The human body has two kidneys located on either side of the spine, they are bean-shaped and measure up to 6 cm in diameter. Anatomically, they occupy a retroperitoneal position (behind the peritoneum) and they are overhung by the adrenal glands.

The kidneys are responsible for filtering the blood of its toxins and forming urine as a by-product which will be excreted out of the body through the urinary system.

Functions of the kidneys 

The functional unit of the kidneys is called nephrons. There are millions of nephron units within one kidney.

Here are some functions of the kidney:

• Salt-water balance in the body.
• The blood concentration of many ions such as sodium, potassium, nitrogen, calcium and many others…
• Blood pressure regulation is also one of the regulatory functions of the kidneys.
• Synthesis of a variety of hormones such as erythropoietin
• Metabolism of low molecular weight proteins like insulin

Kidney damage, resulting in what is called renal failure, depending on the conditions and the speed of treatment, can be reversible or irreversible called end-stage renal failure (ESRD).

Types of Kidney Failure

Primarily there are two main types of kidney failures - acute and chronic failures. Each is further divided into into subtypes.

Acute kidney failure:

Sudden and abrupt loss of renal function is called acute renal failure. This typically occurs within a matter of a few hours to a few days. The failure, in this case, can be reversed on remission of the cause of the diseased state. It can be due to the following reasons:

• Injury or trauma to the abdomen leading to severe laceration trauma to the kidneys
• Uncontrolled blood pressure
• Uncontrolled diabetes
• Contraction of arteries and veins due to any blood disease
• Kidney stones
• Blockade of ureters
• Ischemia
• Glomerulonephritis
• Renal artery rupture or blockade

According to the KDIGO criteria in 2012, AKI can be diagnosed with any one of the following: 

1. Creatinine increase of 0.3 mg/dL in 48 hours, 
2. Creatinine increase to 1.5 times baseline within last 7 days, or 
3. Urine volume less than 0.5 mL/kg per hour for 6 hours.

Acute kidney injury (AKI) has recently superseded ARF because it encompasses the complete clinical range, from a moderate rise in blood creatinine to overt renal failure.

Prerenal acute renal failure (ARF) 

Sudden insufficient renal blood supply can lead to high toxin build-up in the blood. Urine output is subsequently reduced to a great extent and the body may enter a state of shock, if not treated immediately. Heart failure (CHF) is one of the more prominent outcomes of this type.

Hypotension, volume contraction (e.g., sepsis, hemorrhage), severe organ failure (e.g., heart failure or liver failure), and medicines such as nonsteroidal anti-inflammatory drugs (NSAIDs), angiotensin receptor blockers (ARB), and angiotensin-converting enzyme inhibitors (ACEI), as well as cyclosporine.

Intrinsic acute renal failure

Loss of kidney function itself is referred to as intrinsic ERF. The primary cause of this type can be cancer, autoimmune diseases, kidney stones, trauma, injury, alcohol and toxin content, etc. The remission begins with the treatment of causative factors. However, acute tubular necrosis and acute interstitial nephritis are the two main causes of intrinsic ERF

Acute tubular necrosis (caused by prolonged prerenal failure, radiographic contrast material, drugs such as aminoglycosides, or nephrotoxic substances), acute interstitial nephritis (drug-induced), connective tissue disorders (vasculitis), arteriolar insults, fat emboli, intrarenal deposition (as seen in tumor-lysis syndrome, increased uric acid production, and multiple myeloma).

Postrenal acute renal failure

Kidneys are responsible for filtration of blood and its resulting urine formation. This urine must be excreted from the body in order for the process to reach its completion. Post renal complication is associated with the inability to remove urine from the body. Any point in the urinary tract beginning from the ureters up to the cervix can be linked to this type of renal failure.

Chronic kidney failure:

Loss of renal functions that occurs over a course of a few years is referred to as chronic renal failure. The reduced value of GFR i-e <60ml/min/1.73m2, frequently for up to 6 months is the defining criterion for the chronic disease. There is a wide range of reasons for it, such as:

• Prolonged hypertension
• Prolonged diabetes
• Diabetes nephritis
• Kidney stones
• High blood uric acid and gout

Prerenal chronic kidney failure

Optimum blood supply to the kidneys is crucial not only for the blood filtration process but also for the oxygenation of the nephrons. Insufficient blood supply to kidney nephrons results in decreased glomerular filtration rate (GFR). Kidneys with a chronic disease cannot cope with reduced GFR for a prolonged duration. Thus, the kidneys begin to shrink and reduce in size and volume. This process may prolong to a few years before it can cause renal failure.

Intrinsic chronic kidney failure

Kidneys are the filtration system of the body. In addition, the regulation of hormones, blood pressure, and salt ion balance are some of its crucial roles, too. If the kidneys begin to lose their functions over a period of time, then such failure is categorized as intrinsic damage.

