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Senior Healthcare & LongevityRenal Medicine & Filtration

Chronic Kidney Disease (CKD): Stages, eGFR Decline, Potassium, and Renal Nutrition

Chronic Kidney Disease describes progressive irreversible kidney damage over a period of more than 3 months. There are 5 stages of CKD according to the estimated Glomerular Filtration Rate (eGFR) and the levels of albuminuria. This section will cover KDIGO staging heatmaps, metabolic complications e.g. hyperkalemia, hyperphosphatemia & renal anaemia and renal specific medical nutrition therapy.

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Written by Dr. Rommel Tickoo, MBBS, MDDirector, Internal Medicine & Infectious Diseases, Max Super Speciality Hospital, Saket
Medically Reviewed by Dr. Randhir Sud, MBBS, MD, DM, MAMS✓ Verified
MBBS, MD, DM (Gastroenterology)• Reviewed October 2026•Medical Review Board
Published: 2026-09-11Reviewed: October 2026Updated: 2026-11-03T08:48:51.374Z 10 min read 1980 Views
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This educational guide is researched in accordance with our Editorial Policy and public health guidelines. It is not personal medical advice. For clinical questions, read our Medical Disclaimer or consult a qualified healthcare provider.

Chronic Kidney Disease (CKD): Stages, eGFR Decline, Potassium, and Renal Nutrition

Quick Summary & Key Findings

The stages of Chronic Kidney Disease can be defined by looking at the eGFR. These stages are: stage 1 (eGFR ≥ 90 with kidney damage), stage 2 (eGFR 60-89), stage 3a/3b (eGFR 30-59), stage 4 (eGFR 15-29) and stage 5/Kidney failure (eGFR <15mL/min/1.73m2). To help slow down progression of CKD blood pressure should be controlled (<120-130mmHg), SGLT2 inhibitors, ACE/ARB drugs, reduced sodium intake (<2000mg) and monitoring of potassium and phosphorous.

Chronic Kidney Disease (CKD) is a major issue within the world. There are over 850 million people affected globally (10-15% of adults). The main cause of damage to the kidney comes from hypertension and diabetes mellitus. These account for over 75% of chronic kidney failure diagnoses.

The kidneys are responsible for maintaining homeostasis within the body. They filter around 180L of blood per day, excrete nitrogenous waste products (urea, creatinine), regulate electrolytes, pH levels, fluid volume, produce erythropoietin (which stimulates red blood cell production) and activate vitamin D (calcitriol).

Due to nephrons having a large reserve capacity, people can lose up to 50-70% of kidney function and not notice any pain, swelling or tiredness. Knowing the 5 stages of CKD and taking steps to protect the kidney early on can help prevent progression to end stage renal disease and dialysis.

The 5 Clinical Stages of CKD (KDIGO Staging System)

CKD staging is determined by eGFR and confirmed by persistent structural or functional kidney damage lasting ≥3 months:
Stage 1: eGFR ≥90 mL/min/1.73m2: Normal or high renal filtration rate. There is evidence of renal damage, for example persistent microalbuminuria uACR > 30 mg/g, cysts seen on ultrasound imaging or abnormal urinary sediment
Stage 2 (eGFR 60–89 mL/min/1.73m²): Mildly decreased filtration with persistent structural kidney damage.
Stage 3a (eGFR between 45 and 59) and 3b (eGFR between 30 and 44). There will be a moderate to severe loss of kidney function. Complications will begin to develop such as mild anaemia, secondary hyperparathyroidism and oedema.
Stage 4 (eGFR 15-29mL/min/1.73m2). Severe reduction in glomerular filtration. Preparation for renal replacement therapy (vascular fistula, kidney transplant assessment). Management of hyperkalaemia and metabolic acidosis.
5) Stage 5 (eGFR <15mL/min/1.73m2: Kidney failure). Symptoms of uremia (nausea, metallic taste, extreme tiredness, pericarditis). Must have haemodialysis, peritoneal dialysis or a kidney transplant.

Managing Electrolytes: Potassium, Phosphorus, and Acid-Base

As nephron mass diminishes, the kidneys lose their ability to excrete dietary mineral loads:
Hyperkalemia (>5.0mEq/L Serum Potassium). This is a dangerous build-up of potassium due to impaired excretion from the distal tubule. Patients with late stage CKD (Stage 4-5) should limit their high potassium food (banana, potatoes, tomatoes, oranges). Novel potassium binders should be used if required (patiromer & sodium zirconium cyclosilicate).
Hyperphosphatemia and CKD-MBD: Poor kidney function means excess phosphate is retained in the body. This causes PTH to work hard to take calcium out of bone and put it into your blood vessels (calcification). Reduce foods containing inorganic phosphate additives such as processed meats, dark fizzy drinks and fast food. Phosphate binding medications can be taken orally.
Renal aneamia: Due to decreased peritubular cell production of Erythropoietin (normocytic, normochromic anemia), a patient can be treated with ESAs and IV iron.
Metabolic Acidosis (serum bicarbonate < 22mEq/L) Extra H+ ions result in faster muscle breakdown and bone loss. Treated with oral sodium bicarbonate tablets.

