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.

About a third of untreated patients have spontaneous remission, another third progress to require dialysis and the last third continue to have proteinuria, without progression of renal failure.

The remainder is secondary due to:

- autoimmune conditions (e.g., systemic lupus erythematosus)

- infections (e.g., syphilis, malaria, hepatitis B, hepatitis C)

- drugs (e.g., captopril, NSAIDs, penicillamine, probenecid).

- inorganic salts (e.g. gold, mercury).

- tumors, frequently solid tumors of the lung and colon; hematological malignancies such as chronic lymphocytic leukemia are less common.

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.

The cause of lupus nephritis, a genetic predisposition, plays role in lupus nephritis. Multiple genes, many of which are not yet identified, mediate this genetic predisposition.

The immune system protects the human body from infection, with immune system problems it cannot distinguish between harmful and healthy substances. Lupus nephritis affects approximately 3 out of 10,000 people.

Nephritis represents the ninth most common cause of death among all women in the US (and the fifth leading cause among non-Hispanic black women).

Worldwide the highest rates of nephritis are 50-55% for African or Asian descent, then Hispanic at 43% and Caucasian at 17%.

Nephrotic syndrome can affect any age, although it is mainly found in adults with a ratio of adults to children of 26 to 1.

The syndrome presents in different ways in the two groups: the most frequent glomerulopathy in children is minimal change disease (66% of cases), followed by focal segmental glomerulosclerosis (8%) and mesangiocapillary glomerulonephritis (6%). In adults the most common disease is mesangiocapillary glomerulonephritis (30-40%), followed by focal and segmental glomeruloesclerosis (15-25%) and minimal change disease (20%). The latter usually presents as secondary and not primary as occurs in children. Its main cause is diabetic nephropathy. It usually presents in a patient’s 40s or 50s.

Of the glomerulonephritis cases approximately 60% to 80% are primary, while the remainder are secondary.

There are also differences in epidemiology between the sexes, the disease is more common in men than in women by a ratio of 2 to 1.

The epidemiological data also reveals information regarding the most common way that symptoms develop in patients with nephrotic syndrome: spontaneous remission occurs in up to 20% or 30% of cases during the first year of the illness. However, this improvement is not definitive as some 50% to 60% of patients die and / or develop chronic renal failure 6 to 14 years after this remission. On the other hand, between 10% and 20% of patients have continuous episodes of remissions and relapses without dying or jeopardizing their kidney. The main causes of death are cardiovascular, as a result of the chronicity of the syndrome, and thromboembolic accidents.

The prognosis for nephrotic syndrome under treatment is generally good although this depends on the underlying cause, the age of the patient and their response to treatment. It is usually good in children, because minimal change disease responds very well to steroids and does not cause chronic renal failure. Any relapses that occur become less frequent over time; the opposite occurs with mesangiocapillary glomerulonephritis, in which the kidney fails within three years of the disease developing, making dialysis necessary and subsequent kidney transplant. In addition children under the age of 5 generally have a poorer prognosis than prepubescents, as do adults older than 30 years of age as they have a greater risk of kidney failure.

Other causes such as focal segmental glomerulosclerosis frequently lead to end stage renal disease. Factors associated with a poorer prognosis in these cases include level of proteinuria, blood pressure control and kidney function (GFR).

Without treatment nephrotic syndrome has a very bad prognosis especially "rapidly progressing glomerulonephritis", which leads to acute kidney failure after a few months.

Glomerulonephritis (GN), also known as glomerular nephritis, is a term used to refer to several kidney diseases (usually affecting both kidneys). Many of the diseases are characterised by inflammation either of the glomeruli or of the small blood vessels in the kidneys, hence the name, but not all diseases necessarily have an inflammatory component.

As it is not strictly a single disease, its presentation depends on the specific disease entity: it may present with isolated hematuria and/or proteinuria (blood or protein in the urine); or as a nephrotic syndrome, a nephritic syndrome, acute kidney injury, or chronic kidney disease.

They are categorized into several different pathological patterns, which are broadly grouped into non-proliferative or proliferative types. Diagnosing the pattern of GN is important because the outcome and treatment differs in different types. Primary causes are intrinsic to the kidney. Secondary causes are associated with certain infections (bacterial, viral or parasitic pathogens), drugs, systemic disorders (SLE, vasculitis), or diabetes.

Glomerulonephritis refers to an inflammation of the glomerulus, which is the unit involved in filtration in the kidney. This inflammation typically results in one or both of the nephrotic or nephritic syndromes.

Treatment/management of nephritis depends on what has provoked the inflammation of the kidney(s). In the case of lupus nephritis, hydroxychloroquine could be used.

