According to the United States Renal Data System (USRDS), hypertensive nephropathy accounts for more than one-third of patients on hemodialysis and the annual mortality rate for patients on hemodialysis is 23.3%.

Haemodialysis is recommended for patients who progress to end-stage kidney disease (ESKD) and hypertensive nephropathy is the second most common cause of ESKD after diabetes.

Patient prognosis is dependent on numerous factors including age, ethnicity, blood pressure and glomerular filtration rate. Changes in lifestyle factors, such as reduced salt intake and increased physical activity have been shown to improve outcomes but are insufficient without pharmacological treatment.

The long-term use of lithium, a medication commonly used to treat bipolar disorder and schizoaffective disorders, is known to cause nephropathy.

Despite expensive treatments, lupus nephritis remains a major cause of morbidity and mortality in people with relapsing or refractory lupus nephritis.

In the general population, the frequency of medullary sponge kidney disease is reported to be 0.02–0.005%; that is, 1 in 5000 to 1 in 20,000. The frequency of medullary sponge kidney has been reported by various authors to be 1221% in patients with kidney stones. The disease is bilateral in 70% of cases.

The incidence of hypertensive nephropathy varies around the world. For instance, it accounts for as many as 25% and 17% of patients starting dialysis for end-stage kidney disease in Italy and France respectively. Contrastingly, Japan and China report only 6 and 7% respectively. Since the year 2000, nephropathy caused by hypertension has increased in incidence by 8.7% In reality, these figures may be even higher, as hypertension is not always reported as the specific cause of kidney disease.

It has been recognized that the incidence of hypertensive nephropathy varies with ethnicity. Compared to Caucasians, African Americans in the USA are much more likely to develop hypertensive nephropathy. Of those who do, the proportion who then go on to develop end-stage renal failure is 3.5 times higher than in the Caucasian population. In addition to this, African Americans tend to develop hypertensive nephropathy at a younger age than Caucasians (45 to 65, compared to >65).

Complications associated with medullary sponge kidney include the following:

- Kidney stones

- Urinary tract infection (UTI)

- Blood in the urine

- Distal renal tubular acidosis (Type 1 RTA)

- Chronic kidney disease (rarely)

- Marked chronic pain

The greatest risk factors for RCC are lifestyle-related; smoking, obesity and hypertension (high blood pressure) have been estimated to account for up to 50% of cases.

Occupational exposure to some chemicals such as asbestos, cadmium, lead, chlorinated solvents, petrochemicals and PAH (polycyclic aromatic hydrocarbon) has been examined by multiple studies with inconclusive results.

Another suspected risk factor is the long term use of non-steroidal anti-inflammatory drugs (NSAIDS).

Finally, studies have found that women who have had a hysterectomy are at more than double the risk of developing RCC than those who have not. Moderate alcohol consumption, on the other hand, has been shown to have a protective effect. The reason for this remains unclear.

Small angiomyolipomas and those without dilated blood vessels (aneurysms) cause few problems, but angiomyolipomas have been known to grow as rapidly as 4 cm in one year. An angiomyolipoma larger than 5 cm and those containing an aneurysm pose a significant risk of rupture, which is a medical emergency as it is potentially life-threatening. One population study found the cumulative risk of haemorrhage to be 10% in males and 20% in females.

A second problem occurs when the renal angiomyolipomas take over so much kidney that the function is impaired leading to chronic kidney disease. This may be severe enough to require dialysis. A population survey of patients with TSC and normal intelligence found 1% were on dialysis.

Hereditary factors have a minor impact on individual susceptibility with immediate relatives of people with RCC having a two to fourfold increased risk of developing the condition. Other genetically linked conditions also increase the risk of RCC, including hereditary papillary renal carcinoma, hereditary leiomyomatosis, Birt–Hogg–Dube syndrome, hyperparathyroidism-jaw tumor syndrome, familial papillary thyroid carcinoma, von Hippel–Lindau disease and sickle cell disease.

The most significant disease affecting risk however is not genetically linked – patients with acquired cystic disease of the kidney requiring dialysis are 30 times more likely than the general population to develop RCC.

Benign nephrosclerosis alone hardly ever causes severe damage to the kidney, except in susceptible populations, such as African Americans, where it may lead to uremia and death. However, all persons with this disease usually show some functional impairment, such as loss of concentration or a variably diminished GFR. A mild degree of proteinuria is a frequent finding.

