Astragalus (Radix Astragali, huang qi) is one of the most popular herbs used in Traditional Chinese Medicine for treating kidney disease.
A number of studies have now confirmed that astragalus does indeed appear to offer renal protective benefits and can lower various markers of kidney damage such as serum creatinine, serum albumin and reducing proteinuria in diabetic kidney disease patients.
The major components of Astragalus membranaceus are polysaccharides, flavonoids, and saponins.
Pharmacological research indicates that the extract component of Astragalus membranaceus can increase telomerase activity, and has antioxidant, anti-inflammatory, immunoregulatory, anticancer, hypolipidemic, antihyperglycemic, hepatoprotective, expectorant, and diuretic effects. 
Astragalus is probably one of my favorite overall tonic herbs for supporting health and I feel it offers a good broad-spectrum of health benefits from it’s “adaptogenic” properties, to immune system support, to kidney/renal protective benefits, to anti-tumor/anti-cancer and also potentially promoting longevity/anti-aging by increasing telomerase activity.
Astragalus membranaceus (Huang Qi) as adjunctive therapy for diabetic kidney disease
An updated systematic review just recently published was conducted to evaluate the efficacy and safety of A. membranaceus preparations as an adjunctive therapy to conventional therapies for DKD.
Sixty-six studies, involving 4785 DKD participants, were included in the systematic review.
Meta-analysis showed that additional use of A. membranaceus injection reduced more albuminuria (32 RCTs, 2253 participants; SMD: 2.05 [-2.49, -1.61], I2 = 94%), proteinuria (26 RCTs, 1812 participants; SMD: 1.85 [-2.34, -1.37], I2 = 95%), and serum creatinine levels (32 RCTs, 2880 participants; -14.78 μmol/L [-19.22, -10.33], I2 = 97%) than conventional therapies alone did.
An anti-albuminuria effect was also observed in the oral A. membranaceus preparation group (four RCTs, 236 participants; SMD: 1.27 [-1.82, -0.73], I2 = 73%).
Meta-regression suggested that the treatment effect of A. membranaceus injection was associated with the baseline serum creatinine level. The adverse-events profile was similar between the additional A. membranaceus and control groups.
The updated systematic review and meta-analysis concluded:
The low quality of evidence suggested that adjunctive use of A. membranaceus preparations in addition to conventional therapies may be effective and tolerated for short-term reduction of albuminuria, proteinuria, and serum creatinine in DKD patients.
The findings should be considered with caution due to the lack of high-quality RCTs and significant heterogeneity and publication bias. Further RCTs are needed to confirm the long-term efficacy and safety of A. membranaceus preparations, especially of the oral form, in patient-important outcomes. 
Beneficial effect of Astragalus membranaceus on estimated glomerular filtration rate in patients with progressive chronic kidney disease
Another study published in 2012 found a beneficial effect of Astragalus membranaceus on estimated glomerular filtration rate in patients with progressive Stage 4 and 5 chronic kidney disease.
Glomerular filtration rate (GFR) is a test used to check how well the kidneys are working. Specifically, it estimates how much blood passes through the glomeruli each minute. Glomeruli are the tiny filters in the kidneys that filter waste from the blood. 
The study followed 35 patients with with CKD stages 4 and 5 whose estimated glomerular filtration rate (eGFR) decreased over a 3-month period before the start of A membranaceus treatment despite the use of conventional therapy.
The study concluded:
The results suggest that A membranaceus can maintain stable levels of eGFR and delay the initiation of renal replacement therapy in patients with progressive CKD stage 4. 
 Anti-Aging Implications of Astragalus Membranaceus (Huangqi): A Well-Known Chinese Tonic
 Astragalus membranaceus (Huang Qi) as adjunctive therapy for diabetic kidney disease: An updated systematic review and meta-analysis.
 Glomerular filtration rate – Medline Plus
 Beneficial effect of Astragalus membranaceus on estimated glomerular filtration rate in patients with progressive chronic kidney disease
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