Have you ever had your kidneys checked?
March 10 this year is the 17th World Kidney Day, the theme is "Everyone cares about kidney health - I love my kidneys, knowledge strengthens kidneys". Today, let's take a look at the common diseases related to kidney disease.
Chronic kidney disease (CKD) refers to a disease with abnormal kidney structure or function that affects health for more than 3 months, and is divided into two types: primary (glomerulonephritis nephropathy) and secondary (hypertensive nephropathy, diabetic nephropathy). Its low awareness, high prevalence, high medical costs, and poor prognosis are considered to be another disease that profoundly affects people's quality of life after diseases of the cardiovascular system, cancer and diabetes.
The burden of CKD disease is predominantly hypertensive nephropathy and type 2 diabetic nephropathy.
Among the various types of CKD, patients with hypertension and renal impairment are usually diagnosed with hypertensive nephropathy in the absence of evidence of primary kidney disease and diabetic nephropathy. Hypertensive nephropathy promotes the occurrence of cardiovascular adverse events, end-stage renal disease and sudden death, and seriously affects the quality of life of patients with CKD.
Diabetic nephropathy refers to CKD caused by diabetes, due to changes in people's eating habits, the prevalence of diabetes is increasing, and the incidence of diabetic nephropathy is also increasing. At the same time, among the different types of CKD, hypertensive nephropathy and type 2 diabetic nephropathy change most with age.
Therefore, in order to alleviate the burden of CKD, in addition to the need to increase the attention of the elderly to CKD, the prevention and treatment of chronic diseases such as hypertension and diabetes cannot be ignored.
1. Diabetes
1. Prevalence
About 537 million adults (aged 20-79) worldwide will have diabetes in 2021 (1 in 10 people); this number is expected to rise to 643 million by 2030 and 783 million by 2045. During this period, the world's population grew by an estimated 20 per cent, while the number of people with diabetes increased by an estimated 46 per cent. China has the largest number of diabetics, with more than 140 million patients in 2021, including 51.7% of undiagnosed patients [1]. More than 90% of people with diabetes in mainland China make up more than 90% of type 2 diabetes [2].
2. Diabetic nephropathy
Diabetic nephropathy (DKD) refers to chronic kidney disease caused by diabetes mellitus, and the lesions can affect the whole kidney (including glomeruli, tubular, renal interstitial, etc.). About 20% to 40% of diabetic patients in mainland China have diabetic nephropathy, which has become the main cause of CKD and end-stage renal disease. Risk factors for diabetic nephropathy include poor lifestyle habits, age, course, blood glucose, blood pressure, obesity (especially abdominal obesity), lipids, uric acid, and environmental pollutants. Decreased renal function is significantly associated with an increased risk of all-cause death in patients [2].
3. Laboratory testing of diabetic nephropathy
Diagnosis of diabetic nephropathy relies heavily on urinary albumin (or urine albumin/creatinine ratio (UACR)) and estimated glomerular filtration rate (eGFR) measurement, and comprehensive treatment based on hypoglycemic and antihypertensives, regular follow-up, and timely referral can improve outcomes in patients with diabetic nephropathy. UACR and serum creatinine are recommended for all patients with T2DM at least once a year (eGFR is calculated)[2].
4. Diabetic nephropathy pathology
Patients with DKD are routinely not biopsyed unless other causes of kidney disease are suspected or require special treatment, so pathological data are limited. Histologically confirmed that the prevalence of DKD was higher than previously recognized, and autopsies of 168 patients with DKD by Klessens et al. found that the proportion of clinically underdiagnosed DKD but histologically confirmed DKD was relatively high, suggesting that DKD could occur before clinical discovery[3].
Glomerular damage to DKD is characterized by mesangial hyperplasia, thickening of the glomerular basement membrane (GBM), and glomerular sclerosis. Diffuse mesangial hyperplasia generally occurs 5 years after the onset of DM, nodular lesions and diffuse lesions are the two stages of DKD, and GFR is inversely correlated with the degree of mesangial. GBM thickening is the earliest detectable pathological change in T1DKD and T2DKD, which can be observed within 1 to 2 years after the onset of DM, followed by significant albuminuria and increases with the prolongation of the course of the disease.
Tubular interstitial injury is a consistent feature of DKD, and although there is a correlation between interstitial changes and mesangial hyperplasia, interstitial fibrosis and tubular atrophy (IFTA) may not be associated with glomerular changes. Transparent degeneration of the arterioles in the ball and the ball is a typical pathological change of DKD. 95.4% of patients experience arterial hyaluronic degeneration in more than one site.