Male gender, proteinuria (especially > 2 g/day), hypertension, smoking, hyperlipidemia, older age, familial disease and elevated creatinine concentrations are markers of a poor outcome. Frank hematuria has shown discordant results with most studies showing a better prognosis, perhaps related to the early diagnosis, except for one group which reported a poorer prognosis. Proteinuria and hypertension are the most powerful prognostic factors in this group.

There are certain other features on kidney biopsy such as interstitial scarring which are associated with a poor prognosis. ACE gene polymorphism has been recently shown to have an impact with the DD genotype associated more commonly with progression to kidney failure.

Angiomyolipomas are the most common benign tumour of the kidney and are found either in patients with tuberous sclerosis or sporadically. About 80–90% of cases are sporadic and these are most commonly found in middle-aged women.

In patients with TSC, a longitudinal study found 80% will have some form of renal lesion by around 10 years of age. Of these, 75% are angiomyolipomas and 17% cysts. The angiomyolipomas increased in size in around 60% of these children. An autopsy study and TSC clinic survey found a prevalence of 67% and 85% respectively for patients with TSC. Both genders are affected equally.

Up to 27 percent of individuals greater than 50 years of age may have simple renal cysts that cause no symptoms.

Renal failure is defined by functional impairment of the kidney. Renal failure can be acute or chronic, and can be further broken down into categories of pre-renal, intrinsic renal and post-renal.

Pre-renal failure refers to impairment of supply of blood to the functional nephrons including renal artery stenosis. Intrinsic renal diseases are the classic diseases of the kidney including drug toxicity and nephritis. Post-renal failure is outlet obstruction after the kidney, such as a kidney stone or prostatic bladder outlet obstruction.

Renal failure may require medication, dietary and lifestyle modification and dialysis.

Primary renal cell carcinomas as well as metastatic cancers can affect the kidney.

Benign nephrosclerosis refers to the renal changes most commonly occurring in association with long-standing hypertension. It is termed benign because it rarely progresses to clinically significant renal insufficiency or renal failure.

The causes of diseases of the body are common to the urinary tract. Structural and or traumatic change can lead to hemorrhage, functional blockage or inflammation. Colonisation by bacteria, protozoa or fungi can cause infection. Uncontrolled cell growth can cause neoplasia.

For example:

- Urinary tract infections (UTIs), interstitial cystitis

- incontinence (involuntary loss of urine), benign prostatic hyperplasia (where the prostate overgrows), prostatitis (inflammation of the prostate).

- Urinary retention, which is a common complication of benign prostatic hyperplasia (BPH), though it can also be caused by other types of urinary tract obstruction, nerve dysfunction, tethered spinal cord syndrome, constipation, infection and certain medications.

- Transitional cell carcinoma (bladder cancer), renal cell carcinoma (kidney cancer), and prostate cancer are examples of neoplasms affecting the urinary system.

- Urinary tract obstruction

The term "uropathy" refers to a disease of the urinary tract, while "nephropathy" refers to a disease of the kidney.

There are three main mechanisms to cause proteinuria:

- Due to disease in the glomerulus

- Because of increased quantity of proteins in serum (overflow proteinuria)

- Due to low reabsorption at proximal tubule (Fanconi syndrome)

Proteinuria can also be caused by certain biological agents, such as bevacizumab (Avastin) used in cancer treatment. Excessive fluid intake (drinking in excess of 4 litres of water per day) is another cause.

Also leptin administration to normotensive Sprague Dawley rats during pregnancy significantly increases urinary protein excretion.

Proteinuria may be a sign of renal (kidney) damage. Since serum proteins are readily reabsorbed from urine, the presence of excess protein indicates either an insufficiency of absorption or impaired filtration. People with diabetes may have damaged nephrons and develop proteinuria. The most common cause of proteinuria is diabetes, and in any person with proteinuria and diabetes, the cause of the underlying proteinuria should be separated into two categories: diabetic proteinuria versus the field.

With severe proteinuria, general hypoproteinemia can develop which results in

diminished oncotic pressure. Symptoms of diminished oncotic pressure may include ascites, edema and hydrothorax.

