraception during the study or within one month after the completion of the intervention;
   • Situations which will harm the participants;
   • Participants with bad compliance.

2. Taking part in another trail

3. Gout flares happening over the last one month;

4. Administration of medications over the last one month, including: allopurinol, Febuxostat,benzbromarone, and/or sodium bicarbonate；

5. urine pH>7.0;

6. Hepatic function：ALT and/or AST and/or TB>1.5 upper limit of normal (ULN);

7. Renal function：eGFR<60 ml/min for MDRD and/or urine protein>0.5g/24h；

8. Hypertension：>140/90mmHg;

9. Type 2 diabetes or taking drugs for lowering glucose (not including prediabetes);

10. Urinary stone,urinary infection;

11. Taking drugs ove the last one month and during the trial, including：thiazide diuretic, Loop diuretics, pyrazinamide,ethambutol, tacrolimus, niacin, aspirin, estrogen, losartan, amlodipine, reserpine, vitamin C，fenofibrate，atorvastatin， sulfonylureas，biguanides，NSAIDs;

12. Disease which influence serum uric acid, such as cancer, lymphoma, and etc.

13. Severe disorders involving heart, liver, kidneys, brain, lungs,digestive tract, rheumatoid disease, blood, endocrine, infection, and etc;

14. Blood donation or excessive loss of blood over the last 3 month.