Postrenal chronic kidney failure

Similarly, as in the case of acute failure; post-renal chronic failure is the stage when the urine excretion is haltered. Damage to the urinary tract at any point for a longer duration can lead to build-up of toxins in the nephrons. If not diagnosed and treated on time, this can progress to renal failure, too.

Epidemiology

AKI has been reported to occur in 1% of patients on hospital admission, 2% to 5% of patients throughout hospitalization, up to 37% of patients treated in intensive care units (ICUs), and 4% to 15% of patients after cardiovascular surgery.

• The overall incidence of AKI is predicted to be 209 individuals per million people per year, with 36% of AKI patients requiring renal replacement treatment.
• CRF incidence and prevalence in the United States are unknown. According to the Third National Health and Nutrition Examination Survey (NHANES III), about 2 million Americans had a blood creatinine level of 2 mg/dl or above.
• CRF has been shown to be more common in men than in women. This gender discrepancy extends to end-stage renal disease (ESRD).
• In the United States, nearly 100,000 people acquire ESRD each year.
• Both the incidence and prevalence of ESRD are three times higher in blacks than in whites.

Pathophysiology

Failure of the kidneys Pathophysiology can be defined as a series of processes that occur during an acute insult in the setting of acute renal failure, as well as progress over time in the case of chronic kidney illnesses. AKI is broadly categorized into three groups:

1. Prerenal azotemia (reduced renal blood flow): Prerenal AKI develops as a result of either an absolute decrease in extracellular fluid volume or a decrease in circulating volume despite a normal total fluid volume, as seen in advanced cirrhosis, heart failure, and sepsis. Normally, the kidney's auto-regulatory system maintains intra-capillary pressure during the early phase by generating afferent arteriole dilation and efferent arteriole constriction. When prerenal conditions worsen, renal adaptive mechanisms fail to adjust, disguising the decrease in GFR and increase in BUN and creatinine levels.
2. Intrinsic renal parenchymal illnesses (renal azotemia): Intrinsic disorders are those that affect the glomeruli, vasculature, or tubulointerstitium.
3. Obstruction of urine outflow (postrenal azotemia)

The pathophysiology of CRF is mostly associated with unique starting mechanisms. Adaptive physiology plays a role over time, resulting in compensatory hyperfiltration and hypertrophy of remaining viable nephrons. As the injury progresses, histopathologic alterations such as glomerular architectural distortion, aberrant podocyte activity, and filtration disruption lead to sclerosis.

Kidney failure symptoms

The history and physical examination findings associated with renal failure include:

• Anemia: reduced blood hemoglobin levels
• Hypertension, or high blood pressure
• Edema, or swelling in limbs and feet
• Itching and tingling sensation, particularly in feet and legs
• Dry patchy skin
• Decreased urinary output
• Insomnia i-e inability to sleep
• Nausea and vomiting
• Yellowish hue on the skin along with increased pigmentation
• Tachycardia and arrhythmia
• Shortness of breath

Kidney failure urine color

Dark-colored urine appears thicker in concentration. The color changes from light yellow to dark yellow to brown and even red during the end stages. The characteristic smell of urine also becomes more pungent and profound.

Kidney failure rash

A rash might appear when your kidneys are unable to eliminate waste from your body. One rash that arises in persons who have end-stage renal illness involves tiny, dome-shaped, and exceedingly irritating pimples. As these bumps disappear, new ones might appear. The little lumps might sometimes come together to produce rough, elevated areas.

Diagnosis of renal failure  

As mentioned in the history and physical exam chapters, patients with renal failure exhibit a range of clinical manifestations. Many individuals are asymptomatic and have an increased serum creatinine concentration, abnormal urine tests (such as proteinuria or microscopic hematuria), or abnormal radiologic imaging of the kidneys that is discovered by chance. The following are the essential laboratory and imaging investigations that should be ordered in patients with renal failure.

Laboratory Tests

• Urinalysis, dipstick, and microscopy   

1. Dipstick for blood and protein; microscopy for cells, casts, and crystals
2. Casts: Pigmented granular/muddy brown casts-ATN; WBC casts-acute interstitial nephritis; RBC casts-glomerulonephritis

• Urine electrolytes

Imaging

• Renal ultrasound (US)
• Doppler-flow kidney US depending upon the clinical scenario
• An abdominal x-ray (KUB): Rules out renal calculi

If initial tests do not show an etiology, more sophisticated imaging techniques might be considered:

• Radionucleotide renal scan, CT scan, and/or MRI
• Cystoscopy with retrograde pyelogram
• Kidney biopsy

Kidney failure stages

Kidney failure or end-stage renal disease is classified into five main stages:

• Stage I:

This is the initial and mild stage. There is no substantial damage to the kidney functions and up to 90% of function is still retained and saved. The GFR value is also nearly more than 90ml/min. since the damage has merely begun, it can be reversed. Doctors recommend a regimen of medications along with lifestyle modifications. Avoiding alcohol and drugs, fizzy drinks, salty food, high protein diet etc. should be eliminated to achieve progress.

