Kidney failure

Kidney failure occurs when the kidneys lose the ability to filter waste products from your blood. There is a reduction in the GRF (glomerular filtration rate) and consequently the kidneys stop working properly and they cannot remove toxins from the bloodstream.

Kidney failure is the common end consequence of a wide variety of conditions affecting the kidneys.

Kidney failure may be classified into two different types:

• Acute kidney failure (develop suddenly and is often reversible).
• Chronic kidney failure (progress slowly, persist for three months or more and it is generally not reversible).

Kidney failure may have multiple causes that will be listed below according to the different types.

Acute kidney failure is an abrupt and fast decline it the kidney function within a few hours or days.

There are multiple causes:

• Prerenal causes (55%): Due to a sudden decrease in renal blood flow or increased renal vascular resistance.
  • Bleeding, dehydration, diuretics, severe burns, heart failure, cardiac tamponade, drugs, etc.
  • Sepsis, antihypertensive, anaphylaxis, hepatorenal syndrome.
• Intrinsic causes: (45%): Due to a due to a kidney problem (damage to the renal parenchyma).
  • Vascular problems in the kidneys (embolism, thrombosis, aneurysm, vasculitis, etc.)
  • Glomerular diseases (glomerulonephritis and vasculitis)
  • Acute tubular necrosis (caused by ischemia, external or internal toxics)
  • Interstitial nephritis (as a result of drugs, kidney infections, diseases by renal infiltration, etc.)
  • Renal transplant rejection
• Post-renal or obstructive causes (5%):
  • Ureters: Kidney stones, clots, neoplasms, etc.
  • Bladder: Neurogenic bladder, anticholinergic drugs, prostate disease, etc.
  • Urethra: Urethral stenosis, phimosis resulting in difficult urination, etc.

Chronic kidney failure is a progressive, and generally not reversible, loss of kidney function over the course of months or several years.

Multiple risk factors may contribute to chronic kidney disease:

• High blood pressure, diabetes, and cardiovascular diseases
• Family history of chronic kidney disease
• Obesity, cholesterol, and smoking
• Autoimmune diseases
• Lithiasis (stones in the kidney or urinary tract)
• Litiasis
• Lower urinary tract obstruction (LUTO)
• Kidney transplant
• Tumors
• Exposure to certain nephrotoxic drugs
• Advanced age (> 60 years)
• To belong to ethnic minorities
• Low-income and low-education

Chronic kidney failure may be the result of several conditions or causes that can be grouped into 6 large groups:

1. Diabetic nephropathy (most common)
   • Type 1 and 2 diabetes
2. Glomerulonephritis
   • Proliferative (lupus, vasculitis, hepatitis B and C, HIV, etc.)
   • Non-inflammatory (amyloidosis, Hodgkin's disease, tumors, etc.)
   • Hereditary (Alport syndrome)
3. Vasculitis
   • Renal artery stenosis
   • High blood pressure (arterial hypertension)
   • Sickle cell disease
   • Hemolytic-uremic syndrome
4. Tubulointerstitial diseases
   • Tubulointerstitial nephritis (by infection, lithiasis, NSAIDs, etc.)
   • Non-inflammatory (multiple myeloma, tumors, vesicoureteral reflux, prostate problems, etc.)
5. Cystic diseases of the kidney
   • Polycystic kidney disease
6. Kidney transplant
   • Cyclosporine or tacrolimus nephrotoxicity
   • Glomerular diseases

The symptoms can differ depending on the type and severity of the disease.

Acute kidney failure often has more symptoms, while chronic kidney failure tends to be silent. Chronic kidney failure may asymptomatic until the end stage of kidney disease.