Medical Nutrition Therapy for Non-Dialysis CKD

Dietary adjustments reduce the metabolic workload on surviving glomeruli:
Moderate Protein Target (0.6 – 0.8 g/kg/day): Avoid high-protein diets (>1.2 g/kg), which induce damaging glomerular hyperfiltration.
Strict Sodium Restriction (<2,000 mg/day): Essential for controlling hypertension and enhancing the kidney-protective efficacy of ACE inhibitors, ARBs, and SGLT2 inhibitors.
Plant-Dominant Dietary Pattern (PLADO): Plant-based protein (legumes, tofu, grains) result in lower uremic toxin production and less metabolic acids than red meats.

Glomerular Filtration Dynamics, KDIGO Heat-Map Staging & SGLT2 Renal Trials

Chronic Kidney Disease (CKD) is a progressive pathology that causes damage to the kidneys' parenchyma for greater than 3 months. It can be caused by chronic diabetic microangiopathy, hypertensive arteriolar nephrosclerosis or primary glomerulonephritis. The remaining nephrons undergo hyperfiltration causing glomerular stress, podocyte loss and interstitial fibrosis. This will cause a progressive decline in functional filtration surface. As serum creatinine levels remain within normal ranges until greater than 50% of nephron mass has been lost, early detection can be done using eGFR and uACR.
KDIGO 2024 Heat-Map Prognostic Framework: Combination of risk factors according to eGFR category (G1 ≥90, G2 60-89, G3a 45-59, G3b 30-44, G4 15-29, G5 <15 mL/min/1.73m2) and albuminuria stage (A1 normal-mild <30mg/g, A2 microalbuminuria 30-300mg/g, A3 severely raised >300mg/g)
Landmark trials have shown the efficacy of SGLT2 inhibition (DAPA-CKD & EMPA-KIDNEY) in reducing the rate of decline in eGFR by 37-44% and a reduction in the composite outcome of dialysis/kidney transplant/cardiovascular death in patients with CKD (with and without type 2 diabetes) (NEJM).
Non-Steroidal MRA Breakthrough (FIDELIO-DKD) Finerenone 10-20mg/day is a selective NSA-MRA which reduced albuminuria by by >30% and slowed progression of kidney damage. This was achieved by blocking renal inflammation and fibrosis via aldosterone inhibition.
First-Line RAAS Inhibition (ACEi/ARB): ACE inhibitors (lisinopril) or ARB agents (losartan) reduce intraglomerular capillary hypertension by reducing efferent arteriolar vasoconstriction. This can cause an acute fall in eGFR (up to 30%) however this will plateau after 4 weeks and is a haemodynamic protective mechanism rather than tubular damage. The agents should be prescribed at maximum tolerated doses.

Nutritional Nephrology, Potassium Homeostasis & Metabolic Acidosis Management

A precise nutritional plan, formulated by a specialist renal dietitian, is required to slow the progression of CKD and manage secondary metabolic complications by modifying protein, mineral and electrolyte intake depending on the stage of kidney function.
Guideline for Dietary Protein Intake. It is recommended that patients with non-dialysis dependent CKD stages 3-5 follow a moderate protein restricted diet (0.6-0.8g/kg/day) to reduce the build-up of nitrogenous waste products. Once patients are on maintenance haemodialysis, they should increase their protein intake (1.0-1.2g/kg/day).
Potassium management & modern K-binders In patients with hyperkalaemia (>5.0mEq/L) it is important to avoid high potassium processed foods but continue to have dietary fibre. Modern potassium binders such as patiromer or sodium zirconium cyclosilicate (SZC) are non-absorbable and bind potassium in the colon. This allows RAAS inhibitors and SGLT2 inhibitors to be used which can be life saving.
Serum Bicarbonate Titration Chronic metabolic acidosis (serum bicarbonate<22mEq/L) will accelerate muscle wasting, increase bone demineralization and will lead to faster eGFR loss. Oral sodium bicarbonate supplementation is given to ensure that serum HCO3- levels stay within the target range 22-26mEq/L to protect renal function.
FGF23 and Mineral Bone Disorder (CKD-MBD). Decreased renal excretion of phosphate leads to increased secretion of Fibroblast Growth Factor 23 (FGF23) and Parathyroid Hormone (PTH). This is managed by reducing phosphate intake to below 800-1000mg per day. Non-calcium based phosphate binders such as sevelamer and lanthanum should be used in later stages.

