Chronic kidney disease (CKD) is a global public health problem. The prevalence of CKD in adults in China was 10.8%. Albuminuria measurement and estimating glomerular filtration rate (GFR) are the primary means of screening for CKD in epidemiological investigations. However, there are many important problems to be solved, whether albuminuria test or GFR evaluation. The investigators aim to detect thrice albumin-creatinine ratio (ACR) within three months, with simultaneous test of urinary protein-creatinine ratio (PCR), 24-hour urine protein excretion rate (PER) and 24-hour albumin albumin excretion rate (AER) to compare the effects of different times of screening for CKD and observe the daily physiological variation of ACR, PCR, AER and PER, derive ACR and PCR reference value on the basis of different genders, in order to facilitate the early diagnosis of CKD. Meanwhile, for more accurate assessment of GFR in Chinese populations, the investigators intend to validate beta-trace protein (BTP) based equation to evaluate GFR compared with 99mTc-diethylenetriamine pentaacetic acid (DTPA) renal clearance method. Then to develop GFR estimation equation based on the combination of serum creatinine, cystatin C, β2 -microglobulin and BTP applicable in China.

Chronic kidney disease (CKD) is a global public health problem. The prevalence of CKD in adults in China was 10.8%. Awareness of CKD is only 10.04% from a national cross-sectional survey in China. CKD is characterised by decreased estimated glomerular filtration rate (eGFR) and increased albuminuria, present for more than three months, and is associated with adverse outcomes (all-cause mortality, acute kidney injury, and end-stage renal disease), independent of hypertension and diabetes, age, or sex. CKD may carry a coronary heart disease risk similar to that of diabetes. The estimated lifetime risk of CKD stage 3a was more than 50%, lower than that of hypertension (83%-90% for a 55-year-old), but higher than those for diabetes (33%-39%), coronary heart disease (32%-49% for a 40-year-old), and invasive cancer (38%-45%).

Albuminuria measurement and estimating glomerular filtration rate (GFR) are the primary means of screening for CKD in epidemiological investigations. However, there are many important problems to be solved, whether albuminuria test or GFR evaluation. The investigators aim to detect thrice albumin-creatinine ratio (ACR) within three months, with simultaneous test of urinary protein-creatinine ratio (PCR), 24-hour urine protein excretion rate (PER) and 24-hour albumin excretion rate (AER) to compare the effects of different times of screening for CKD and observe the daily physiological variation of ACR, PCR, AER and PER, and repeat test to reduce the physiological variation, and further derive ACR and PCR reference value on the basis of different genders, in order to facilitate the early diagnosis of CKD. Meanwhile, for more accurate assessment of GFR in Chinese populations, the investigators intend to validate beta-trace protein (BTP) based equation to evaluate GFR compared with 99mTc-diethylenetriamine pentaacetic acid (DTPA) renal clearance method. Then the investigators aim to develop GFR estimation equation based on the combination of serum creatinine, cystatin C, β2-microglobulin and BTP applicable in China, for early and accurate assessment of GFR in Chinese people, and develop appropriate software to estimating GFR.

Inclusion Criteria:

• Health examination population at the department of nephrology
• Chronic kidney disease

Exclusion Criteria:

• Severe heart failure
• Acute renal failure
• Pleural or abdominal effusion
• Serious edema or malnutrition
• Skeletal muscle atrophy
• Amputation
• Ketoacidosis
• Patients who were taking trimethoprim or cimetidine or angiotensin converting enzyme inhibitors (ACEI) or angiotensin receptor blocker (ARB)
• Patients who had recently received glucocorticoid and hemodialysis therapy
• Female during the menstrual period
• Pregnant woman
• Who unable to sign informed consent

Chinese participants with CKD were selected from Nanjing First Hospital in China. All patients met the diagnostic criteria of CKD according to National Kidney Foundation-Kidney Disease Outcomes Quality Initiative (K/DOQI) clinical practice guidelines.