5. Non-diabetic nephropathy
Diabetes mellitus with renal impairment rather than typical DKD manifestations is called non-diabetic nephropathy (NDRD). T2DM pathologically confirmed by renal aspiration biopsy pathology at an incidence of 12% to 80% of diabetes mellitus, and the incidence of NDRD in patients with renal biopsy on T2DM in the study of Martin T[4] was 57.1%. Common pathological types of NDRD include: IgA nephropathy, membranous nephropathy, focal segmental glomerulosclerosis (FSGS), glomerular micropathy, and acute interstitial nephritis. Patients under 60 years of age are predominantly IgA nephropathy, and patients over 60 years of age are most commonly membranous nephropathy.
2. Hypertension
The 2012-2015 China Hypertension Survey (CHS) found that the normal high blood pressure of 18-year-old residents in mainland china ≥ was detected at a crude rate of 39.1%, and the weighted rate was 41.3%. It is estimated that there are 435 million people with normal high blood pressure in the country. The crude prevalence of hypertension in 18-year-old residents in China ≥ was 27.9% (weighted rate 23.2%). The prevalence of hypertension is 5.1% in young people (18 to 34 years old), compared with 59.8% in ≥ 75-year-olds. It is estimated that 245 million people in China ≥ 18-year-old adults have hypertension.
2. Hypertensive nephropathy
Hypertension is an independent risk factor for CKD. In mainland China, hypertension is the most common cause of end-stage nephropathy (17.0%), in addition to diabetic nephropathy and glomerulonephritis, and the prevalence of chronic kidney disease is as high as 7.5% in patients over 35 years of age, and the higher the prevalence of chronic kidney disease in patients over 35 years of age.
Clinically, hypertensive nephropathy is divided into benign hypertensive nephropathy and malignant hypertensive nephropathy according to the level of blood pressure and acute and slow condition.
3. Laboratory test for hypertensive nephropathy
If the basis of hypertensive nephropathy is found on routine examination, it is necessary to further improve the specialty examination of kidney disease such as urine microalbumin/creatinine, 24-hour urine microalbumin, 24-hour urine microalbumin, urine red blood cell ensemble, and renal dynamic imaging, and if necessary, renal aspiration biopsy.
4. Pathology of hypertensive nephropathy
Benign hypertensive nephropathy, mainly manifested as benign arteriolar nephrosclerosis, mainly arteriolar sclerosis and renal ischemic changes. Malignant hypertensive nephropathy is mainly manifested as malignant arteriolar nephrosclerosis, the size of the kidney is related to the course of hypertension, the kidney size is normal in the short course, and the kidney is reduced in the elderly [6].
3. Overweight/obesity
In 2016, the World Health Organization declared that the number of people who are overweight and obese globally reached 1.9 billion and 600 million, respectively. According to the Report on the Status of Nutrition and Chronic Diseases of Chinese Residents (2020), more than half of adults in mainland China are overweight/obese, and the rates of overweight/obesity among children aged 6 to 17, children under 6 years old and adolescents reach 19.0% and 10.4% respectively.
1. Obesity-related kidney disease in adults
Obesity affects human health, is a risk factor for diabetes, hypertension, cardiovascular disease, but also affects the kidneys. Kidney disease caused by obesity is called obesity-relatedglomerulopathy (ORG). The concept was first mentioned in 1974, and with the obesity epidemic, the incidence of ORG increased. Domestic studies have shown that the proportion of patients with renal biopsy confirmed ORG in the total number of renal biopsy patients gradually increased from 0.62% to 1.0%. ORG has a hidden onset, atypical clinical manifestations, and there is no standard treatment regimen. Obesity-associated nephropathy in adults accounts for 2 to 2.7 percent of renal biopsy samples [7].
2. Laboratory test for obesity-related nephropathy in adults
Among them, 55.9% of patients had small amounts of proteinuria, 40.1% of patients had moderate proteinuria, and 4.0% of patients had large amounts of proteinuria. Renal function is impaired in 9.7% of patients. Urinary RBP is abnormal in 55.9 percent of patients, and abnormal urinary RBP in 43.6 percent [8].
3. Obesity-related nephropathy pathology in adults
Simple obesity-associated glomerular hypertrophy (O-GM) or obesity-associated focal segment glomerulosclerosis with glomerular hypertrophy (O-FSGS); immunofluorescence manifests as oligoimmune complex deposition with nonspecific or segmental deposition of IgM and C3 [8].
Fourth, the elderly
The mainland is gradually entering an aging society, and age is an independent risk factor for the development of chronic kidney disease. The pathological spectrum of elderly patients with kidney disease is different from that of the general population, and there are more complications and higher case fatality rates. Renal function is affected by age, and while age increases, there is a physiological decrease in glomerular filtration function, and the risk of CKD increases by 1.22 times for each 10 years of age [10].