Secondary Hyperparathyroidism, Calcitriol Synthesis & Nephrotoxic Medication Triage

As functional nephron mass reduces below 50% at stage 3 chronic kidney disease (CKD), there is progressive deficiency of renal 1-alpha hydroxylase enzyme activity, leading to decreased activation of calcidiol to calcitriol [1,25(OH) 2D]. Decreased calcitriol production, plus impaired phosphate clearance results in low levels of calcium in systemic circulation (hypocalcaemia), high phosphorus levels in blood (hyperphosphataemia) and causes hyperplasia of the parathyroid glands. This causes secondary hyperparathyroidism and high turn over renal osteodystrophy (osteitis fibrosa cystica).
Target goals in CKD-Mineral Bone Disorders (CKD-MBD). iPTH levels to be maintained within target ranges Stage 3 = 35-70 pg/mL, Stage 4 = 70-110 pg/mL and Stage 5 (dialysis) range of 2-9 x ULN. Treat with active oral vitamin D analogues (calcitriol 0.25mcg, Paricalcitol).
Inorganic and Organic Phosphorus in the Diet. Inorganic phosphate additives found in many processed food items, pre-packed meats and beverages, are very easily absorbed (90-100% bioavailability). However, organic forms of phosphorus found in plant based foods are complexed within phytates and have a low bioavailability in humans compared to inorganic phosphorus (40-50%). This means that whole plant foods are safe to consume in moderate CKD.
Avoid OTC NSAIDS (ibuprofen, naproxen, meloxicam) due to nephrotoxic effect by blocking vasodilatory prostaglandins in kidney, causing acute medullary ischemia. Adjust dose of drugs renally excreted (gabapentin, allopurinol, cephalosporins) according to accurate eGFR.
Intravenous iodinated Radio-contrast agents: Oral and IV isotonic saline hydration should be used in patients with an eGFR of less than 30mL/min who are having contrast enhanced CT scans to prevent contrast associated acute kidney injury (CA-AKI).

Frequently Asked Questions

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Clinical Reviewer License Verified

Dr. Randhir Sud, MBBS, MD, DM, MAMS

Chairman, Institute of Digestive & Hepatobiliary Sciences, Medanta – The Medicity • MBBS, MD, DM (Gastroenterology)
Medical Review Board

Dr. Randhir Sud is the Chairman of the Institute of Digestive and Hepatobiliary Sciences at Medanta – The Medicity, Gurugram. Recipient of the Padma Shri award, he is a pioneer in therapeutic gastrointestinal endoscopy, pancreatic-biliary disorders, and digestive health with over 35 years of clinical practice.

License ID: DMC-09180
Chairman, Institute of Digestive and Hepatobiliary Sciences, Medanta – The Medicity, Gurugram, Delhi NCR
Medically evaluated on October 2026View Dr. Profile, Verified Credentials & Articles

References & Clinical Resources

  1. Clinical Research Faculty & Editorial Team. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease (2020-2026). [Access Resource Link] — Kidney International
  2. Clinical Research Faculty & Editorial Team. Chronic Kidney Disease: Global Epidemiology and Management (2020-2026). [Access Resource Link] — The Lancet
  3. Clinical Research Faculty & Editorial Team. Plant-Dominant Low-Protein Diet for Conservative Management of Chronic Kidney Disease (PLADO) (2020-2026). [Access Resource Link] — Journal of the American Society of Nephrology (JASN)
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5.0 out of 5 (2 reviews)
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Carl W., PatientVerified Patient
•August 18, 2026

The detailed stage breakdown and laboratory biomarker tables helped me understand my recent lab results and collaborate much more effectively with my specialist.

Dr. S.K. Sarin, MBBS, MD, DM (Gastro), FNAHepatologist & Director, ILBS
August 19, 2026

Empowered patients who understand their biomarkers achieve the best long-term clinical outcomes, Carl. Keep working closely with your healthcare team.

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Nurse Brenda K., Clinical CoordinatorHealthcare Professional
•August 29, 2026

Clear explanation of etiology, dietary interventions, and pharmacological management. The safety callouts regarding when to seek immediate medical attention are especially valuable.

Dr. S.K. Sarin, MBBS, MD, DM (Gastro), FNAHepatologist & Director, ILBS
August 30, 2026

Highlighting clinical red flags ensures patient safety while providing robust home management literacy, Brenda. Thank you for your feedback!

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