<s>[INST] What are the most common kidney diseases? [/INST] The three main categories of kidney diseases are nephritis, acute renal failure (ARF), and chronic kidney disease (CKD). Nephritis can lead to both acute and chronic renal diseases.

Kidney infections and inflammation define nephritis. The type of nephritis depends on the region of the inflammation. For instance, glomerulonephritis indicates damage in glomeruli (the “ball” shaped filters in the kidney); bacterial infections in the urinary tract cause pyelonephritis; and interstitial nephritis occurs between the tubules in the kidneys, mostly caused by allergic reactions to drugs. Nephritis can either be acute or chronic, depending on the length and frequency of inflammation. 

Acute renal failure is defined by a sudden glomerular filtration rate (GFR) drop and a persistent increase in urea and creatinine concentration. The condition develops rapidly and can be fatal. The causes can be categorised into pre-renal, intrinsic renal, and post-renal causes, of which vascular diseases, nephritis, and tubular injuries are the most common triggers.

Other than being caused by recurrent/long-term renal damage, chronic kidney disease can also be triggered by other chronic conditions, such as diabetes, high blood pressure, and high-fat levels. There are five stages of the disease, and the condition can rarely be diagnosed during early stages, as most patients are asymptomatic until the GFR falls below 15 ml/min (whilst normal GFR is over 90 ml/min). However, patients can prevent the condition by adopting healthy living habits and controlling other age-related diseases due to their slow development. Source: KLARITY HEALTH LIBRARY. Link: https://my.klarity.health/kidney-disease-faq/. Field: Nephrology. Disease: Kidney Disease </s>