The most common symptoms, according to the type of kidney failure are:

Acute kidney failure

• Prerenal acute kidney failure
  • Decrease in the amount of urine excreted (oliguria)
• Intrinsic acute kidney failure
  • Slight decrease in urine excretion (oliguria)
  • Edema, high blood pressure, with loss of proteins and blood through the urine
  • Skin disorders
• Postrenal acute kidney failure (due to urinary tract obstruction between the bladder and the urethra)
  • Anuria (inability to urinate)

Chronic kidney failure

• Electrolyte imbalance: High levels of calcium and phosphorus in the blood, blood acidity, increased potassium, etc.
• Cardiovascular disorders: High blood pressure, elevated renin, accumulation of fluid, heart failure, etc.
• Gastrointestinal: Nausea, vomiting, weight loss, etc.
• Hematological: Anemia with erythropoietin deficiency
• Neurological: Sensory polyneuropathy, restless leg syndrome, mental confusion
• Musculoskeletal: Bone pain
• Dermatological: Itchy skin
• Hormonal disorders: Erectile dysfunction, menstrual disorders, etc.

In order to better diagnose the type of kidney failure, it is necessary to study the medical history, anamnesis, physical exam, and additional tests.

• Lab tests:
  • Serum creatinine and GRF (Glomerular Filtration Rate) test that is the most important test to determine your stage of kidney disease
  • Biochemistry, blood count and coagulation tests
  • Determination of the albumin-to-creatinine ratio in urine
  • 24-hour urine collection
  • Urea clearance
  • Detect the level of protein and albumin in urine
  • BUN (Blood Urea Nitrogen)
• Imaging tests
  • Renal Doppler ultrasound (most important test, used to evaluate the kidneys, urinary tract, and renal vessels)
  • Abdominal X-ray
  • Computed tomography (CT)
  • Angiography or renal venography
  • Magnetic Resonance Angiography
• Kidney biopsy (when the cause is unknown).

Additionally, the severity of the kidney failure can be evaluated by the measure of GFR (Glomerular Filtration Rate):

• Stage 1 and 2 (mild): Glomerular Filtration Rate GFR > 60
• Stage 3 (moderate): Glomerular Filtration Rate GFR between 30 - 59
• Stage 4 and 5 (severe): Glomerular Filtration Rate GFR < 30

Treatment will depend on the cause of the kidney failure.

• Acute kidney failure (usually requires hospital treatment)
  • Treatment of fluid loss (diarrhea, vomiting, etc.) or decrease in the blood pressure (due to bleeding, antihypertensive drugs, etc.)
  • Avoid nephrotoxic drugs
  • Treatment of urinary tract obstruction (urinary catheter, double J stent, etc.)
  • Specific treatments depending on the type of kidney failure
  • In severe cases, dialysis may be needed
• Chronic kidney failure (usually treated on an outpatient basis): Since it is generally irreversible, treatment focuses on preventive measures to avoid the progressive deterioration of kidney function and treating the consequences of kidney damage.

Primary prevention of kidney failure should be focused on:

• Maintaining an adequate blood pressure and hydration
• Performing kidney function test regularly: creatinine, glomerular filtration rate, etc.
• The control of cardiovascular risk factors: high blood pressure, diabetes, cholesterol, smoking, sedentary lifestyle, weight, etc.
• Prevention of hyperkalemia (high potassium in the blood): avoid NSAIDs drugs and potassium-sparing diuretics, keep a balanced diet and avoid potassium-enriched salts.

To treat possible complications caused by kidney failure, it is recommended:

• Cardiovascular complications: Treatment with furosemide, beta-blockers, ACE inhibitors, ARBs, Digitalis, dialysis, etc.
• Hematological: Supplements with iron or erythropoietin
• Neurological: B1+B6+B12 supplements, dialysis, etc.
• Acid-base: Sodium bicarbonate
• Ionic: Diet low in salt and potassium, adequate use of diuretics
• Uremia: dialysis, kidney transplant, etc.
• Control of protein, sodium and potassium intake in the diet
• Pneumococcal vaccination (stage 3)
• Hepatitis B vaccination (stages 4 and 5)
• Stages 4 and 5 will always require follow-up by a nephrologist
• Kidney transplant in patients who meet the criteria
• Hemodialysis or peritoneal dialysis in severe kidney failure