• Stage II: 

This stage is a step further from stage I, but still salvageable. The GFR value lies between 60 to less than 90ml/min. The patient begins to experience symptoms of renal deficit more frequently. Proteinuria, i.e. protein in the urine as well as creatinine in urine is observed during urine C/E testing. Uncontrolled diabetes and hypertension are almost always present in such patients. Healthy lifestyle maintenance becomes crucial and decisive at this stage of chronic kidney disease (CKD).

• Stage III:

This mild to moderate damaged condition of Stage III is further categorized into stage 3A and stage 3B. This classification is done on the basis of eGFR values obtained in renal function testing (RFTs). The overall eGFR is reduced between 30 to 59ml/min. Even though the condition has reached a substantially damaged state, some patients may still remain asymptomatic. However, others may experience edema in their hands and feet, joint pain, pain while urinating, hypertension, etc.

• eGFR between 45-59 ml/min is observed in stage 3A
• eGFR between 30-44 ml/min is observed in stage 3B

although the kidney and nephron damage cannot be reversed at this stage, it is highly possible to stop the disease from progressing further. A healthy lifestyle and eating habits are key factors in controlling the disease.

• Stage IV: 

At this point, the disease has progressed to an advanced stage and only 25-30% of kidney function is left, the eGFR is reduced to 15 to 29ml/min. Technically speaking, stage 4 is not the kidney failure stage since some glomerular filtration is still present. However, if the disease is not handled at this point, then kidney failure is inevitable. 

Symptoms of stage 4 kidney disease

The following symptoms are more frequently seen at this stage:

• Edema (swelling in hands and feet)
• Severe back pain
• Kidney pain located at the back on the lateral sides of spine
• Dark-colored smelly urine
• Pain while urinating
• Loss of appetite
• High blood pressure
• Anemia

What is the diagnostic testing done at stage 4?

A nephrologist will conduct a renal function test (RFT's) in order to monitor the disease’s progression and spread. The testing process focuses on monitoring blood creatinine value, urea value, blood Hb, protein in urine, phosphorus, and calcium values.

Kidney failure treatment

Treatment options for renal failure vary greatly and are determined by the etiology of the failure. Options are broadly classified into two categories: treating the cause of acute renal failure vs replacing renal function in acute or chronic circumstances and chronic diseases. The therapy for renal failure is summarized here.

Acute Renal Failure

• The primary focus is on addressing the underlying cause and any accompanying consequences.
• In the case of oliguria and no volume excess, a fluid challenge with careful monitoring for volume overload may be helpful.
• In the event of hyperkalemia accompanied by ECG abnormalities, IV calcium, sodium bicarbonate, and glucose with insulin should be administered. These approaches force potassium into cells and can be complemented by polystyrene sulfonate, a potassium remover. Hemodialysis is also an emergency removal procedure.
• Fluid restriction for oliguric patients should be 400 mL Plus the previous day's urine output (unless there are signs of volume depletion or overload).
• If there is acidosis, intravenous or oral serum bicarbonate is given instead of emergency/urgent dialysis, depending on the clinical condition.
• If an obstructive etiology is present, treat as needed, and patients who have bladder outlet blockage due to prostatic hypertrophy may benefit from Flomax or other selective alpha-blockers.

Immediate Dialysis Indications  

• Severe hyperkalemia
• Acidosis
• Volume overload refractory to conservative therapy
• Uremic pericarditis
• Encephalopathy
• Alcohol and drug intoxications

Treatment for stage 4 chronic kidney disease

The treatment regimen at this point has two objectives:

1. Prevent the disease from further progressing
2. Blood filtration and purification to make up for the lost kidney functions

Since the glomerular filtration has reduced substantially at this stage, therefore, the immediate goal is to start the dialysis process as soon as possible. Following are the main treatment courses adopted:

• Dialysis for kidney failure: This could be either hemodialysis, the removal of toxins from blood via a vein from the arm, or it could be peritoneal dialysis which is a needle-free type. Both the methods focus on blood filtration and need to be done at least once a week or more depending on the condition of the patient.
• Transplant: The doctors at this stage prefer to add the patient to the transplant list or to look for donors in the immediate family. It is possible that during the dialysis, the condition of the kidneys may worsen. Therefore, having a pre-set plan in order can be life-saving.