The pathophysiology of lupus nephritis has autoimmunity contributing significantly. Autoantibodies direct themselves against nuclear elements. The characteristics of nephritogenic autoantibodies ( lupus nephritis) are: antigen specificity directed at nucleosome, high affinity autoantibodies form intravascular immune complexes, autoantibodies of certain isotypes activate complement.

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

The kidneys are the only body system that are directly affected by tubulointerstitial nephritis. Kidney function is usually reduced; the kidneys can be just slightly dysfunctional, or fail completely.

In chronic tubulointerstitial nephritis, the most serious long-term effect is kidney failure. When the proximal tubule is injured, sodium, potassium, bicarbonate, uric acid, and phosphate reabsorption may be reduced or changed, resulting in low bicarbonate, known as metabolic acidosis, low potassium, low uric acid known as hypouricemia, and low phosphate known as hypophosphatemia. Damage to the distal tubule may cause loss of urine-concentrating ability and polyuria.

In most cases of acute tubulointerstitial nephritis, the function of the kidneys will return after the harmful drug is not taken anymore, or when the underlying disease is cured by treatment. If the illness is caused by an allergic reaction, a corticosteroid may speed the recovery kidney function; however, this is often not the case.

Chronic tubulointerstitial nephritis has no cure. Some patients may require dialysis. Eventually, a kidney transplant may be needed.

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

Complications of analgesic nephropathy include pyelonephritis and end-stage kidney disease. Risk factors for poor prognosis include recurrent urinary tract infection and persistently elevated blood pressure. Analgesic nephropathy also appears to increase the risk of developing cancers of the urinary system.

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

Common causes include infection, or reaction to medication such as an analgesic or antibiotics such as methicillin (meticillin). Reaction to medications causes 71% to 92% of cases.

This disease is also caused by other diseases and toxins that damage the kidney. Both acute and chronic tubulointerstitial nephritis can be caused by a bacterial infection in the kidneys known as pyelonephritis, but the most common cause is by an adverse reaction to a drug. The drugs that are known to cause this sort of reaction are antibiotics such as penicillin

and cephalexin, and nonsteroidal anti-inflammatory drugs (aspirin less frequently than others), as well as proton-pump inhibitors, rifampicin, sulfa drugs, fluoroquinolones, diuretics, allopurinol, and phenytoin. The time between exposure to the drug and the development of acute tubulointerstitial nephritis can be anywhere from 5 days to 5 months (fenoprofen induced).

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.

The term "analgesic nephropathy" usually refers to damage induced by excessive use of combinations of these medications, specifically combinations that include phenacetin. For this reason, it is also called analgesic abuse nephropathy. Murray prefers the less judgmental analgesic-associated nephropathy. Both terms are abbreviated to the acronym AAN, by which the condition is also commonly known.

Patients with ESKD are at increased overall risk for cancer. This risk is particularly high in younger patients and gradually diminishes with age. Medical specialty professional organizations recommend that physicians do not perform routine cancer screening in patients with limited life expectancies due to ESKD because evidence does not show that such tests lead to improved patient outcomes.

Mesangial proliferative glomerulonephritis is a form of glomerulonephritis associated primarily with the mesangium. There is some evidence that interleukin-10 may inhibit it in an animal model. It is classified as type II lupus nephritis by the World Health Organization (WHO).

Diffuse proliferative nephritis (DPN) or glomerulonephritis (DPGN) is a type of glomerulonephritis that is the most serious form of renal lesions in SLE and is also the most common, occurring in 35% to 60% of patients. Most of the glomeruli show endothelial and mesangial proliferation affecting the entire glomerulus, leading to diffuse hypercellularity of the glomeruli, producing in some cases epithelial crescents that fill Bowman's space. When extensive, immune complexes create an overall thickening of the capillary wall, resembling rigid "wire loops" on routine light microscopy. Electron microscopy reveals electron-dense subendothelial immune complexes (between endothelium and basement membrane). Immune complexes can be visualized by staining with fluorescent antibodies directed against immunoglobulins or complement, resulting in a granular fluorescent staining pattern. In due course, glomerular injury gives rise to scarring (glomerulosclerosis). Most of these patients have hematuria with moderate to severe proteinuria, hypertension, and renal insufficiency.

In one review, over half of individuals with shunt nephritis made a complete recovery. An additional 40% of individuals had persistent urine abnormalities or end-stage renal disease. Death occurred in 9%.

Mesangial cells in the renal glomerulus use endocytosis to take up and degrade circulating immunoglobulin. This normal process stimulates mesangial cell proliferation and matrix deposition. Therefore, during times of elevated circulating immunoglobulin ("i.e." lupus and IgA nephropathy) one would expect to see an increased number of mesangial cells and matrix in the glomerulus. This is characteristic of nephritic syndromes.