Diseases of the Renal System

Kidney Disease

One of the most common diseases of the renal system is Kidney or renal disease, also known as nephropathy, it is thought to affect as many as 1 in 10 people in the UK population by some degree. Kidney disease is damage to the kidney(s) which can be either:

  • Chronic (damage that has occurred gradually over a period of more than 3 weeks) OR
  • Acute (damage which has occurred suddenly). Acute Kidney Disease (AKD) is also called Acute Kidney Injury.

Kidney disease can also be inflammatory or non-inflammatory. Inflammatory kidney disease is called nephritis and non-inflammatory kidney disease is called nephrosis.

Kidney disease usually causes a loss of kidney function to some degree and can result in kidney failure, the complete loss of kidney function. Kidney failure is known as the end-stage of kidney disease, where dialysis or a kidney transplant is the only treatment option.

The cause of chronic kidney disease is not always known but the most common risk factors are:

  • Diabetes – type 1 or type 2 diabetes
  • Hypertension – high blood pressure
  • Glomerulonephritis – Inflammation in the glomerulus (the cluster of capillaries at the end of each nephron)
  • Polycystic kidney disease
  • Autoimmune diseases
  • Vesicoureteral reflux – A condition where urine flows back up to the kidneys
  • Pyelonephritis – Prolonged inflammation caused by kidney infection
  • Interstitial nephritis – Inflammation of the kidney tubules
  • Kidney stones – obstruction in kidney or cancer can lead to kidney failure over a period of time
  • Overuse of certain medications
  • Drug (heroin or cocaine) abuse

In the early stages of CKD there may be no symptoms but as the disease progresses, symptoms might include:

  • Nausea
  • Loss of appetite
  • Fatigue
  • Oedema – swelling of the feet and ankles
  • Need to urinate more often, especially at night
  • Hypertension
  • Decreased mental sharpness
  • Problems with sleep
  • Blood in urine
  • Protein in urine
  • Twitching in the muscles and cramps
  • Persistent itching
  • Chest pain if fluid builds up around the lining of the heart
  • Shortness of breath is seen if fluid builds up in the lungs



Hydronephrosis, also known as obstructive uropathy, is a condition where one or both kidneys become stretched and swollen because of build-up of urine inside them. Hydronephrosis occurs when there is either a blockage of the outflow of urine, or reverse flow of urine already in the bladder (called reflux) that can cause the renal pelvis to become enlarged.

Hydronephrosis may or may not cause symptoms but usually the severity of symptoms depends on the cause and severity of urinary blockage. The main symptom is pain, either in the side and back (known as flank pain), abdomen or groin. Other symptoms can include:

  • Pain during urination,
  • Other problems with urination (increased urge or frequency, incomplete urination, incontinence)
  • Nausea
  • Fever

Hydronephrosis is usually caused by another underlying illness or risk factor resulting in a blockage. Causes of hydronephrosis include, but are not limited to:


  • Kidney Stones
  • Blood clot
  • Stricture (anastomotic or traumatic)
  • Congenital blockage (a defect that is present at birth)
  • Tumour or cancer (examples include bladder, cervical, colon, or prostate)
  • Enlarged prostate (noncancerous)
  • Pregnancy
  • Urinary tract infection (or other diseases that cause inflammation of the urinary tract)
diseases of the renal system paper

Kidney Stones

Kidney stones, also known as nephrolithiasis or renal calculus, are extremely common, it is thought that there are more than 1 million cases of kidney stones per annum in the UK. They most often affect people aged 30 to 60 & are more prevalent in men than women.

Kidney stones are caused by waste products such as calcium, ammonia, or uric acid in the blood, which occasionally build up to form crystals that collect inside the renal system.

They vary greatly in size; some are as small as a grain of sand whereas others are so big, they fill the entire renal pelvis, these are often termed ‘staghorn calculi’ because of their distinctive shape.

Smaller stones will usually pass naturally whereas larger stones will require intervention. The stones are scored on their size to determine likelihood of success of certain interventions.

The formation of kidney stones cannot be attributed to any specific cause, but several factors can increase the risk. Risk factors include:

  • Dehydration
  • Family history
  • Certain foods – high sodium diet, oxalate and foods that increase acid levels
  • Obesity
  • Diseases / surgery of the digestive tract – e.g. inflammatory bowel disease, gastric bypass surgery
  • Certain medical conditions – hyperparathyroidism, sarcoidosis, UTI & some cancers


Kidney stones
Kidney stones image

Many renal system symptoms are similar so differential diagnosis will be required. The severity of the symptoms for kidney stones will depend on the size & location of the stones; they are often most painful if the stone has migrated into the ureter. Other symptoms include:


  • Intermittent and severe renal pain which radiates to the groin & testis in males
  • Pain worsens during movement
  • Blood in urine
  • Pus in urine
  • Fever
  • Difficulty urinating, feeling of urgency, frequent, painful, burning sensation
  • Urine retention
  • Nausea, vomiting, chills, and fever are seen in case of infection

Kidney Cancer

Each year over 12500 people in the UK are diagnosed with kidney cancer. Kidney cancer usually only affects one kidney. It is very uncommon for cancer to be in both kidneys.


There are different types of kidney cancer. About 8 out of 10 (80%) kidney cancers are renal cell cancers (RCC). They start in the cortex of the kidney. Kidney cancer can also start in the ureter and renal pelvis but this is rare.


There are different types of RCC. The most common type is clear cell renal cancer. Less common types are:

  • Papillary renal cell cancer
  • Chromophobe renal cell cancer

Kidney cancer that starts in the renal pelvis is usually a type of cancer called urothelial cancer or transitional cell carcinoma (TCC).

Another rare type of kidney cancer is called collecting duct cancer (CDC). This cancer has features of both RCC and of urothelial cancer.

Sometimes kidney cancer can spread to lymph nodes close to the kidney. Lymph nodes are part of the lymphatic system. The lymphatic system helps protect us from infection and disease. It is more difficult to treat cancer which has spread (remember the TMN scoring system).

The exact cause of kidney cancer is unknown but there are several risk factors:

  • Obesity
  • Old age: kidney cancer risk increases with age
  • Smoking
  • Hypertension
  • Some disease conditions e.g. Birt-Hogg-Dube syndrome
  • Long-term treatment of kidney disease using dialysis increases risk

Symptoms of progressed kidney cancer may include:

  • Blood in urine
  • Sudden weight loss
  • Lump in the abdomen
  • Pain in the lower back
  • Fever
  • Loss of appetite

Transitional Cell Carcinoma can (TCC) be problematic as it can cause obstructions resulting in other conditions such as hydronephrosis. A tumour in the ureter may require surgery or a catheter to act as a stent to allow passage of urine.

Further reading – read more about Kidney Cancer and other diseases of the renal system on

Bladder Cancer

Although it is rare, TCC can also start in the bladder. Advanced bladder cancer may require surgical removal of the bladder. It would require a special intervention in this case called an ileal conduit which will be discussed further in the treatment’s module.