• Stage V:

This is also called end-stage renal disease (ESRD). The kidney function at this point has severely been compromised and reduced. The eGFR is less than 15ml/min. Some of the frequently seen symptoms are:

• Nausea and vomiting
• Fever and lethargy
• Headaches
• Loss of appetite
• Loss of energy and will to perform normal daily functions
• Irregular B.P and Glucose
• Edema and swelling in limbs
• Back pain
• Kidney pain
• Bladder and lower abdominal pain
• Radiating pain in limbs
• Tingling and numbness sensation in toes
• Changes in skin color which usually involves more pigmentation and coloring in the skin

The treatment plan for stage 5 renal failure:

Since the kidney function at this point is close to none, it is, therefore, critical that the patient is immediately placed on dialysis. In addition, a transplant is a more permanent treatment. 

Diet for stage 5 renal failure:

• Avoid foods with high salt content
• Avoid foods with high potassium, phosphorus, and calcium content
• Consume low saturated fats
• A low protein diet should be taken
• Higher intake of vitamin B and vitamin C containing foods

Kidney failure diet

Instead of canned veggies, go for fresh or frozen vegetables. Before preparing or eating canned veggies, drain and rinse them to eliminate excess salt. Avoid processed meats like ham, bacon, sausage, and lunch meats. Instead of crackers or other salty snacks, eat fresh fruits and vegetables.

Complications with Kidney Diseases

The kidneys play both regulatory as well as purification and excretion roles in the body. Being a vital organ, the consequences of kidney failure can be dire. The following are the complications associated with renal failure:

• Pericardial effusion and pericarditis: End-stage renal disease leads to accumulation of metabolic by-products and toxins in the blood. This in turn leads to inflammation of the pericardium (the layer surrounding the heart). This condition is called uremic pericarditis. The inflammation causes constriction of heart vessels, angina, and myocardial infarction (MI). Immediate administration of dialysis together with anti-inflammatory drugs is essential for the treatment of the condition.
• Pulmonary edema: The metabolic toxin accumulation in the body also affects the visceral walls of the lung membranes. This causes fluid retention in the blood vessels in order to maintain the osmolarity within the vessels. This fluid retention can lead to pulmonary edema. Dialysis and anti-inflammatory drugs are the treatment course for this condition.
• Hyperkalemia: Metabolic toxin retention in the body results in high potassium levels called hyperkalemia. Potassium plays an important role in the muscular contraction and relaxation of heart muscles. Therefore, hyperkalemia further leads to arrhythmias and altered heart functions.
• Anemia: Lower hemoglobin than the normal range is termed anemia. Roughly speaking, low red blood cells is called anemia. Blood cells are formed by the bone marrow in the bones when they receive the signal from erythropoietin hormone. This hormone is manufactured by the kidneys when there is hypoxia or low blood oxygen value. In renal failure patients, the reduced erythropoietin hormone formation leads to anemia.
• Difficulty breathing: shortness of breath is also frequently observed in kidney failure patients. This can be linked to both anemia and pulmonary edema.
• Hyperphosphatemia and cardiac calcification: Higher phosphate levels than the normal range can be very serious and fatal. This condition, if unchecked, can cause calcification of cardiac blood vessels. Cardiac arrest and death are the possible results of this condition.
• Hyperphosphatemia and renal osteodystrophy: Higher phosphate levels have a dire effect on bone density. Kidneys manufacture a type of vitamin D called calcitriol. This is associated with increasing calcium density in the bones along with parathyroid hormone (PTH). When renal failure begins, the amount of calcitriol decreases substantially and therefore calcium retention and absorption in the bones are severely affected. Hence, bone weakening occurs. This condition does not show any signs or symptoms and is often referred to as the “silent crippler”. Renal Rickets is also one of the severe outcomes of renal failure in children.

Conclusion 

The word kidney failure refers to the kidneys' inability to execute excretory functions, which results in the retention of nitrogenous waste products in the blood. The two types of kidney failure are acute and chronic renal failure. The end-stage renal disease occurs when a patient requires renal replacement treatment (ESRD).

Kidney failure is often managed by an interprofessional team of healthcare experts devoted to preserving renal function. Kidney failure has a high morbidity and death rate, and it costs the healthcare system billions of dollars each year.

When monitoring patients with renal failure, the nurse should take note of their urine output, potassium levels, blood sugar, and creatinine levels. Blood pressure and blood sugar control are critical in the prevention of renal disease. The nurse should regularly monitor all diabetics' renal function and send them to a nephrologist if it is worsening.

The pharmacist should highlight the significance of drug adherence in the management of high blood pressure. These individuals should be closely monitored to ensure that their renal function does not deteriorate. Finally, the patient should be counseled on good food, exercise, quitting smoking, and refraining from alcohol. If kidney disease is not properly controlled, it might progress to full renal failure, necessitating dialysis.