Introduction
Chronic kidney disease (CKD) denotes permanent kidney damage that occurs over a period of time. Chronic kidney disease is divided into five different stages. Stages one and two indicate mild kidney damage. Stage three represents a moderate loss of kidney damage. Stage four indicates severe kidney damage, and stage five is kidney failure or close to failure. Stage three is the middle stage, with moderate kidney damage.
What Is Stage 3 CKD?
Stage three kidney disease is the middle stage of chronic kidney disease. Moderate kidney damage affects kidney function, and the individual starts noticing symptoms. The damage caused cannot be reversed, but it is possible to slow down the progression of the disease. Stage 3 is further divided into two stages based on the estimated glomerular filtration rate (eGFR). Stage 3A has an eGFR of 45 to 59 milliliter per minute, and stage 3B has an eGFR of 30 to 44 milliliter per minute.
The estimated glomerular filtration rate is a test that determines the level of kidney function and the stage of kidney disease. It measures the ability of the glomeruli in the kidneys to filter toxins from the blood. A normal eGFR should be 60 milliliters per minute or more. An eGFR less than this indicates loss of kidney function.
What Are the Causes of Stage 3 CKD?
The causes of stage three kidney disease include:
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Type 1 diabetes mellitus.
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Type 2 diabetes mellitus.
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Hypertension.
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Primary glomerulonephritis.
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Hereditary or cystic diseases.
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Chronic tubulointerstitial nephritis.
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Secondary glomerulonephritis or vasculitis.
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Plasma cell dyscrasias.
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Sickle cell nephropathy.
How Does Stage 3 CKD Occur?
Chronic kidney disease can occur due to disease processes in prerenal, intrinsic renal, or postrenal categories.
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Prerenal Disease - Chronic prerenal disease is seen in patients with chronic heart failure or cirrhosis. This causes a decrease in renal perfusion, which increases the episodes of intrinsic injury resulting in progressive loss of kidney function.
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Intrinsic Renal Vascular Disease - Chronic renal vascular diseases like nephrosclerosis damage the blood vessels, glomeruli, and tubulointerstitium. Other vascular diseases like renal artery stenosis cause ischemic nephropathy, which is characterized by tubulointerstitial fibrosis and glomerulosclerosis.
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Intrinsic Glomerular Disease - Streptococcal infections, infective endocarditis, shunt nephritis, lupus nephritis, vasculitis, Goodpasture syndrome, IgA (immunoglobulin A) nephropathy, focal segmental glomerulosclerosis, diabetic nephropathy, and amyloidosis are associated with proteinuria.
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Interstitial Tubular and Interstitial Disease - Chronic tubulointerstitial disease is caused by polycystic kidney disease, nephrocalcinosis, sarcoidosis, Sjogren syndrome, and reflux nephropathy.
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Postrenal Disease (Obstructive Nephropathy) - Prostatic disease, nephrolithiasis, or abdominal or pelvic tumors with mass effect on the ureters are the common causes of chronic obstruction.
Chronic kidney disease destroys the architecture of the kidneys and also causes progressive kidney fibrosis. It affects all the compartments of the kidneys, including glomeruli, the tubules, the vessels, and the interstitium, and results in scarring and fibrosis. The sequence of events that cause chronic kidney disease includes:
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Infiltration of extrinsic inflammatory cells in the kidneys.
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Activation, proliferation, and loss of intrinsic cells of the kidneys through apoptosis, necrosis.
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Activation and proliferation of myofibroblasts and fibroblasts, which produce the extracellular matrix; and
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Deposition of the extracellular matrix, which replaces the normal architecture of the kidneys.
Mechanisms like systemic and intraglomerular hypertension, intrarenal precipitation of calcium phosphate, glomerular hypertrophy, and altered prostanoid metabolism accelerate the progression of chronic kidney diseases.
What Are the Signs and Symptoms Associated With Stage 3 CKD?
Early stages do not present any symptoms. An individual starts experiencing symptoms usually at this stage of kidney disease. The signs and symptoms associated with this stage are:
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Nausea.
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Vomiting.
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Loss of appetite.
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Fatigue and weakness.
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Oliguria.
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Changes in the color of urine.
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Decreased mental sharpness.
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Sleep disturbance.
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Muscle twitches and cramps.
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Persistent pruritis.
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Scratch marks from pruritis.
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Swelling of feet and ankles.
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Chest pain due to uremic pericarditis.
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Hypertension.
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Shortness of breath due to pulmonary edema that occurs due to fluid overload.
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Skin pigmentation.
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Pericardial friction rub occurs due to uremic pericarditis.
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Uremic frost occurs due to high levels of BUN (blood urea nitrogen), resulting in urea in sweat.
What Are the Complications Associated With Stage 3 CKD?
Stage three kidney disease causes complications like high blood pressure, fluid retention, or fluid in the lungs. It causes heart failure due to a sudden rise in potassium levels. It decreases the immune responses. It also affects the central nervous system. It progresses to cause permanent kidney damage.
How Is Stage 3 CKD Diagnosed?
The diagnosis is based on history, examination, and other tests. The pathological abnormalities in the kidneys can be diagnosed with imaging studies and renal biopsy, abnormalities in urinary albumin excretion rates, or abnormalities in urinary sediment. This includes the following:
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Assessment of Glomerular Filtration Rate - The estimated glomerular filtration rate is measured to confirm the stage of kidney disease. The eGFR is 45 to 59 milliliter per minute in stage 3A and the eGFR is 30 to 44 milliliter per minute in stage 3B.
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Urine tests - A urine test assesses protein, albumin, and creatinine.
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Imaging Studies - Ultrasound examination shows the presence of reduced cortical thickness, increased echogenicity, or scarring. A renal ultrasound doppler is performed if renal artery occlusion is suspected.
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Biopsy - A biopsy is performed to diagnose the etiology of the disease and the extent of fibrosis.
How Is Stage 3 CKD Managed?
Stage three disease does not require dialysis or renal transplant. Medications are given to manage the underlying conditions causing kidney disease. Medications are also given to reduce the decline in the glomerular filtration rate. Drugs like iron supplements, calcium or vitamin D supplements, and diuretics are given to treat the adverse effects of stage three diseases like anemia, bone fractures, and edema. Diet modifications like reducing salt intake and avoiding foods rich in potassium, and protein, are advised. Lifestyle modifications like exercise, stress management, and smoking cessation are also essential.
Conclusion
Stage three kidney disease is the middle stage in the stages of chronic kidney disease. It causes moderate damage, which cannot be completely cured. It can be diagnosed by imaging studies, assessment of GFR, urine tests and renal biopsy. The worsening of the disease can be prevented with medications, diet, and lifestyle modifications. Early diagnosis and proper treatment can prevent the progression of the disease.
