<s>[INST] What are the first signs of kidney disease? [/INST] Clinicians usually find out about kidney diseases during blood or urine tests. It is hard to detect the early stages of chronic kidney disease due to homeostasis. However, patients with acute or later stages of renal diseases may experience:

Blood in urine: a sign of disrupted filtering functions of the kidneys. Healthy kidneys have filters called glomeruli which keep red blood cells in the blood vessels rather than entering the urinary tract. Blood in the urine may be an early sign of glomerulonephritis. 
Foamy urine: may be an indication of chronic kidney diseases due to tubular or glomerular dysfunctions. Proteins are large particles that cannot cross the glomerular filtration barriers. Relatively smaller albumin particles may pass the barrier, but tubular reabsorption would take the molecules back into the blood. When the functions are disrupted, protein enters the kidneys and would not removed from the urine during reabsorption. A high concentration of protein in the urine is termed nephrotic syndrome.
Polyuria (urinating more than usual): indicates that water molecules are not efficiently reabsorbed into the blood vessels. The urine concentration is low, and the patients urinate more frequently, especially at night. 
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Other clinical features, including anemia, nausea, lowered immunity against infections, and infertility, may also occur later in chronic kidney disease. Source: KLARITY HEALTH LIBRARY. Link: https://my.klarity.health/kidney-disease-faq/. Field: Nephrology. Disease: Kidney Disease </s>