Prognosis of individuals with renovascular hypertension is not easy to determine. Those with atherosclerotic renal artery disease have a high risk of mortality, furthermore those who also have renal dysfunction have a higher mortality risk.

However, the majority of renovascular diseases can be improved with surgery.

Proteinuria may be a feature of the following conditions:

- Nephrotic syndromes (i.e. intrinsic renal failure)

- Pre-eclampsia

- Eclampsia

- Toxic lesions of kidneys

- Amyloidosis

- Collagen vascular diseases (e.g. systemic lupus erythematosus)

- Dehydration

- Glomerular diseases, such as membranous glomerulonephritis, focal segmental glomerulonephritis, minimal change disease (lipoid nephrosis)

- Strenuous exercise

- Stress

- Benign orthostatic (postural) proteinuria

- Focal segmental glomerulosclerosis (FSGS)

- IgA nephropathy (i.e. Berger's disease)

- IgM nephropathy

- Membranoproliferative glomerulonephritis

- Membranous nephropathy

- Minimal change disease

- Sarcoidosis

- Alport's syndrome

- Diabetes mellitus (diabetic nephropathy)

- Drugs (e.g. NSAIDs, nicotine, penicillamine, lithium carbonate, gold and other heavy metals, ACE inhibitors, antibiotics, or opiates (especially heroin)

- Fabry's disease

- Infections (e.g. HIV, syphilis, hepatitis, poststreptococcal infection, urinary schistosomiasis)

- Aminoaciduria

- Fanconi syndrome in association with Wilson disease

- Hypertensive nephrosclerosis

- Interstitial nephritis

- Sickle cell disease

- Hemoglobinuria

- Multiple myeloma

- Myoglobinuria

- Organ rejection:

- Ebola virus disease

- Nail patella syndrome

- Familial Mediterranean fever

- HELLP Syndrome

- Systemic lupus erythematosus

- Granulomatosis with polyangiitis

- Rheumatoid arthritis

- Glycogen storage disease type 1

- Goodpasture's syndrome

- Henoch–Schönlein purpura

- A urinary tract infection which has spread to the kidney(s)

- Sjögren's syndrome

- Post-infectious glomerulonephritis

In one study, hypouricemia was found in 4.8% of hospitalized women and 6.5% of hospitalized men. (The definition was less than 0.14 mmol l-1 for women and less than 0.20 mmol l-1 in men.)

Kidney tumours may be discovered on medical imaging incidentally (i.e. an incidentaloma), or may be present in patients as an abdominal mass or kidney cyst, hematuria, abdominal pain, or manifest first in a paraneoplastic syndrome that seems unrelated to the kidney.

A renal cyst or kidney cyst, is a fluid collection in or on the kidney. There are several types based on the "Bosniak classification". The majority are benign, simple cysts that can be monitored and not intervened upon. However, some are cancerous or are suspicious for cancer and are commonly removed in a surgical procedure called nephrectomy.

Numerous renal cysts are seen in the cystic kidney diseases, which include polycystic kidney disease and medullary sponge kidney.

The cause of renovascular hypertension is consistent with any narrowing/blockage of blood supply to the renal organ (renal artery stenosis). As a consequence of this action the renal organs release hormones that indicate to the body to maintain a higher amount of sodium and water, which in turn causes blood pressure to rise. Factors that may contribute are: diabetes, high cholesterol and advanced age, also of importance is that a unilateral

condition is sufficient to cause renovascular hypertension.

Men are affected three times as often as women. There is also marked geographic variation in the prevalence of IgA nephropathy throughout the world. It is the most common glomerular disease in the Far East and Southeast Asia, accounting for almost half of all the patients with glomerular disease. However, it accounts for only about 25% of the proportion in European and about 10% among North Americans, with African–Americans having a very low prevalence of about 2%. However, a confounding factor in this analysis is the existing policy of screening and use of kidney biopsy as an investigative tool. School children in Japan undergo routine urinalysis (as do army recruits in Singapore) and any suspicious abnormality is pursued with a kidney biopsy, which might partly explain the high observed incidence of IgA nephropathy in those countries.

Hypertension is one of the most common complex disorders. The etiology of hypertension differs widely amongst individuals within a large population. And by definition, essential hypertension has no identifiable cause. However, several risk factors have been identified.