The seventh national census released in 2021 suggests that the aging process of the mainland population will further accelerate, with the population aged 60 and over accounting for more than 18%, and 1/3 of the total population of the mainland will be the elderly population in 2050. The burden of CKD disease in the elderly population is significantly higher than that of other groups, so the prevention and control of CKD in the elderly population cannot be ignored.
1. Kidney pathology in the elderly
In a study of kidney biopsy results in 966 patients with elderly nephropathy in Beijing[9], primary glomerular disease accounted for 79.1%, which remained the main pathological type; secondary glomerular disease accounted for 15,6% and tubular interstitial disease accounted for 5.3%. Among them, membranous nephropathy is the most common type of pathology, accounting for 47.3% of elderly patients with renal biopsy. This was followed by IgA nephropathy at 12.5% and minor glomerular lesions at 10.5%. Among secondary glomerular diseases, the most common is diabetic nephropathy, accounting for 6.9%.
A retrospective study analyzed pathological data from renal biopsy in elderly patients with nephropathy over the past 12 years [9]. In the three time periods from 2009 to 2012, 2013 to 2016 and 2017 to 2020, the proportion of membranous nephropathy did not change significantly, accounting for 44.4% to 51.2%, and the proportion of IgA nephropathy decreased significantly, from 15.4% (2009-2012) to 10.9% (2017-2020), but the difference in pathological composition was not significant. Among secondary glomerular diseases, the proportion of diabetic nephropathy has increased significantly in recent years, from 1.9% (2009-2012) to 10.0% (2017-2020).
5. Summary
The risk factors affecting the burden of CKD can be divided into metabolic factors, behavioral factors and environmental factors. Metabolic factors are mainly impaired renal function, hyperglycemia, hypertension, and high BMI index, behavioral factors are mainly high-sodium diet, and environmental factors are mainly low temperature and lead exposure. The mortality rate caused by CKD risk factors such as impaired kidney function, hyperglycemia, hypertension, and high BMI in China is lower than global, but the high-sodium diet and low temperature are slightly higher than global (see table below).
Table: Mortality from CKD risk factors in China and globally[10]
Among the different types of CKD, hypertensive nephropathy and type 2 diabetic nephropathy change most with age, so in order to alleviate the burden of CKD, in addition to the need to increase the attention of the elderly population to CKD, the prevention and treatment of chronic diseases such as hypertension and diabetes cannot be ignored.
CKD is a chronic noncommunicable disease with an emphasis on early prevention. A healthy lifestyle of reasonable diet, moderate exercise, smoking cessation and alcohol restriction, and psychological balance is especially suitable for the prevention and control of CKD. Regular screening of urine protein in patients with chronic diseases to identify early kidney damage is helpful for early screening, early diagnosis, and early intervention of CKD, reducing the disease burden of CKD injury. Guosai bio-urine protein testing facilitates early screening of CKD.
【Reference】
[1]. IDF Diabetes Atlas (10th edition)
[2]. Guidelines for the Prevention and Treatment of Type 2 Diabetes in China (2020 Edition)
[3].Wang Jie, Li Bing.Correlation between pathological changes in type 2 diabetic nephropathy and kidney prognosis.Chinese Journal of Integrated Traditional Chinese and Western Medicine Nephrology 2021,22(1).
[4].Ma Tingting.Clinical and pathological analysis of type 2 diabetic nephropathy.2020.
[5].China Cardiovascular Health and Disease Report 2020.
Duan Xiaorong, Yu Zhenqiu. Recommendations for the diagnosis and treatment of hypertensive nephropathy (Part 1).Chinese Rural Medicine,2021,28(1).
[7]. D’Agati VD ,Chagnac A , De Vries A PJ , et al. Obesity-related glomerulopathy:clinical and pathologic characteristics and pathogenesis. NatureReviews Nephrology, 2016.
Zong Huimin. Clinicopathology and prognosis analysis of obesity-associated kidney disease in adults.2019.
[9].Li Xia,Wu Yiru,Zhang Qidong,et al. Analysis of pathological types of renal biopsy in elderly patients with kidney disease. Chinese Journal of Clinicians,2021,49(11).
Ke Qian, Yu Chuanhua, Liu Xiaoxue, et al. Current status and trend analysis of chronic kidney disease burden in China based on GBD data. Public Health and Preventive Medicine, 2021, 32(5).
Editor: Ren Mileage Reviewer: Xiao Ran